/* Calculus Workbook

   Two panes and nothing else: your textbook on one side, one long sheet of

   paper on the other. All the chrome floats, so every pixel of height and

   width goes to the work. */



:root {

  --paper:      #faf8f4;

  --paper-2:    #f3f0e9;

  --paper-3:    #ebe7dd;

  --sheet:      #ffffff;

  --ink:        #17150f;

  --ink-2:      #5d574b;

  --ink-3:      #948c7c;

  --line:       #e6e1d5;

  --line-2:     #cec7b6;



  --todo:  #c98a10;

  --doing: #3358c4;

  --done:  #2c8250;

  --stuck: #b83a3a;



  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Constantia, Georgia, serif;

  --sans:  "Segoe UI", -apple-system, BlinkMacSystemFont, "Helvetica Neue", sans-serif;

  --mono:  "Cascadia Mono", "SF Mono", Consolas, "Liberation Mono", monospace;



  --r:   6px;

  --r-s: 4px;

  --shadow-1: 0 1px 2px rgba(23, 21, 15, .06);

  --shadow-2: 0 10px 30px -14px rgba(23, 21, 15, .45);

  --shadow-3: 0 30px 70px -24px rgba(23, 21, 15, .5);

  --ring: 0 0 0 3px rgba(23, 21, 15, .13);



  --split: 52%;

  --dock: 30vh;

  --book-zoom: 1;

  --rail: 46px;

}



* { box-sizing: border-box; min-width: 0; }

[hidden] { display: none !important; }

html, body { height: 100%; margin: 0; }

body {

  background: var(--paper);

  color: var(--ink);

  font: 400 13.5px/1.55 var(--sans);

  overflow: hidden;

  -webkit-font-smoothing: antialiased;

}

::selection { background: #f0e3bd; }

:focus-visible { outline: none; box-shadow: var(--ring); border-radius: var(--r-s); }



/* ============================================================== atoms */

.btn {

  display: inline-flex; align-items: center; justify-content: center; gap: 6px;

  height: 30px; padding: 0 12px;

  font: 500 12.5px/1 var(--sans); color: var(--ink); white-space: nowrap;

  background: linear-gradient(180deg, #fff, var(--paper-2));

  border: 1px solid var(--line-2); border-radius: var(--r);

  box-shadow: var(--shadow-1); cursor: pointer;

  transition: background .13s, border-color .13s, transform .06s, box-shadow .13s;

}

.btn:hover { border-color: var(--ink-3); background: #fff; }

.btn:active { transform: translateY(1px); box-shadow: none; }

.btn.primary { color: var(--paper); background: var(--ink); border-color: var(--ink); }

.btn.primary:hover { background: #2c2820; }

.btn.primary:disabled { opacity: .38; cursor: not-allowed; transform: none; }

.btn.ghost { background: transparent; border-color: transparent; box-shadow: none; color: var(--ink-2); }

.btn.ghost:hover { background: var(--paper-3); color: var(--ink); }

.btn.danger { color: var(--stuck); }

.btn.danger:hover { background: #fbecec; }



.input, .select, .code {

  height: 30px; padding: 0 10px; width: 100%;

  font: 400 12.5px/1 var(--sans); color: var(--ink);

  background: #fff; border: 1px solid var(--line-2); border-radius: var(--r);

  box-shadow: inset 0 1px 2px rgba(23,21,15,.04);

  transition: border-color .13s, box-shadow .13s;

}

.input:hover, .select:hover { border-color: var(--ink-3); }

.input:focus, .select:focus, .code:focus { outline: none; border-color: var(--ink); box-shadow: var(--ring); }

.input:disabled { background: var(--paper-2); color: var(--ink-3); }

.input::placeholder { color: var(--ink-3); }

.select {

  appearance: none; padding-right: 28px; cursor: pointer;

  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='7'%3E%3Cpath d='M1 1l4 4 4-4' fill='none' stroke='%235d574b' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E");

  background-repeat: no-repeat; background-position: right 10px center;

}

.code { height: auto; min-height: 96px; padding: 9px 10px; resize: vertical; font: 400 11.5px/1.6 var(--mono); }

.code.tall { min-height: 260px; }



.filebtn { display: inline-block; position: relative; }

.filebtn input { position: absolute; inset: 0; opacity: 0; cursor: pointer; }

.filebtn span {

  display: inline-flex; align-items: center; height: 32px; padding: 0 14px;

  font: 500 12.5px/1 var(--sans);

  border: 1px dashed var(--line-2); border-radius: var(--r);

  background: #fff; color: var(--ink-2);

}

.filebtn:hover span { border-color: var(--ink); color: var(--ink); }

.filebtn.small span { height: 28px; font-size: 12px; }



.seg-ctl { display: inline-flex; padding: 2px; gap: 2px; background: var(--paper-3); border-radius: var(--r); }

.seg-ctl button {

  height: 22px; padding: 0 9px; border: 0; border-radius: 3px;

  font: 500 11.5px/1 var(--sans); color: var(--ink-2);

  background: transparent; cursor: pointer; transition: background .13s, color .13s;

}

.seg-ctl button:hover { color: var(--ink); }

.seg-ctl button.on { background: #fff; color: var(--ink); box-shadow: var(--shadow-1); }



.tag { display: inline-flex; align-items: center; height: 22px; padding: 0 8px;

  font: 500 11px/1 var(--sans); color: var(--ink-2); background: var(--paper-3); border-radius: 99px; }

.dot { display: inline-block; width: 7px; height: 7px; border-radius: 50%; }

.dot.is-todo { background: var(--todo); } .dot.is-doing { background: var(--doing); }

.dot.is-done { background: var(--done); } .dot.is-stuck { background: var(--stuck); }



.track { display: flex; height: 3px; border-radius: 2px; background: var(--line); overflow: hidden; }

.track.big { height: 4px; }

.track .seg { height: 100%; transition: width .25s ease; }

.seg.is-todo { background: var(--todo); } .seg.is-doing { background: var(--doing); }

.seg.is-done { background: var(--done); } .seg.is-stuck { background: var(--stuck); }



.warn { color: var(--stuck); }

.ok { color: var(--done); }

.note { color: var(--ink-2); font-size: 12.5px; margin: 0 0 12px; max-width: 62ch; }

.msg { min-height: 18px; font-size: 12px; color: var(--ink-2); margin: 8px 0 0; }

.grow { flex: 1; }



/* =============================================================== gate */

#gate {

  position: fixed; inset: 0; overflow-y: auto; padding: 40px 20px; z-index: 40;

  background:

    radial-gradient(1100px 600px at 15% -10%, #fff 0%, transparent 60%),

    repeating-linear-gradient(0deg, transparent 0 27px, rgba(23,21,15,.035) 27px 28px),

    var(--paper);

}

.gate-card {

  max-width: 640px; margin: 0 auto; background: var(--sheet);

  border: 1px solid var(--line); border-radius: 12px; box-shadow: var(--shadow-3); overflow: hidden;

}

.gate-card > header { padding: 36px 40px 26px; border-bottom: 1px solid var(--line); }

.mark { width: 42px; height: 42px; display: grid; place-items: center; margin-bottom: 16px;

  font: 400 26px/1 var(--serif); color: var(--paper); background: var(--ink); border-radius: 10px; }

.gate-card h1 { margin: 0; font: 400 30px/1.1 var(--serif); letter-spacing: -.01em; }

.lede { margin: 10px 0 0; color: var(--ink-2); font-size: 14px; max-width: 46ch; }

.steps { list-style: none; margin: 0; padding: 8px 40px 4px; }

.steps li { padding: 20px 0; border-bottom: 1px solid var(--line); }

.steps li:last-child { border-bottom: 0; }

.steps h2 { display: flex; align-items: center; gap: 10px; margin: 0 0 6px; font: 500 14px/1.3 var(--sans); }

.step-n { display: grid; place-items: center; width: 20px; height: 20px; flex: none;

  font: 500 11px/1 var(--mono); color: var(--ink-2); background: var(--paper-3); border-radius: 50%; }

.steps p { margin: 0 0 12px 30px; color: var(--ink-2); font-size: 12.8px; max-width: 54ch; }

.steps .select, .steps .filebtn { margin-left: 30px; }

.steps .select { max-width: 380px; }

.filestate { margin: 10px 0 0 30px !important; font-size: 12px; }

.gate-card > footer { padding: 20px 40px 28px; }

.gate-card > footer .btn { height: 38px; padding: 0 20px; font-size: 13.5px; }



/* ========================================================== workspace */

#workspace { display: flex; height: 100%; position: relative; }

.pane { display: flex; flex-direction: column; min-width: 0; position: relative; }

.pane[data-slot="left"], .pane-book { order: 1; flex: 0 0 var(--split); display: flex; }

.pane[data-slot="right"], .pane-sheet { order: 3; flex: 1 1 0; display: flex; }

.pane-book { background: var(--paper-2); }

.pane-sheet { background: var(--paper); }



.splitter { flex: 0 0 7px; order: 2; cursor: col-resize; background: var(--paper-3);

  border-left: 1px solid var(--line); border-right: 1px solid var(--line); position: relative; }

.splitter::after {

  content: ""; position: absolute; top: 50%; left: 50%; width: 3px; height: 34px;

  transform: translate(-50%, -50%); border-radius: 2px; background: var(--line-2);

}

.splitter:hover::after, .splitter.dragging::after { background: var(--ink-3); }

.splitter.dragging { background: var(--line); }



/* ---------------------------------------------------------------- HUD */

.hud {

  position: absolute; left: 12px; bottom: 12px; z-index: 62;

  display: flex; align-items: center; gap: 6px; padding: 4px 6px 4px 10px;

  background: rgba(250, 248, 244, .96); backdrop-filter: blur(10px) saturate(1.2);

  border: 1px solid var(--line-2); border-radius: 99px; box-shadow: var(--shadow-2);

  opacity: .9; transition: opacity .16s;

}

.hud:hover, .hud:focus-within { opacity: 1; }

.hud:focus-within { border-color: var(--ink-3); }

.hud-progress { display: flex; align-items: center; gap: 7px; }

.hud-progress .track { width: 84px; }

.hud-progress span { font: 500 11px/1 var(--mono); color: var(--ink-2); }

.hud-sep { width: 1px; height: 18px; background: var(--line-2); margin: 0 2px; }

.icon {

  width: 26px; height: 26px; display: grid; place-items: center;

  font-size: 13px; color: var(--ink-2); background: transparent;

  border: 0; border-radius: 50%; cursor: pointer; transition: background .12s, color .12s;

}

.icon:hover { background: var(--paper-3); color: var(--ink); }

.savestate { font: 400 10px/1 var(--mono); color: var(--ink-3); padding-right: 6px; min-width: 32px; }



/* --------------------------------------------------------- book pane */

.pages { flex: 1; overflow: auto; padding: 14px 0 40px; overscroll-behavior: contain;

  display: flex; flex-direction: column; align-items: safe center; }

.banner { order: -1; margin: 0; padding: 7px 14px; font-size: 12px; color: #7a5a12;

  background: #fdf4dd; border-bottom: 1px solid #eedfae; }

.sheet { flex: 0 0 auto; width: calc(min(97%, 960px) * var(--book-zoom));

  margin: 0 0 18px; transition: width .12s ease-out; }

.sheet-tab { display: flex; align-items: baseline; gap: 8px; padding: 0 2px 5px; font-size: 11px; color: var(--ink-3); }

.sheet-tab b { flex: none; font: 600 11.5px/1 var(--mono); color: var(--ink); }

.sheet-tab i { font-style: normal; }

.sheet-tab span { color: var(--ink-2); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.sheet-tab em { margin-left: auto; flex: none; font: 400 10.5px/1 var(--mono); font-style: normal; }

.sheet-body { position: relative; background: var(--sheet); border: 1px solid var(--line-2);

  border-radius: 3px; box-shadow: var(--shadow-2); }

.sheet-body canvas { display: block; width: 100%; height: auto; }



.hot-zone { position: absolute; background: transparent; cursor: pointer; }

.hot-zone:hover { background: rgba(23,21,15,.04); border-radius: 3px; }

.hot { position: absolute; padding: 0; border: 0; border-radius: 3px; cursor: pointer; background: transparent; }

.hot::after { content: ""; position: absolute; inset: -2px; border-radius: 3px; background: currentColor; opacity: .34; }

.hot:hover { box-shadow: 0 0 0 2px var(--ink); }

.hot.picked { box-shadow: 0 0 0 2px var(--ink), 0 0 0 6px rgba(23,21,15,.13); }

.hot.ghost { padding: 1px 5px; font: 600 10px/1.3 var(--mono); color: var(--ink); border: 1px dashed currentColor; }

.hot.ghost::after { opacity: .1; }

.hot.is-todo { color: var(--todo); } .hot.is-doing { color: var(--doing); }

.hot.is-done { color: var(--done); } .hot.is-stuck { color: var(--stuck); }



/* ------------------------------------------------------------- paper */

.paper-scroll { flex: 1; overflow-y: auto; background: #f2eee6; padding: 20px 16px 140px; }

.paper { width: 100%; background: transparent; padding: 0; border: none; }

.doc-paper {
  max-width: 860px; margin: 0 auto; background: #ffffff;
  border: 1px solid var(--line-2); border-radius: 6px;
  box-shadow: 0 4px 28px rgba(23, 21, 15, 0.08);
  padding: 36px 44px 80px;
  font-size: calc(14.5px * var(--doc-scale, 1));
}

.sheet-zoomer {
  display: inline-flex; align-items: center; gap: 2px;
  background: var(--paper-3); border-radius: 99px; padding: 2px;
}
.sheet-zoomer button {
  height: 22px; min-width: 26px; padding: 0 4px; border: 0; border-radius: 99px;
  font: 600 11px/1 var(--sans); color: var(--ink); background: #fff;
  cursor: pointer; transition: all .12s;
}
.sheet-zoomer button:hover {
  background: var(--ink); color: #fff;
}

.doc-header {
  margin-bottom: 28px; padding-bottom: 20px; border-bottom: 2px solid var(--ink);
}
.doc-course-title {
  font: 500 11.5px/1 var(--mono); color: var(--ink-3); text-transform: uppercase; letter-spacing: 0.06em;
}
.doc-hw-title {
  margin: 6px 0 10px; font: 400 26px/1.2 var(--serif); color: var(--ink);
}
.doc-meta-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
}
.doc-stat-pill {
  font: 500 11.5px/1 var(--sans); color: var(--ink-2); background: var(--paper-2); padding: 4px 10px; border-radius: 99px;
}
.doc-progress-pill {
  font: 600 11.5px/1 var(--mono); color: var(--done); background: rgba(46, 125, 50, 0.1); padding: 4px 10px; border-radius: 99px;
}

.doc-sec {
  margin-bottom: 34px;
}
.doc-sec-header {
  display: flex; align-items: baseline; justify-content: space-between; gap: 12px;
  margin-bottom: 16px; padding-bottom: 8px; border-bottom: 1.5px solid var(--line-2);
}
.doc-sec-title {
  margin: 0; font: 600 16px/1.3 var(--serif); color: var(--ink);
}
.doc-sec-actions {
  display: flex; align-items: center; gap: 8px; flex: none;
}
.doc-sec-count {
  font: 500 11px/1 var(--mono); color: var(--ink-3);
}

.doc-prob-list {
  display: flex; flex-direction: column; gap: 18px;
}

.doc-prob {
  padding: 18px 22px 18px;
  background: #ffffff;
  border: 1px solid #e7e2d7;
  border-radius: 8px;
  box-shadow: 0 1px 4px rgba(23, 21, 15, 0.03);
  transition: border-color .15s, box-shadow .15s;
}
.doc-prob:hover {
  border-color: #d8d0c2;
  box-shadow: 0 2px 8px rgba(23, 21, 15, 0.05);
}
.doc-prob.current {
  border-color: #d49a18;
  box-shadow: 0 0 0 2px rgba(212, 154, 24, 0.25);
}
.doc-prob.is-done {
  border-left: 3px solid var(--done);
}

.doc-prob-bar {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  margin-bottom: 12px;
}
.doc-prob-left {
  display: flex; align-items: baseline; gap: 8px; flex-wrap: wrap; min-width: 0;
}
.doc-prob-num {
  font: 700 16px/1 var(--serif); color: var(--ink);
}
.doc-prob-title {
  font: 500 13px/1.3 var(--sans); color: var(--ink-2);
}
.doc-prob-badge {
  font: 600 9px/1 var(--sans); text-transform: uppercase; padding: 2px 7px; border-radius: 99px; letter-spacing: 0.04em;
}
.doc-prob-badge.is-extra {
  background: #fdf3df; color: #92540c; border: 1px solid #eecf97;
}
.doc-prob-badge.is-unmentioned {
  background: #f1ede3; color: #8c8270; border: 1px dashed #c8beab;
}

.doc-prob-right {
  display: flex; align-items: center; gap: 5px; flex: none;
}
.doc-book-btn {
  height: 22px; padding: 0 7px; font: 500 11px/1 var(--sans);
  border: 1px solid var(--line-2); border-radius: var(--r-s);
  background: var(--paper-2); color: var(--ink-2); cursor: pointer;
  display: inline-flex; align-items: center; gap: 3px;
  transition: background .12s, color .12s, border-color .12s;
}
.doc-book-btn:hover {
  background: #fff; color: var(--ink); border-color: var(--ink-3);
}
.doc-status-btn {
  display: inline-flex; align-items: center; gap: 4px;
  height: 22px; padding: 0 8px; font: 600 11px/1 var(--sans);
  border: 1px solid var(--line-2); border-radius: var(--r-s);
  background: #fff; color: var(--ink-2); cursor: pointer;
  transition: all .12s ease; user-select: none;
}
.doc-status-btn:hover {
  border-color: var(--ink-3); color: var(--ink);
}
.doc-status-btn.is-done {
  background: #ecfdf5; border-color: #a7f3d0; color: #047857;
}
.doc-status-btn.is-doing {
  background: #f3f4f6; border-color: #e5e7eb; color: #4b5563;
}
.doc-status-btn.is-stuck {
  background: #fffbeb; border-color: #fde68a; color: #b45309;
}
.doc-status-btn.is-todo {
  background: #fafaf9; border-color: var(--line-2); color: var(--ink-3);
}
.doc-status-btn .status-glyph {
  font-weight: 700; font-size: 11px;
}
.doc-status-btn .status-label {
  font-weight: 500; font-size: 10.5px;
}

.doc-prob-stmt {
  margin-bottom: 14px; padding: 10px 14px;
  background: #fbf9f4; border-left: 3px solid #dcd4c3;
  border-radius: 0 var(--r-s) var(--r-s) 0;
}
.doc-stmt-group {
  margin: 0 0 6px; font: italic 12.5px/1.45 var(--serif); color: #5a5449;
}
.doc-stmt-formula {
  font: 400 14.5px/1.45 var(--serif); color: var(--ink);
}

/* Solution Steps & Beautiful KaTeX Typography */
.doc-solution-view {
  display: flex; flex-direction: column; gap: 8px;
  margin-bottom: 8px; cursor: pointer; border-radius: var(--r-s);
  padding: 4px 6px; transition: background .12s;
}
.doc-solution-view:hover {
  background: rgba(240, 227, 189, 0.15);
}
.doc-steps-list {
  display: flex; flex-direction: column; gap: 10px;
}
.doc-step-row {
  display: flex; flex-direction: column; gap: 4px;
}
.step-desc {
  font: 400 calc(13.5px * var(--doc-scale, 1))/1.55 var(--sans); color: #3c3830;
}
.step-num {
  font-weight: 600; color: #8c8270; margin-right: 4px;
}
.step-math {
  background: #faf8f4; border-left: 2px solid #e2dacd;
  padding: 6px 14px; border-radius: 0 4px 4px 0;
  font-size: calc(15px * var(--doc-scale, 1)); color: var(--ink);
  overflow-x: auto;
}

/* Vector SVG Graphs embedded in solutions */
.doc-svg-container {
  margin: 12px 0; max-width: 480px;
  border: 1px solid #e7e1d5; border-radius: 6px;
  overflow: hidden; background: #faf8f5;
}
.doc-svg-container svg {
  display: block; width: 100%; height: auto;
}

/* Insight Card */
.doc-insight-card {
  background: #fdfbf3; border: 1px solid #f0e3be;
  border-radius: 6px; padding: 9px 13px; margin-top: 6px;
}
.insight-label {
  font: 600 11px/1 var(--sans); text-transform: uppercase; letter-spacing: 0.04em;
  color: #8c6812; margin-bottom: 4px;
}
.insight-body {
  font: 400 13px/1.55 var(--sans); color: #5c4309;
}

.doc-custom-note {
  font: 400 13.5px/1.65 var(--sans); color: var(--ink);
  white-space: pre-wrap; word-break: break-word;
}
.doc-empty-hint {
  font: italic 12.5px/1.5 var(--sans); color: var(--ink-3); padding: 4px 0;
}

/* Fluid edit area: expands naturally, no internal scroll */
.doc-edit-drawer {
  margin-top: 10px;
}
.doc-raw-editor {
  width: 100%; min-height: 80px; height: auto; padding: 10px 14px;
  font: 400 14px/1.65 var(--sans); color: var(--ink);
  background: #fffdf9; border: 1px solid #dcd4c3; border-radius: var(--r-s);
  outline: none; box-sizing: border-box; white-space: pre-wrap; word-break: break-word;
  overflow: visible; cursor: text;
}
.doc-raw-editor:focus {
  background: #ffffff; border-color: var(--ink);
  box-shadow: 0 0 0 2px rgba(23, 21, 15, 0.08);
}
.doc-raw-editor:focus {
  background: #fff; border-color: var(--ink);
}
.doc-edit-actions {
  display: flex; justify-content: flex-end; margin-top: 6px;
}

.doc-prob-footer {
  display: flex; justify-content: flex-end; margin-top: 4px;
}
.btn-doc-ai {
  border: 1px solid #fde047; background: #fefce8; padding: 0 7px;
  height: 22px; font: 600 11px/1 var(--sans); color: #854d0e;
  cursor: pointer; border-radius: var(--r-s); transition: all .12s;
  display: inline-flex; align-items: center; gap: 3px;
}
.btn-doc-ai:hover {
  background: #fef08a; border-color: #eab308; color: #713f12;
}

.doc-ai-drawer {
  background: #fffdf5; border: 1px solid #fef08a; border-radius: 6px;
  padding: 10px 12px; margin: 8px 0 10px; display: grid; gap: 8px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.03);
}
.doc-ai-head {
  display: flex; flex-direction: column; gap: 2px;
}
.doc-ai-head b {
  font: 600 12px/1.3 var(--sans); color: #854d0e;
}
.doc-ai-desc {
  font: 400 11.5px/1.4 var(--sans); color: var(--ink-2);
}
.doc-ai-input {
  width: 100%; border: 1px solid var(--line-2); border-radius: 4px;
  padding: 8px 10px; font: 400 12.5px/1.5 var(--mono); color: var(--ink);
  background: #fff; resize: vertical; min-height: 56px;
}
.doc-ai-input:focus {
  outline: none; border-color: #eab308; box-shadow: 0 0 0 2px rgba(234, 179, 8, 0.2);
}
.doc-ai-actions {
  display: flex; justify-content: flex-end; gap: 8px;
}

.pg-head { position: sticky; top: 0; z-index: 4; background: var(--sheet); }

.pg-bar { display: flex; align-items: center; width: 100%; }

.pg-bar .pg-title { flex: 1; min-width: 0; }

.pg-sec-solve {
  display: inline-flex; align-items: center; gap: 4px;
  height: 22px; padding: 0 8px; margin-right: 6px;
  border: 1px solid var(--line-2); border-radius: var(--r-s);
  background: #fff; font: 500 11px/1 var(--sans); color: #92540c;
  cursor: pointer; transition: background .12s, border-color .12s; flex: none;
}
.pg-sec-solve:hover {
  background: #fdf5e2; border-color: #f0db9a;
}

.pg-fold {
  flex: none; display: flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; margin-right: 12px;
  border: 1px solid transparent; border-radius: var(--r-s);
  background: transparent; color: var(--ink-3); cursor: pointer;
  transition: color .12s, background .12s, border-color .12s;
}

.pg-fold:hover { color: var(--ink); background: var(--paper); border-color: var(--line-2); }

.pg-fold svg { transition: transform .18s; }

.pg.is-folded .pg-fold svg { transform: rotate(0deg); }

.pg:not(.is-folded) .pg-fold svg { transform: rotate(180deg); }

.pg.is-folded > .q { display: none !important; }

.pg.is-folded .pg-scroll { display: none; }

.pg-title {

  display: grid; grid-template-columns: auto minmax(0, 1fr) auto auto;

  align-items: center; gap: 10px; width: 100%;

  padding: 9px 14px 7px 18px; border: 0; background: none; cursor: pointer; text-align: left;

}

.pg-title:hover { background: var(--paper); }

.pg-title > b { font: 600 12.5px/1 var(--mono); }

.pg-title > span { font: 400 14px/1.25 var(--serif); color: var(--ink);

  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.pg-track { height: 3px; background: var(--line-2); border-radius: 0; }

.pg-track .seg { transition: width .28s ease; }

.pg-count { font: 400 10.5px/1 var(--mono); font-style: normal; color: var(--ink-3); }

.pg-caret { width: 0; height: 0; border: 4px solid transparent; border-top-color: var(--ink-3);

  margin-top: 4px; transition: transform .15s; }

.pg-title.open .pg-caret { transform: rotate(180deg); }



.pg-grid {

  display: flex; flex-wrap: wrap; gap: 4px;

  padding: 2px 14px 10px 18px; border-top: 1px solid var(--line);

}

.gq {

  min-width: 30px; height: 26px; padding: 0 7px;

  font: 500 11.5px/1 var(--mono); color: var(--ink-2);

  background: #fff; border: 1px solid var(--line); border-radius: var(--r-s);

  border-left-width: 3px; cursor: pointer; transition: border-color .12s, background .12s;

}

.gq:hover { border-color: var(--ink-3); color: var(--ink); }

.gq.is-todo { border-left-color: var(--todo); }

.gq.is-doing { border-left-color: var(--doing); }

.gq.is-done { border-left-color: var(--done); background: #eef7f1; color: var(--done); }

.gq.is-stuck { border-left-color: var(--stuck); background: #fdf1f1; }

.gq.is-extra { box-shadow: 0 0 0 1.5px #d97706; }

.gq.is-unmentioned { border-style: dashed; opacity: 0.55; }



/* how far through THIS section you have scrolled, which the browser

   scrollbar cannot tell you when the document is 563 problems long */

.pg-scroll { height: 2px; background: var(--paper-3); }

.pg-scroll > i { display: block; height: 100%; width: 0; background: var(--ink);

  transition: width .08s linear; }



.q { display: grid; grid-template-columns: 66px 1fr; align-items: stretch;

  padding: 0 14px 0 0; border-bottom: 1px solid var(--line); }

.q.current { background: linear-gradient(90deg, rgba(240,227,189,.30), rgba(240,227,189,.06) 60%, transparent); }

.q:last-child { border-bottom: 0; }

/* Collapsed question block */
.q.is-collapsed {
  min-height: 38px;
  background: rgba(245, 242, 234, 0.45);
  transition: background .12s;
}

.q.is-collapsed:hover {
  background: var(--paper-2);
}

.q.is-collapsed.current {
  background: linear-gradient(90deg, rgba(240,227,189,.35), rgba(240,227,189,.10) 60%, transparent);
}

.q.is-collapsed .q-body {
  display: none !important;
}

.q:not(.is-collapsed) .q-collapsed-bar {
  display: none !important;
}

.q-collapsed-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 0 14px 0 14px;
  min-height: 38px;
  cursor: pointer;
  user-select: none;
}

.q-collapsed-preview {
  flex: 1;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  font: 400 13px/1.3 var(--serif);
  color: var(--ink-2);
}

.q-collapsed-preview .katex {
  font-size: 1.05em;
}

.q-collapsed-meta {
  flex: none;
  display: flex;
  align-items: center;
  gap: 8px;
}

.q-collapsed-badge {
  font: 600 10px/1 var(--sans);
  padding: 2px 7px;
  border-radius: 99px;
  letter-spacing: 0.02em;
}

.q-collapsed-badge.is-extra {
  background: #fdf3df;
  color: #92540c;
  border: 1px solid #eecf97;
}

.q-collapsed-badge.is-unmentioned {
  background: #f1ede3;
  color: #8c8270;
  border: 1px dashed #c8beab;
}

.q-badge {
  display: inline-block;
  padding: 1px 4px;
  font: 600 8.5px/1 var(--sans);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-radius: 3px;
  text-align: center;
  max-width: 58px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.q-badge.is-extra {
  background: #fdf3df;
  color: #92540c;
  border: 1px solid #eecf97;
}

.q-badge.is-unmentioned {
  background: #f1ede3;
  color: #8c8270;
  border: 1px dashed #c8beab;
}

.q-badge.is-custom {
  background: #eef1f8;
  color: #2b499d;
  border: 1px solid #ccd8f1;
}

.q-collapsed-count {
  font: 500 11px/1 var(--mono);
  padding: 2px 7px;
  border-radius: 99px;
  background: rgba(46, 125, 50, 0.10);
  color: var(--done);
}

.q-collapsed-cue {
  font: 500 11.5px/1 var(--serif);
  color: var(--ink-3);
  letter-spacing: 0.02em;
  transition: color .12s;
}

.q-collapsed-bar:hover .q-collapsed-cue {
  color: var(--ink);
}

.q-fold {
  width: 24px; height: 22px; display: grid; place-items: center; border-radius: var(--r-s);
  color: var(--ink-3); border: 1px solid transparent;
  transition: color .12s, background .12s, border-color .12s;
}

.q-fold:hover { color: var(--ink); background: #fff; border-color: var(--line-2); }

.q-fold svg { transition: transform .15s; }

.q.is-collapsed .q-fold svg { transform: rotate(180deg); }

.q.is-collapsed .q-margin {
  flex-direction: row;
  justify-content: center;
  align-items: center;
  gap: 7px;
  padding: 4px 6px;
}

.q.is-collapsed .q-tools {
  display: none;
}

.q-margin {

  display: flex; flex-direction: column; align-items: center; gap: 4px;

  padding: 8px 2px 8px 2px; border-right: 1px solid var(--line);
  width: 66px; overflow: hidden; box-sizing: border-box;

}

.q-num { position: relative; }

.q-star { position: absolute; top: -5px; right: -11px; font-size: 9px;

  font-style: normal; color: var(--todo); opacity: 0; transition: opacity .12s; }

.q.starred .q-star { opacity: 1; }

.q-tools {
  display: grid;
  grid-template-columns: repeat(2, 22px);
  gap: 3px;
  justify-content: center;
  align-items: center;
  width: 48px;
}

.q-margin button { border: 0; background: none; cursor: pointer; padding: 0; }

.q-book, .q-more, .q-ai-btn, .q-fold {

  width: 22px; height: 22px; display: grid; place-items: center; border-radius: var(--r-s);

  color: var(--ink-3); border: 1px solid transparent;

  transition: color .12s, background .12s, border-color .12s;

}

.q-book:hover, .q-more:hover { color: var(--ink); background: #fff; border-color: var(--line-2); }

.q-ai-btn { font-size: 11px; }

.q-ai-btn:hover { background: #fdf5e2; color: #92540c; border-color: #f0db9a; }

.q-more.has-note { color: var(--doing); }

.q-more.off-track { color: var(--todo); }

.q-more.has-note.off-track { color: var(--stuck); }

.q-num { font: 600 14px/1 var(--serif); color: var(--ink); }

.pin { width: 15px; height: 15px; padding: 0; border-radius: 50%; cursor: pointer;

  border: 2px solid #b8b2a4; background: #ded8ca;

  transition: box-shadow .14s, background .14s, border-color .14s; }

.pin:hover { border-color: var(--ink-3); box-shadow: 0 0 0 3px rgba(23,21,15,.12); }

.pin.is-todo { border-color: #b8b2a4; background: #ded8ca; }

.pin.is-doing { border-color: var(--doing);

  background: linear-gradient(90deg, var(--doing) 50%, #dfe6f7 50%); }

.pin.is-done { border-color: var(--done); background: var(--done); }

.pin.is-stuck { border-color: var(--stuck); background: var(--stuck); }



/* written on but never marked: a slow ring, so it nags without shouting */

.pin.nudge { animation: nudge 2.1s ease-out infinite; }

@keyframes nudge {

  0%   { box-shadow: 0 0 0 0 rgba(201, 138, 16, .55); }

  70%  { box-shadow: 0 0 0 8px rgba(201, 138, 16, 0); }

  100% { box-shadow: 0 0 0 0 rgba(201, 138, 16, 0); }

}

@media (prefers-reduced-motion: reduce) { .pin.nudge { animation: none; border-color: var(--todo); } }



.q-body {
  padding: 6px 14px 8px 14px;
  min-height: 32px;
  cursor: text;
  display: flex;
  flex-direction: column;
  gap: 3px;
  line-height: 1.55;
}

/* Fluid document canvas rows: clean, continuous, natural spacing */
.ln {
  position: relative; display: flex; flex-wrap: wrap;
  align-items: baseline; gap: 6px 12px;
  min-height: 26px;
  padding: 2px 6px; border-radius: var(--r-s);
  transition: background .12s;
}
.ln:hover { background: rgba(23, 21, 15, .025); }
.ln.on, .ln:focus-within { background: #fffdf8; }
.ln::before {
  content: ""; position: absolute; left: -2px; top: 4px; bottom: 4px; width: 2px;
  border-radius: 1px; background: transparent; transition: background .12s;
}
.ln:hover::before { background: var(--line-2); }
.ln.on::before, .ln:focus-within::before { background: var(--ink); }

.cell {
  position: relative; display: inline-flex; align-items: baseline; min-width: 0;
  padding: 1px 6px; border-radius: var(--r-s);
  border-bottom: none;
}
.cell + .cell { border-left: none; padding-left: 6px; }
.cell:hover { background: transparent; }
.cell:focus-within { background: rgba(240, 227, 189, .25); }
.cell > math-field, .cell > .prose {
  min-width: 0; display: inline-flex; align-items: baseline;
}
.cell.is-text, .cell .prose { font: 400 13.5px/1.55 var(--sans); color: var(--ink-2); }
.prose { outline: none; }
.prose:empty::before { content: "write or click 💡..."; color: var(--line-2); font-style: italic; font-size: 12px; }
.cell.is-plot { border-bottom: 0; padding-block: 6px; }

.cell-drop {
  position: absolute; right: 2px; top: 50%; transform: translateY(-50%);
  width: 15px; height: 17px; padding: 0; border: 0; border-radius: 3px;
  font: 500 12px/1 var(--mono); color: var(--ink-3);
  background: transparent; cursor: pointer; opacity: 0; transition: opacity .12s;
}
.cell:hover .cell-drop, .cell:focus-within .cell-drop { opacity: 1; }
.cell-drop:hover { color: var(--ink); background: var(--paper-3); }

math-field {
  font-size: 16px; outline: none;
  border: 0; border-radius: 0; background: transparent; padding: 0 2px;
  --caret-color: var(--ink);
  --selection-background-color: #f0e3bd;
  --contains-highlight-background-color: transparent;
}
math-field::part(virtual-keyboard-toggle), math-field::part(menu-toggle) { display: none; }




/* -------------------------------------------------------------- dock */

.dock { flex: none; display: flex; flex-direction: column;

  border-top: 1px solid var(--line-2); background: var(--paper-2); }

#workspace[data-kbd="off"] .dock-slot,

#dock[data-tab="graph"] .dock-slot,

#dock[data-state="closed"] .dock-slot { display: none !important; }

#dock[data-state="closed"] .dock-graph { display: none !important; }

.dock-bar { display: flex; align-items: center; gap: 12px; padding: 0 10px 0 0; background: var(--paper-2); }

.dock-grip { flex: 1; height: 14px; display: grid; place-items: center;

  background: none; border: 0; cursor: pointer; }

.dock-tabs { display: flex; gap: 2px; padding: 2px 0; }

.dock-tabs button {

  height: 20px; padding: 0 10px; border: 0; border-radius: 99px;

  font: 500 11px/1 var(--sans); color: var(--ink-3);

  background: transparent; cursor: pointer;

}

.dock-tabs button:hover { color: var(--ink); background: var(--paper-3); }

.dock-tabs button.on { background: var(--ink); color: var(--paper); }

.dock-grip span { width: 34px; height: 3px; border-radius: 2px; background: var(--line-2); display: block; }

.dock-grip:hover span { background: var(--ink-3); }

.dock-slot { position: relative; height: var(--dock); max-height: 52vh; overflow: hidden; }

/* MathLive fills its container absolutely, so the container has to be told how

   tall the active board is; fitDock() in app.js measures it and sets --dock */

.dock-slot .ML__keyboard { position: absolute !important; inset: 0 !important; }



#kbdDock {

  --keyboard-background: var(--paper);

  --keyboard-border: var(--line);

  --keyboard-horizontal-rule: var(--line);

  --keyboard-padding-top: 0px;

  --keyboard-padding-bottom: 3px;

  --keyboard-padding-horizontal: 8px;

  --keyboard-toolbar-background: var(--paper);

  --keyboard-toolbar-background-hover: var(--paper-3);

  --keyboard-toolbar-background-selected: transparent;

  --keyboard-toolbar-text: var(--ink-3);

  --keyboard-toolbar-text-active: var(--ink);

  --keyboard-toolbar-font-size: 12px;

  --keycap-background: #fff;

  --keycap-background-hover: #fff;

  --keycap-background-active: var(--ink);

  --keycap-background-pressed: var(--paper-3);

  --keycap-border: var(--line);

  --keycap-border-bottom: var(--line-2);

  --keycap-text: var(--ink);

  --keycap-text-hover: var(--ink);

  --keycap-secondary-background: var(--paper-3);

  --keycap-secondary-background-hover: var(--paper-2);

  --keycap-secondary-text: var(--ink-2);

  --keycap-secondary-border: var(--line);

  --keycap-secondary-border-bottom: var(--line-2);

  --keycap-primary-background: var(--ink);

  --keycap-primary-text: var(--paper);

  --keycap-height: 38px;

  --keycap-gap: 4px;

  --keycap-font-size: 15px;

  --keycap-shift-color: var(--ink-3);

}



/* -------------------------------------------------------------- zoom */

.zoomer {

  position: absolute; right: 14px; bottom: 12px; z-index: 12;

  display: flex; align-items: center; gap: 1px; padding: 3px;

  background: rgba(250,248,244,.9); backdrop-filter: blur(8px);

  border: 1px solid var(--line-2); border-radius: 99px; box-shadow: var(--shadow-1);

  opacity: .5; transition: opacity .16s;

}

.pane-book:hover .zoomer { opacity: 1; }

.zoomer button {

  height: 22px; min-width: 24px; padding: 0 7px; border: 0; border-radius: 99px;

  font: 500 11px/1 var(--mono); color: var(--ink-2); background: transparent; cursor: pointer;

}

.zoomer button:hover { background: var(--paper-3); color: var(--ink); }



/* ---------------------------------------------------------- tag popover */

.tagpop {

  position: fixed; z-index: 70; width: 236px; padding: 8px;

  background: #fff; border: 1px solid var(--line-2); border-radius: var(--r);

  box-shadow: var(--shadow-3);

}

.tagpop-labels { display: grid; grid-template-columns: 1fr 1fr; gap: 3px; margin-bottom: 7px; }

.tl {

  display: flex; align-items: center; gap: 6px; padding: 5px 7px;

  font: 400 11.5px/1 var(--sans); color: var(--ink-2);

  background: var(--paper); border: 1px solid transparent; border-radius: var(--r-s);

  cursor: pointer; text-align: left;

}

.tl:hover { border-color: var(--line-2); color: var(--ink); }

.tl.on { background: var(--ink); color: var(--paper); }

.tagpop-presets { display: flex; gap: 4px; margin-bottom: 7px; }

.btn-preset {
  flex: 1; height: 22px; padding: 0 4px; font: 500 10px/1 var(--sans);
  background: var(--paper-2); border: 1px solid var(--line-2); border-radius: var(--r-s);
  color: var(--ink-2); cursor: pointer; transition: background .12s, color .12s;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}

.btn-preset:hover { background: var(--ink); color: #fff; border-color: var(--ink); }

.btn-preset.clear:hover { background: var(--stuck); color: #fff; border-color: var(--stuck); }

.tagpop-note {

  width: 100%; padding: 7px 8px; resize: vertical;

  font: 400 12px/1.5 var(--serif); color: var(--ink);

  border: 1px solid var(--line-2); border-radius: var(--r-s); background: var(--paper);

}

.tagpop-note:focus { outline: none; border-color: var(--ink); background: #fff; }

.tagpop-foot { display: flex; align-items: center; gap: 8px; margin-top: 7px; }

.tagpop-foot span { font: 400 10px/1 var(--mono); color: var(--ink-3); }

.tagpop-foot .btn { margin-left: auto; height: 24px; padding: 0 10px; font-size: 11.5px; }



/* --------------------------------------------------------------- drawer */

.drawer-veil { position: absolute; inset: 0; z-index: 44; background: rgba(23,21,15,.24); }

.drawer {

  position: absolute; left: 0; top: 0; bottom: 0; width: 320px; z-index: 45;

  display: flex; flex-direction: column;

  background: var(--paper); border-right: 1px solid var(--line-2);

  box-shadow: 18px 0 44px -26px rgba(23,21,15,.65);

  animation: slide-in .16s ease-out;

}

@keyframes slide-in { from { transform: translateX(-14px); opacity: .6; } }

.drawer-head { display: flex; align-items: center; gap: 9px; padding: 11px 8px 11px 16px;

  border-bottom: 1px solid var(--line); background: var(--paper-2); }

.drawer-head b { font: 500 13px/1 var(--sans); }

.drawer-head span { font: 400 10.5px/1 var(--mono); color: var(--ink-3); }

.drawer-head .icon { margin-left: auto; }

.drawer-search { padding: 9px 12px; border-bottom: 1px solid var(--line); }

.drawer-set-picker {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 12px; background: var(--sheet);
  border-bottom: 1px solid var(--line);
}

.drawer-set-label {
  font: 500 11px/1 var(--sans); color: var(--ink-3); text-transform: uppercase; letter-spacing: 0.04em; flex: none;
}

.drawer-set-picker .select {
  flex: 1; height: 26px; font-size: 11.5px; padding: 0 24px 0 8px; border-radius: var(--r-s);
}

.drawer-tree { flex: 1; overflow-y: auto; padding: 4px 0 20px; }

.drawer-foot { display: grid; gap: 4px; padding: 9px 12px; border-top: 1px solid var(--line);

  background: var(--paper-2); }

.drawer-foot .btn { justify-content: flex-start; height: 28px; font-size: 12px; }

#railProfile { font-weight: 600; }



.tchap { border-bottom: 1px solid var(--line); }

.tchap > summary { display: flex; align-items: center; gap: 7px; padding: 8px 12px 5px;

  cursor: pointer; list-style: none; }

.tchap > summary::-webkit-details-marker { display: none; }

.tchap > summary:hover { background: var(--paper-2); }

.tw { width: 0; height: 0; border: 4px solid transparent; border-left-color: var(--ink-3);

  transition: transform .15s; transform-origin: 25% 50%; flex: none; }

.tchap[open] .tw { transform: rotate(90deg); }

.tchap > summary b { flex: none; font: 600 11.5px/1 var(--mono); }

.tchap > summary span { flex: 1; font-size: 11.5px; color: var(--ink-2);

  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.tchap > summary em { font: 400 10px/1 var(--mono); font-style: normal; color: var(--ink-3); }

.tchap-track { display: flex; height: 3px; margin: 0 12px 6px; border-radius: 2px;

  background: var(--line); overflow: hidden; }



.tsec { padding: 0 12px 8px 20px; border-left: 2px solid transparent; }

.tsec.on { border-left-color: var(--ink); background: var(--paper-2); }

.tsec-head { display: flex; align-items: baseline; gap: 6px; width: 100%;

  padding: 3px 4px; border: 0; background: none; cursor: pointer; text-align: left;

  border-radius: var(--r-s); color: var(--ink); }

.tsec-head:hover { background: var(--paper-3); }

.tsec-head b { flex: none; font: 600 11px/1 var(--mono); }

.tsec-head span { flex: 1; font-size: 11px; color: var(--ink-2);

  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.tsec-head em { font: 400 9.5px/1 var(--mono); font-style: normal; color: var(--ink-3); }

.tsec-track { display: flex; height: 3px; margin: 2px 4px 5px; border-radius: 2px;

  background: var(--line); overflow: hidden; }

.tpins { display: flex; flex-wrap: wrap; gap: 3px; padding-left: 4px; }

.tp { min-width: 22px; height: 19px; padding: 0 4px;

  font: 500 10px/1 var(--mono); color: var(--ink-2);

  background: #fff; border: 1px solid var(--line); border-radius: 3px; cursor: pointer;

  border-left-width: 3px; }

.tp:hover { border-color: var(--ink-3); color: var(--ink); }

.tp.is-todo { border-left-color: var(--todo); }

.tp.is-doing { border-left-color: var(--doing); }

.tp.is-done { border-left-color: var(--done); background: #f1f8f3; }

.tp.is-stuck { border-left-color: var(--stuck); background: #fdf2f2; }

.tp.is-extra { box-shadow: 0 0 0 1.5px #d97706; }

.tp.is-unmentioned { border-style: dashed; opacity: 0.55; }



/* ------------------------------------------------------------ picker */

.picker { position: fixed; z-index: 60; display: grid; padding: 4px; background: #fff;

  border: 1px solid var(--line-2); border-radius: var(--r); box-shadow: var(--shadow-2); }

.picker button { display: flex; align-items: center; gap: 8px; padding: 6px 12px 6px 8px;

  font: 400 12px/1 var(--sans); color: var(--ink); background: none; border: 0;

  border-radius: var(--r-s); cursor: pointer; text-align: left; }

.picker button:hover { background: var(--paper-2); }



/* -------------------------------------------------------------- boot */

.boot { position: absolute; inset: 0; display: grid; place-items: center; background: var(--paper); z-index: 30; }

.boot p { font: 400 13px/1 var(--sans); color: var(--ink-2); }



/* ----------------------------------------------------------- dialogs */

dialog { width: min(880px, 94vw); max-height: 88vh; padding: 0; border: 0; border-radius: 12px;

  background: var(--paper); color: var(--ink); box-shadow: var(--shadow-3); }

dialog#exportDlg { width: min(620px, 94vw); }

dialog::backdrop { background: rgba(23, 21, 15, .38); backdrop-filter: blur(2px); }

.dlg-head { display: flex; align-items: center; gap: 16px; padding: 14px 18px;

  border-bottom: 1px solid var(--line-2); background: var(--paper-2); border-radius: 12px 12px 0 0; }

.dlg-head h2 { margin: 0; font: 400 17px/1 var(--serif); }

.tabs { display: flex; gap: 2px; margin-left: auto; }

.tab { height: 28px; padding: 0 13px; border: 0; border-radius: var(--r);

  font: 500 12.5px/1 var(--sans); color: var(--ink-2); background: transparent; cursor: pointer; }

.tab:hover { background: var(--paper-3); color: var(--ink); }

.tab.on { background: var(--ink); color: var(--paper); }

.panel { padding: 18px; overflow-y: auto; max-height: calc(88vh - 60px); }

.panel h3 { margin: 0 0 8px; font: 500 13px/1 var(--sans); }

.split { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; margin-top: 18px; }

.split .btn { margin-top: 8px; }

.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }

.fieldset { display: grid; gap: 5px; }

.fieldset > span { font: 500 10.5px/1 var(--sans); letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); }

.rowbtns { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-top: 14px; }

.rowbtns.end { justify-content: flex-end; }

.email-input-wrap { margin-bottom: 12px; }

.email-options { display: grid; gap: 8px; margin: 12px 0; }

.cb-label {
  display: flex; align-items: center; gap: 8px;
  font: 400 12.5px/1.3 var(--sans); color: var(--ink-2); cursor: pointer;
}

.cb-label input { cursor: pointer; accent-color: var(--ink); }

.cb-label em { font-style: normal; font-weight: 500; color: var(--ink); }

.email-diff {
  margin-top: 14px; padding: 14px; background: var(--sheet);
  border: 1px solid var(--line-2); border-radius: var(--r);
}

.diff-summary-bar {
  padding: 8px 12px; margin-bottom: 12px; background: var(--paper-2);
  border: 1px solid var(--line-2); border-radius: var(--r-s);
  font: 400 12.5px/1.4 var(--sans); color: var(--ink);
}

.diff-summary-bar b { font-weight: 600; color: var(--ink); }

.email-diff h3 { margin: 0 0 10px; font: 500 13px/1 var(--sans); }

.diff-sec { padding: 9px 0; border-bottom: 1px solid var(--line); }

.diff-sec:last-child { border-bottom: 0; }

.diff-sec-head { margin-bottom: 5px; font: 500 12.5px/1.3 var(--sans); color: var(--ink); }

.diff-sec-head b { font-family: var(--mono); }

.diff-sec-head span { font-size: 11px; color: var(--ink-3); margin-left: 6px; }

.diff-row {
  display: flex; align-items: baseline; gap: 6px; padding: 3px 0;
  font-size: 12px;
}

.diff-row b { font-size: 11px; }

.diff-row.is-extra { color: #92540c; }

.diff-row.is-omitted { color: #706859; }

.diff-row.is-confirmed { color: var(--done); }



.plist { display: grid; gap: 6px; }

.prow { display: flex; align-items: center; gap: 12px; padding: 10px 12px; background: #fff;

  border: 1px solid var(--line); border-radius: var(--r); }

.prow.on { border-color: var(--ink-3); box-shadow: 0 0 0 3px rgba(23,21,15,.06); }

.prow b { display: block; font: 500 13px/1.3 var(--sans); }

.prow small { display: block; font: 400 11px/1.4 var(--mono); color: var(--ink-3); }

.prow-acts { display: flex; gap: 4px; margin-left: auto; }

.prow-acts .btn { height: 26px; padding: 0 9px; font-size: 11.5px; }



.blist { display: grid; gap: 6px; }

.brow { display: flex; align-items: center; gap: 16px; padding: 9px 12px; background: #fff;

  border: 1px solid var(--line); border-radius: var(--r); }

.brow b { font: 500 12.5px/1.3 var(--sans); }

.brow small { display: block; font-size: 11px; color: var(--ink-3); }

.chips { display: flex; flex-wrap: wrap; gap: 4px; margin-left: auto; }

.chip { display: inline-flex; align-items: center; gap: 5px; height: 26px; padding: 0 10px;

  font: 500 11.5px/1 var(--sans); color: var(--ink-2); background: var(--paper-2);

  border: 1px solid var(--line); border-radius: 99px; cursor: pointer; }

.chip:hover { border-color: var(--ink-3); color: var(--ink); }

.chip.on { background: var(--ink); border-color: var(--ink); color: var(--paper); }

.chip i { font: 600 9.5px/1 var(--mono); font-style: normal; padding: 2px 4px;

  border-radius: 99px; background: rgba(250,248,244,.24); }



/* -------------------------------------------------------- print view */

#printView { position: absolute; left: -10000px; top: 0; width: 190mm; background: #fff; color: #000; }

.pv-head { border-bottom: 2px solid #000; padding-bottom: 8px; margin-bottom: 18px; }

.pv-head h1 { margin: 0; font: 400 22px/1.2 var(--serif); }

.pv-head p { margin: 4px 0 0; font: 400 11px/1 var(--sans); color: #555; }

.pv-sec { margin: 22px 0 10px; padding-bottom: 5px; border-bottom: 1px solid #999;

  font: 400 15px/1.2 var(--serif); break-after: avoid; }

.pv-sec b { font-family: var(--mono); font-size: 13px; margin-right: 8px; }

.pv-q { display: grid; grid-template-columns: 46px 1fr; gap: 10px; margin: 0 0 12px; break-inside: avoid; }

.pv-n { font: 600 14px/1.4 var(--serif); }

.pv-n i { display: block; font: 400 8.5px/1.4 var(--sans); font-style: normal;

  text-transform: uppercase; letter-spacing: .06em; color: #888; }

.pv-body { border-left: 1px solid #ddd; padding-left: 12px; }

.pv-math { margin: 3px 0; font-size: 15px; }

.pv-text { margin: 3px 0; font: 400 12.5px/1.55 var(--serif); }



@media print {

  body { overflow: visible; background: #fff; }

  body[data-printing] > *:not(#printView) { display: none !important; }

  #printView { position: static !important; left: auto !important; width: auto; }

  @page { margin: 16mm 14mm; }

}



/* -------------------------------------------------------- responsive */

@media (max-width: 1200px) { .jump-btn { max-width: 160px; } }

@media (max-width: 980px) {

  #workspace { flex-direction: column; }

  .rail-panel { width: 262px; }

  .pane-book { flex: 0 0 42vh; order: 1 !important; }

  .pane-sheet { flex: 1 1 0; order: 3 !important; }

  .splitter { display: none; }

  .hud { bottom: 10px; left: 10px; }

  .hud-progress { display: none; }

  .dock-slot { min-height: 168px; max-height: 40vh; }

}

@media (max-width: 620px) {

  .jump-btn span { display: none; }

  :root { --rail: 38px; }

  .rail-panel { width: calc(100vw - var(--rail)); }

  .ln.has-aside { grid-template-columns: 1fr; row-gap: 2px; }

  .ln-aside { border-left: 0; padding-left: 0; border-top: 1px solid var(--line); }

  .q { grid-template-columns: 40px 1fr; padding-right: 8px; }

  .split, .grid2 { grid-template-columns: 1fr; }

}



/* MathLive leaves a generous band above its tabs; this is a writing tool and

   that band is screen we do not have */

#kbdDock .MLK__toolbar { min-height: 0; padding: 1px 4px 0; }

/* the plate is absolutely positioned by MathLive, which collapses our dock

   to nothing; put it back in flow so the dock is exactly as tall as the keys */

#kbdDock .MLK__plate { padding-top: 0; }

#kbdDock .MLK__rows { width: 100%; }

#kbdDock .MLK__keycap { min-width: 0; }



.gq.starred { position: relative; }

.gq.starred::after { content: "\2605"; position: absolute; top: -3px; right: -2px;

  font-size: 8px; color: var(--todo); }

.tl.star { width: 100%; justify-content: flex-start; margin-bottom: 7px; }

.tl.star i { font-style: normal; font-size: 13px; line-height: 1; color: var(--todo); }

.tl.star.on { background: var(--todo); border-color: var(--todo); color: #fff; }

.tl.star.on i { color: #fff; }



/* --------------------------------------------------------- graph panel */

.dock-graph { display: grid; grid-template-columns: minmax(0, 260px) minmax(0, 1fr);

  gap: 12px; padding: 10px 12px 12px; max-height: 46vh; overflow-y: auto; }

.gp-side { display: grid; gap: 7px; align-content: start; }

.gp-fns { display: grid; gap: 4px; }

.gp-fn { display: grid; grid-template-columns: 10px auto minmax(0, 1fr) 18px;

  align-items: center; gap: 6px; }

.gp-fn .swatch { width: 9px; height: 9px; border-radius: 2px; }

.gp-y { font: 400 12px/1 var(--serif); color: var(--ink-2); }

.gp-fn input {

  height: 26px; padding: 0 8px; width: 100%;

  font: 400 12.5px/1 var(--mono); color: var(--ink);

  background: #fff; border: 1px solid var(--line-2); border-radius: var(--r-s);

}

.gp-fn input:focus { outline: none; border-color: var(--ink); box-shadow: var(--ring); }

.gp-drop { width: 18px; height: 18px; padding: 0; border: 0; border-radius: 3px;

  color: var(--ink-3); background: none; cursor: pointer; }

.gp-drop:hover { color: var(--stuck); background: var(--paper-3); }

.gp-win { display: grid; gap: 4px; }

.gp-win label { display: flex; align-items: center; gap: 5px;

  font: 400 11px/1 var(--mono); color: var(--ink-3); }

.gp-win input { width: 100%; min-width: 0; height: 24px; padding: 0 6px;

  font: 400 11.5px/1 var(--mono); background: #fff;

  border: 1px solid var(--line); border-radius: var(--r-s); }

.gp-acts { display: flex; gap: 6px; }

.gp-acts .btn { height: 27px; font-size: 12px; }

.gp-msg { margin: 0; min-height: 15px; font: 400 11px/1.4 var(--sans); color: var(--ink-3); }

.gp-preview { margin: 0; min-height: 150px; }

.gp-preview canvas { display: block; width: 100%; height: 100%; min-height: 150px;

  border: 1px solid var(--line-2); border-radius: var(--r-s); background: #fff; }



/* a graph living inside an answer */



figure.plot { margin: 0; max-width: 460px; }

figure.plot canvas, figure.plot img {

  display: block; width: 100%; height: 240px; object-fit: contain;

  border: 1px solid var(--line-2); border-radius: var(--r-s); background: #fff;

}

figure.plot:focus { outline: none; }

figure.plot:focus canvas { border-color: var(--ink); box-shadow: var(--ring); }

figure.plot figcaption {

  padding: 4px 2px 0; font: 400 11px/1.4 var(--mono); color: var(--ink-3);

}

.pv-plot img { max-width: 420px; border: 1px solid #ddd; }



@media (max-width: 980px) {

  .dock-graph { grid-template-columns: minmax(0, 1fr); }

  .gp-preview canvas { height: 170px; }

}



/* ------------------------------------------------------- LaTeX boxes */

#workspace[data-layout="tex"] .paper-scroll,

#workspace[data-layout="tex"] .dock { display: none; }

#workspace[data-layout="tex"] .pane-book,

#workspace[data-layout="tex"] .splitter { display: flex; }

#workspace[data-layout="tex"] .pane-book { flex: 0 0 var(--split); }



.source-scroll { flex: 1; overflow-y: auto; background: var(--paper-2); padding: 0 9px 60px; }

.source { background: var(--sheet); border: 1px solid var(--line); border-top: 0;

  border-radius: 0 0 4px 4px; padding: 0 0 22px; }

.srcsec-head {

  position: sticky; top: 0; z-index: 4;

  display: flex; align-items: baseline; gap: 9px; padding: 10px 16px 8px 18px;

  background: var(--sheet); border-bottom: 1.5px solid var(--ink);

}

.srcsec-head b { flex: none; font: 600 12.5px/1 var(--mono); }

.srcsec-head span { font: 400 14px/1.25 var(--serif); color: var(--ink);

  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }



.src-q { display: grid; grid-template-columns: 52px 1fr; gap: 0;

  padding: 10px 16px 12px 0; border-bottom: 1px solid var(--line); }

.src-num { display: flex; flex-direction: column; align-items: center; gap: 5px;

  padding-top: 2px; border-right: 1px solid var(--line); }

.src-num b { font: 600 14px/1 var(--serif); }

.src-book { font: 400 8.5px/1 var(--sans); letter-spacing: .05em; text-transform: uppercase;

  color: var(--ink-3); background: none; border: 0; cursor: pointer; }

.src-book:hover { color: var(--ink); }

.src-body { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);

  gap: 12px; padding-left: 14px; }

.src-code {

  width: 100%; min-height: 58px; padding: 8px 10px; resize: vertical;

  font: 400 12px/1.65 var(--mono); color: var(--ink); tab-size: 2;

  background: var(--paper); border: 1px solid var(--line-2); border-radius: var(--r-s);

}

.src-code:focus { outline: none; background: #fff; border-color: var(--ink); box-shadow: var(--ring); }

.src-code::placeholder { color: var(--line-2); }

.src-preview { min-width: 0; padding: 4px 2px; overflow-x: auto; }

.src-math { margin: 2px 0; font-size: 15px; }

.src-text { margin: 2px 0; font: 400 13px/1.6 var(--serif); color: var(--ink-2); }

.src-aside { margin-left: 10px; padding-left: 10px; border-left: 1px solid var(--line);

  font: 400 11.5px/1.5 var(--serif); color: var(--ink-3); }

.src-err { margin: 2px 0; font: 400 11px/1.4 var(--mono); color: var(--stuck); }

.src-empty { margin: 2px 0; font: 400 11.5px/1 var(--sans); color: var(--line-2); }



@media (max-width: 1100px) { .src-body { grid-template-columns: minmax(0, 1fr); } }



/* ------------------------------------------------------ pane switcher */

.slots { display: inline-flex; align-items: center; gap: 2px; padding: 2px;

  background: var(--paper-3); border-radius: 99px; }

.slot {

  height: 22px; min-width: 54px; padding: 0 10px; border: 0; border-radius: 99px;

  font: 500 11.5px/1 var(--sans); color: var(--ink); background: #fff;

  box-shadow: var(--shadow-1); cursor: pointer; transition: color .12s, background .12s;

}

.slot:hover { background: var(--ink); color: var(--paper); }

.slot.muted { background: transparent; color: var(--ink-3); box-shadow: none; }

.icon.tight { width: 22px; height: 22px; font-size: 12px; }

.icon.on { background: var(--ink); color: var(--paper); }



/* the sheet pane keeps its own bottom dock; the LaTeX pane never has one */

.pane-tex .source-scroll { flex: 1; }


/* the controls must never be behind something you opened */
#workspace[data-drawer] .hud { left: 334px; }
@media (max-width: 700px) { #workspace[data-drawer] .hud { display: none; } }

/* the LaTeX preview and the printout mirror the same row of cells */
.src-line, .pv-line { display: grid; grid-template-columns: repeat(var(--cells, 1), minmax(0, 1fr));
  gap: 10px; align-items: center; }
.src-line > * + *, .pv-line > * + * { border-left: 1px solid var(--line); padding-left: 10px; }

/* -------------------------------------------------------- solution drawer */
.solution-drawer {
  position: fixed; right: 0; top: 0; bottom: 0; width: min(540px, 92vw); z-index: 65;
  display: flex; flex-direction: column;
  background: var(--paper); border-left: 1px solid var(--line-2);
  box-shadow: -16px 0 44px -20px rgba(23, 21, 15, .45);
  animation: sol-slide-in .18s cubic-bezier(0.16, 1, 0.3, 1);
}
@keyframes sol-slide-in { from { transform: translateX(100%); } }

.sol-head {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: 12px 16px; border-bottom: 1px solid var(--line-2); background: var(--paper-2);
}
.sol-nav {
  display: flex; align-items: center; gap: 8px; flex: 1; min-width: 0;
}
.sol-nav .btn.tight {
  width: 26px; height: 26px; padding: 0; font-size: 14px;
}
.sol-title {
  font: 500 13.5px/1.2 var(--sans); color: var(--ink);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.sol-body {
  flex: 1; overflow-y: auto; padding: 18px 20px; display: flex; flex-direction: column; gap: 16px;
}
.sol-topic {
  font: 600 12px/1 var(--sans); text-transform: uppercase; letter-spacing: 0.05em; color: var(--ink-3);
}
.sol-card {
  padding: 14px 16px; background: var(--sheet); border: 1px solid var(--line-2);
  border-radius: var(--r); box-shadow: var(--shadow-1);
}
.sol-card-label {
  font: 600 10.5px/1 var(--mono); text-transform: uppercase; letter-spacing: 0.06em;
  color: var(--ink-3); margin-bottom: 8px;
}
.sol-group {
  font: italic 13px/1.5 var(--serif); color: var(--ink-2); margin-bottom: 8px;
  padding-bottom: 8px; border-bottom: 1px solid var(--line);
}
.sol-statement {
  font: 500 15px/1.5 var(--serif); color: var(--ink);
}
.sol-steps-wrap {
  display: flex; flex-direction: column; gap: 10px;
}
.sol-step {
  display: grid; grid-template-columns: 24px 1fr; gap: 12px;
  padding: 12px 14px; background: var(--sheet); border: 1px solid var(--line);
  border-radius: var(--r);
}
.sol-step-n {
  width: 22px; height: 22px; border-radius: 50%;
  background: var(--paper-3); color: var(--ink-2);
  display: grid; place-items: center; font: 600 11px/1 var(--mono);
}
.sol-step-content {
  display: flex; flex-direction: column; gap: 6px; min-width: 0;
}
.sol-step-text {
  font: 400 12.5px/1.4 var(--sans); color: var(--ink-2);
}
.sol-step-math {
  font-size: 15px; color: var(--ink); overflow-x: auto; padding: 2px 0;
}
.sol-insight-card {
  background: #fbf8f0; border-color: #eeddb6;
}
.sol-insight-card .sol-card-label {
  color: #8c6812;
}
.sol-insight {
  font: 400 13px/1.5 var(--sans); color: #5a420b;
}
.sol-foot {
  padding: 12px 20px; border-top: 1px solid var(--line-2); background: var(--paper-2);
  display: flex; justify-content: flex-end; gap: 10px;
}
.sol-empty {
  padding: 40px 20px; text-align: center; color: var(--ink-2);
}
.sol-hint {
  font-size: 12px; color: var(--ink-3); margin-top: 8px;
}

/* --------------------------------------------------- batch solver dialog */
dialog.batch-solver-dlg {
  width: min(720px, 94vw);
  max-height: 88vh;
}
.batch-desc {
  font-size: 13px; line-height: 1.5; color: var(--ink-2);
  margin-bottom: 14px; padding-bottom: 12px; border-bottom: 1px solid var(--line);
}
.batch-filter-bar {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  margin-bottom: 12px; padding: 8px 12px; background: var(--paper-2);
  border: 1px solid var(--line-2); border-radius: var(--r);
}
.batch-filter-actions {
  display: flex; gap: 6px;
}
.btn.small {
  height: 24px; padding: 0 8px; font-size: 11px;
}
.batch-progress {
  margin-bottom: 14px; padding: 10px 14px; background: #fff;
  border: 1px solid var(--line); border-radius: var(--r);
}
.batch-progress-bar {
  height: 6px; background: var(--line-2); border-radius: 99px; overflow: hidden; margin-bottom: 6px;
}
#batchProgressFill {
  height: 100%; width: 0%; background: var(--done); transition: width .15s ease;
}
.batch-progress-text {
  font: 500 12px/1 var(--mono); color: var(--ink-2);
}
.batch-list {
  display: flex; flex-direction: column; gap: 14px; max-height: 48vh; overflow-y: auto;
  padding: 4px 2px 14px;
}
.batch-sec {
  border: 1px solid var(--line); border-radius: var(--r); background: #fff;
  padding: 10px 14px 14px;
}
.batch-sec-head {
  font: 500 13px/1.3 var(--sans); color: var(--ink); margin-bottom: 10px;
  padding-bottom: 6px; border-bottom: 1px solid var(--line);
}
.batch-sec-head b { font-family: var(--mono); }
.batch-sec-head span { font-size: 11.5px; color: var(--ink-3); margin-left: 6px; }
.batch-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(135px, 1fr)); gap: 8px;
}
.batch-item {
  display: flex; align-items: center; gap: 8px; padding: 6px 10px;
  border: 1px solid var(--line); border-radius: var(--r-s); background: var(--paper);
  cursor: pointer; transition: border-color .12s, background .12s;
  user-select: none;
}
.batch-item:hover {
  border-color: var(--ink-3); background: #fff;
}
.batch-item input[type="checkbox"] {
  cursor: pointer; accent-color: var(--ink); margin: 0;
}
.batch-item-content {
  display: flex; align-items: center; justify-content: space-between; flex: 1; min-width: 0; gap: 6px;
}
.batch-item-num {
  font: 600 12px/1 var(--mono); color: var(--ink);
}
.batch-status-pill {
  font: 500 10px/1 var(--sans); padding: 2px 6px; border-radius: 99px;
  letter-spacing: 0.02em; white-space: nowrap;
}
.batch-status-pill.is-solved {
  background: rgba(46, 125, 50, 0.12); color: var(--done);
}
.batch-status-pill.is-solving {
  background: rgba(51, 88, 196, 0.12); color: var(--doing);
  animation: pulse-solve 1s infinite alternate;
}
@keyframes pulse-solve { from { opacity: 0.6; } to { opacity: 1; } }
.batch-status-pill.is-queued {
  background: var(--paper-3); color: var(--ink-3);
}
.batch-view-btn {
  border: 0; background: transparent; font: 500 10px/1 var(--sans);
  color: var(--ink-3); cursor: pointer; padding: 2px 4px; border-radius: 2px;
}
.batch-view-btn:hover {
  color: var(--ink); background: var(--line);
}
.batch-options {
  margin-top: 12px; padding: 8px 12px; background: var(--paper-2);
  border-radius: var(--r-s); border: 1px solid var(--line);
}

.btn-share-hw {
  display: inline-flex; align-items: center; gap: 6px;
  height: 26px; padding: 0 12px; margin-left: auto;
  font: 500 11.5px/1 var(--sans); color: #fff; background: var(--ink);
  border: 1px solid var(--ink); border-radius: 99px; cursor: pointer;
  box-shadow: 0 1px 3px rgba(23, 21, 15, 0.15);
  transition: all .15s ease;
}
.btn-share-hw:hover {
  background: #332f28; transform: translateY(-1px);
}
.btn-share-hw.copied {
  background: var(--done); border-color: var(--done);
}

.book-loading-state {
  max-width: 320px; margin: 80px auto; padding: 24px;
  text-align: center; color: var(--ink-2); font: 400 13px/1.5 var(--sans);
  display: flex; flex-direction: column; align-items: center; gap: 12px;
}
.book-spinner {
  width: 24px; height: 24px; border: 2.5px solid var(--line-2);
  border-top-color: var(--ink); border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.book-empty-state {
  max-width: 380px; margin: 60px auto; padding: 28px 24px;
  text-align: center; background: #fff; border: 1px solid var(--line-2);
  border-radius: 8px; box-shadow: var(--shadow-1);
}
.book-empty-icon {
  font-size: 32px; margin-bottom: 12px;
}
.book-empty-state h3 {
  margin: 0 0 8px; font: 600 16px/1.3 var(--serif); color: var(--ink);
}
.book-empty-state p {
  margin: 0 0 10px; font: 400 12.5px/1.5 var(--sans); color: var(--ink-2);
}

.doc-welcome-card {
  max-width: 580px; margin: 40px auto; padding: 36px 32px;
  text-align: center; background: #fff; border: 1px solid var(--line-2);
  border-radius: 8px; box-shadow: var(--shadow-2);
}
.doc-welcome-card h2 {
  font: 400 24px/1.2 var(--serif); margin: 12px 0 10px; color: var(--ink);
}
.doc-welcome-card p {
  font: 400 13.5px/1.6 var(--sans); color: var(--ink-2); margin: 0 0 20px;
}
.welcome-badge {
  display: inline-block; font: 600 11px/1 var(--mono); text-transform: uppercase;
  padding: 3px 10px; background: var(--paper-3); color: var(--ink-2); border-radius: 99px;
}
.welcome-actions {
  display: flex; justify-content: center; gap: 12px;
}