/* ============================================================
   Intro DS AI — Exam Booklet
   Calm, focused study surface. Warm paper, ink type, a single red
   grading-pen accent. One uniform fine grain (no blotches). Newsreader
   (serif) for reading + JetBrains Mono for labels. Light + black-paper dark.
   ============================================================ */

:root {
  --paper:   #ece4d3;   /* warm paper, the room around the sheet */
  --sheet:   #f6f1e6;   /* the exam sheet — where you read */
  --sunk:    #e4dcca;   /* inputs / sunk wells */
  --ink:     #26221a;   /* warm near-black ink */
  --ink-2:   #5c5443;
  --faint:   #948a72;
  --line:    #ddd3bd;   /* hairlines / dividers */
  --line-2:  #cabfa4;
  --pen:     #b4202e;   /* the single accent — red grading pen */
  --pen-2:   #931823;
  --pen-ink: #fbf5ec;
  --pen-soft:#f0ddd8;   /* pen wash for selected rows */
  --tick:    #3f7d4e;   /* green pen: correct */
  --gold:    #b0801d;   /* amber: partial */
  --shadow-sm: 0 1px 2px rgba(38,34,26,.06);
  --shadow:  0 4px 16px rgba(38,34,26,.09);
  --shadow-lg: 0 24px 60px rgba(38,34,26,.20);
  --r: 5px;
  --r-lg: 12px;
  --serif: "Newsreader", Georgia, "Times New Roman", serif;
  --mono: "JetBrains Mono", ui-monospace, Menlo, monospace;
  --margin-w: 288px;
  /* one fine, uniform paper grain — subtle, consistent everywhere */
  --grain: url("data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='140'%20height='140'%3E%3Cfilter%20id='g'%3E%3CfeTurbulence%20type='fractalNoise'%20baseFrequency='0.8'%20numOctaves='2'%20stitchTiles='stitch'/%3E%3CfeColorMatrix%20type='saturate'%20values='0'/%3E%3C/filter%3E%3Crect%20width='100%25'%20height='100%25'%20filter='url(%23g)'%20opacity='0.35'/%3E%3C/svg%3E");
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper:   #14130e;   /* blackboard room */
    --sheet:   #1b190f;   /* the dark sheet */
    --sunk:    #232012;
    --ink:     #ece4cf;   /* warm chalk-white */
    --ink-2:   #b3aa90;
    --faint:   #786f58;
    --line:    #322e1f;
    --line-2:  #423c28;
    --pen:     #e65a4d;   /* red pen glows on black */
    --pen-2:   #f2705f;
    --pen-ink: #1a110d;
    --pen-soft:#2e1712;
    --tick:    #6cc07f;
    --gold:    #d4a63c;
    --shadow-sm: 0 1px 2px rgba(0,0,0,.4);
    --shadow:  0 4px 16px rgba(0,0,0,.45);
    --shadow-lg: 0 24px 60px rgba(0,0,0,.7);
  }
}
:root[data-theme="light"] {
  --paper:#ece4d3; --sheet:#f6f1e6; --sunk:#e4dcca; --ink:#26221a; --ink-2:#5c5443; --faint:#948a72;
  --line:#ddd3bd; --line-2:#cabfa4; --pen:#b4202e; --pen-2:#931823; --pen-ink:#fbf5ec; --pen-soft:#f0ddd8;
  --tick:#3f7d4e; --gold:#b0801d;
  --shadow-sm:0 1px 2px rgba(38,34,26,.06); --shadow:0 4px 16px rgba(38,34,26,.09); --shadow-lg:0 24px 60px rgba(38,34,26,.20);
}
:root[data-theme="dark"] {
  --paper:#14130e; --sheet:#1b190f; --sunk:#232012; --ink:#ece4cf; --ink-2:#b3aa90; --faint:#786f58;
  --line:#322e1f; --line-2:#423c28; --pen:#e65a4d; --pen-2:#f2705f; --pen-ink:#1a110d; --pen-soft:#2e1712;
  --tick:#6cc07f; --gold:#d4a63c;
  --shadow-sm:0 1px 2px rgba(0,0,0,.4); --shadow:0 4px 16px rgba(0,0,0,.45); --shadow-lg:0 24px 60px rgba(0,0,0,.7);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { height: 100%; }
body {
  margin: 0; font-family: var(--serif); color: var(--ink); background: var(--paper);
  font-size: 18px; line-height: 1.6; -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}
/* one uniform grain overlay for the whole app — fixed, subtle, consistent */
body::before {
  content: ""; position: fixed; inset: 0; z-index: 0; pointer-events: none;
  background-image: var(--grain); background-size: 140px 140px;
  opacity: .5; mix-blend-mode: soft-light;
}
.layout { display: flex; min-height: 100vh; position: relative; z-index: 1; }

h1, h2, h3 { margin: 0; font-weight: 600; font-family: var(--serif); text-wrap: balance; }
b, strong { font-weight: 600; }
.faint { color: var(--faint); }
.hidden { display: none !important; }
kbd { font-family: var(--mono); font-size: .68em; padding: .1em .4em; border: 1px solid var(--line-2); border-radius: 3px; background: var(--sunk); color: var(--ink-2); }
.ic { width: 20px; height: 20px; display: inline-block; flex: none; }
.ic-sm { width: 15px; height: 15px; }
.dot { width: 8px; height: 8px; border-radius: 50%; background: var(--faint); flex: none; }
.dot.on { background: var(--tick); } .dot.off { background: var(--pen); } .dot.warn { background: var(--gold); }

/* ---------- stamps (buttons) : rectangles, one radius ---------- */
.stamp {
  display: inline-flex; align-items: center; justify-content: center; gap: 7px;
  font-family: var(--mono); font-size: .72rem; font-weight: 600; text-transform: uppercase; letter-spacing: .08em;
  padding: 10px 15px; border-radius: var(--r); cursor: pointer;
  border: 1.5px solid var(--ink); background: transparent; color: var(--ink);
  transition: background .16s, color .16s, transform .06s, border-color .16s;
}
.stamp:hover { background: var(--ink); color: var(--paper); }
.stamp:active { transform: translateY(1px); }
.stamp-pen { border-color: var(--pen); color: var(--pen-ink); background: var(--pen); }
.stamp-pen:hover { background: var(--pen-2); border-color: var(--pen-2); color: var(--pen-ink); }
.stamp.ghost { border-color: var(--line-2); color: var(--ink-2); }
.stamp.ghost:hover { background: var(--sunk); color: var(--ink); border-color: var(--ink-2); }
.stamp.sm { padding: 6px 10px; font-size: .66rem; }
.stamp.full { width: 100%; }
.stamp:disabled { opacity: .4; cursor: not-allowed; }
.tag { font-family: var(--mono); font-size: .68rem; background: rgba(255,255,255,.22); padding: 0 6px; border-radius: 3px; }
.stamp:not(.stamp-pen) .tag { background: var(--sunk); }

.ibtn { display: inline-flex; align-items: center; justify-content: center; width: 34px; height: 34px; border-radius: var(--r); background: transparent; border: 1px solid transparent; color: var(--ink-2); cursor: pointer; transition: background .16s, color .16s; }
.ibtn:hover { background: var(--sunk); color: var(--ink); }
.ibtn.sm { width: 28px; height: 28px; }
.ibtn.floating { display: none; position: fixed; left: 16px; top: 16px; z-index: 45; background: var(--sheet); border-color: var(--line); box-shadow: var(--shadow); width: 40px; height: 40px; }

/* ---------- left margin: minimal ---------- */
.margin {
  width: var(--margin-w); flex: none; height: 100vh; position: sticky; top: 0; overflow-y: auto;
  border-right: 2px solid var(--pen); background: var(--paper); padding-bottom: 16px;
}
.margin-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; padding: 24px 20px 16px; }
.mast { display: flex; flex-direction: column; line-height: 1.05; min-width: 0; }
.mast-title { font-family: var(--serif); font-weight: 600; font-size: 1.45rem; letter-spacing: -.015em; }
.mast-sub { font-family: var(--mono); font-size: .58rem; text-transform: uppercase; letter-spacing: .28em; color: var(--pen); margin-top: 5px; }
.actions { display: flex; flex-direction: column; gap: 9px; padding: 0 20px 18px; }

.report-rule { font-family: var(--mono); font-size: .58rem; text-transform: uppercase; letter-spacing: .2em; color: var(--faint); padding-bottom: 7px; border-bottom: 1px solid var(--line); }
.sessions-rule { margin: 6px 20px 0; }
.session-list { list-style: none; margin: 8px 0 0; padding: 0 12px; }
.session-item { display: flex; align-items: center; justify-content: space-between; gap: 6px; padding: 9px 11px; border-radius: var(--r); cursor: pointer; border-left: 2px solid transparent; transition: background .14s; }
.session-item:hover { background: var(--sunk); }
.session-item.active { background: var(--pen-soft); border-left-color: var(--pen); }
.session-meta { display: flex; flex-direction: column; min-width: 0; }
.session-name { font-size: .95rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.session-date { font-family: var(--mono); font-size: .6rem; color: var(--faint); }
.btn-del { opacity: 0; }
.session-item:hover .btn-del { opacity: 1; }
.btn-del:hover { color: var(--pen); }
.margin-foot { display: flex; gap: 6px; padding: 18px 20px 0; }

/* ---------- desk + sheet : the focus ---------- */
.desk { flex: 1; min-width: 0; display: flex; justify-content: center; padding: 48px 32px 120px; }
.sheet-wrap { width: 100%; max-width: 680px; }
.sheet-top { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; margin-bottom: 26px; }
.sheet-top h1 { font-size: 1.5rem; font-weight: 600; letter-spacing: -.01em; }
.sheet-top p { margin: 4px 0 0; font-family: var(--mono); font-size: .68rem; }
.progress-track { flex: 1; max-width: 160px; height: 2px; background: var(--line); overflow: hidden; }
.progress-fill { height: 100%; width: 0; background: var(--pen); transition: width .35s ease; }
.screen.hidden { display: none; }

/* question sheet — clean, no internal ruling */
.q-card { background: var(--sheet); border: 1px solid var(--line); border-left: 3px solid var(--pen); border-radius: var(--r-lg); box-shadow: var(--shadow); padding: 38px 44px; position: relative; }
@media (prefers-reduced-motion: reduce) { * { animation: none !important; transition: none !important; } }

.q-head { display: flex; align-items: center; gap: 10px; margin-bottom: 22px; }
.q-badge { font-family: var(--mono); font-size: .6rem; text-transform: uppercase; letter-spacing: .14em; color: var(--pen); }
.unclear-btn {
  margin-left: auto; display: inline-flex; align-items: center; gap: 6px;
  font-family: var(--mono); font-size: .62rem; text-transform: uppercase; letter-spacing: .08em;
  color: var(--ink-2); background: transparent; border: 1px solid var(--line-2); border-radius: 999px;
  padding: 5px 12px; cursor: pointer; transition: all .15s;
}
.unclear-btn:hover { color: var(--pen); border-color: var(--pen); background: var(--pen-soft); }
.unclear-btn .ic { width: 13px; height: 13px; }
.q-title { font-size: 1.5rem; line-height: 1.42; font-weight: 500; letter-spacing: -.005em; }

.options { display: flex; flex-direction: column; margin-top: 26px; }
.opt { display: block; padding: 15px 6px; cursor: pointer; border-top: 1px solid var(--line); transition: background .12s; }
.opt:first-child { border-top: none; }
.opt:hover { background: rgba(0,0,0,.025); }
.opt.disabled { cursor: default; }
.opt.disabled:hover { background: transparent; }
.opt-row { display: flex; align-items: flex-start; gap: 15px; }
/* option keys are deliberate circles — a bubble-sheet motif */
.opt-key { font-family: var(--mono); font-size: .82rem; font-weight: 600; width: 28px; height: 28px; flex: none; border: 1.5px solid var(--line-2); border-radius: 50%; color: var(--ink-2); display: inline-flex; align-items: center; justify-content: center; margin-top: 1px; transition: all .16s; }
.opt-text { flex: 1; padding-top: 3px; font-size: 1.08rem; }
.opt input { position: absolute; opacity: 0; pointer-events: none; }
.opt.correct .opt-key { border-color: var(--tick); background: var(--tick); color: #fff; }
.opt.wrong .opt-key { border-color: var(--pen); background: var(--pen); color: #fff; }
.opt.wrong .opt-text { text-decoration: line-through; text-decoration-color: var(--pen); color: var(--ink-2); }

/* explanation as a handwritten margin note */
.exp { margin: 10px 0 2px 43px; font-size: 1rem; line-height: 1.5; font-style: italic; padding-left: 14px; border-left: 2px solid var(--line-2); color: var(--ink-2); }
.exp.ok { border-left-color: var(--tick); }
.exp.no { border-left-color: var(--pen); }
.exp-tag { font-family: var(--mono); font-style: normal; font-size: .56rem; text-transform: uppercase; letter-spacing: .1em; margin-right: 8px; }
.exp.ok .exp-tag { color: var(--tick); }
.exp.no .exp-tag { color: var(--pen); }

.fib-input { width: 100%; padding: 10px 4px; margin-top: 24px; font-family: var(--serif); font-size: 1.18rem; border: none; border-bottom: 2px solid var(--ink-2); background: transparent; color: var(--ink); }
.fib-input:focus { outline: none; border-bottom-color: var(--pen); }

/* grade rubric */
.grade { margin-top: 30px; padding-top: 22px; border-top: 1px dashed var(--line-2); }
.grade-q { font-family: var(--mono); font-size: .64rem; text-transform: uppercase; letter-spacing: .08em; color: var(--faint); margin-bottom: 14px; }
.grade-btns { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.grade-btn { display: flex; flex-direction: column; align-items: center; gap: 3px; padding: 11px 4px; cursor: pointer; border: 1.5px solid var(--line-2); border-radius: var(--r); background: var(--sheet); color: var(--ink); font-family: var(--mono); font-weight: 600; font-size: .72rem; text-transform: uppercase; letter-spacing: .04em; transition: border-color .14s, transform .1s, box-shadow .14s; }
.grade-btn:hover { transform: translateY(-1px); box-shadow: var(--shadow-sm); }
.grade-btn .when { font-size: .6rem; font-weight: 500; letter-spacing: 0; text-transform: none; color: var(--faint); }
.grade-btn[data-g="1"]:hover { border-color: var(--pen); color: var(--pen); }
.grade-btn[data-g="2"]:hover { border-color: var(--gold); }
.grade-btn[data-g="3"]:hover { border-color: var(--ink); }
.grade-btn[data-g="4"]:hover { border-color: var(--tick); color: var(--tick); }
.grade-done { font-family: var(--mono); font-size: .72rem; color: var(--faint); }
.grade-done b { color: var(--ink); }
/* the grade you picked (persists on revisit; click another to change it) */
.grade-btn.chosen { border-color: var(--pen); background: var(--pen-soft); box-shadow: inset 0 0 0 1px var(--pen); }
.grade-btn.chosen .when { color: var(--pen-2); }

.nav-row { display: flex; align-items: center; justify-content: space-between; gap: 14px; margin-top: 22px; }
.kbd-hint { font-family: var(--mono); font-size: .62rem; color: var(--faint); text-align: center; }
.submit-row { margin-top: 18px; display: flex; justify-content: center; }

/* score */
.grade-sheet { background: var(--sheet); border: 1px solid var(--line); border-left: 3px solid var(--pen); border-radius: var(--r-lg); box-shadow: var(--shadow); padding: 50px; text-align: center; }
.grade-stamp { display: inline-block; font-family: var(--mono); font-size: 2.6rem; font-weight: 600; color: var(--pen); border: 3px solid var(--pen); border-radius: 8px; padding: 8px 26px; transform: rotate(-4deg); font-variant-numeric: tabular-nums; }
#score-feedback { margin: 24px 0 0; font-size: 1.12rem; }
.score-actions { display: flex; gap: 12px; justify-content: center; margin-top: 26px; flex-wrap: wrap; }
.score-breakdown { margin-top: 34px; display: flex; flex-direction: column; gap: 13px; text-align: left; }
.sb-row { display: grid; grid-template-columns: 1fr auto; gap: 4px 10px; align-items: center; }
.sb-name { font-size: .96rem; }
.sb-val { font-family: var(--mono); font-size: .7rem; color: var(--faint); }
.sb-bar { grid-column: 1/-1; height: 3px; background: var(--line); overflow: hidden; }
.sb-fill { height: 100%; }

/* ---------- slide-in panels ---------- */
.panel { position: fixed; top: 0; right: 0; height: 100vh; width: 400px; max-width: 92vw; border-left: 3px solid var(--pen); box-shadow: var(--shadow-lg); z-index: 60; transform: translateX(100%); transition: transform .3s cubic-bezier(.4,0,.2,1); display: flex; flex-direction: column; background: var(--sheet); }
.panel.open { transform: none; }
.panel-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 18px 22px; border-bottom: 1px solid var(--line); }
.panel-head h2 { font-size: 1.15rem; display: flex; align-items: center; gap: 8px; }
.panel-body { padding: 24px 22px; overflow-y: auto; flex: 1; }
.panel-body h3 { font-size: 1.15rem; margin: 0 0 12px; color: var(--pen); }
.panel-body ul { padding-left: 20px; margin: 10px 0; }
.panel-body li { margin: 8px 0; font-size: 1.02rem; }
.panel-body strong { font-weight: 600; }

/* stats (in settings panel) */
.stat-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 8px; }
.stat { display: flex; align-items: baseline; gap: 6px; padding: 10px 12px; background: var(--sunk); border-radius: var(--r); }
.stat-num { font-family: var(--mono); font-size: 1.2rem; font-weight: 600; font-variant-numeric: tabular-nums; }
.stat-lbl { font-family: var(--mono); font-size: .58rem; text-transform: uppercase; letter-spacing: .1em; color: var(--faint); }
#s-due { color: var(--pen); }
.streak-row { display: flex; align-items: center; justify-content: space-between; font-family: var(--mono); font-size: .8rem; color: var(--ink-2); margin-top: 4px; }
#forecast { width: 100%; display: block; }
.mastery { display: flex; flex-direction: column; gap: 10px; }
.mastery-row { display: grid; grid-template-columns: 1fr auto; gap: 4px 8px; align-items: center; }
.mastery-name { font-size: .9rem; color: var(--ink-2); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mastery-pct { font-family: var(--mono); font-size: .68rem; color: var(--faint); }
.mastery-bar { grid-column: 1/-1; height: 3px; background: var(--line); overflow: hidden; }
.mastery-fill { height: 100%; background: var(--pen); transition: width .5s ease; }

/* settings block */
.set-block { margin-bottom: 34px; display: flex; flex-direction: column; gap: 13px; }
.set-block h3 { font-size: 1.08rem; }
.set-note { font-size: .86rem; margin: 0; line-height: 1.5; }
.set-field { display: flex; flex-direction: column; gap: 6px; font-family: var(--mono); font-size: .58rem; text-transform: uppercase; letter-spacing: .08em; color: var(--faint); }
.set-field input { font-family: var(--mono); font-size: .8rem; text-transform: none; letter-spacing: 0; padding: 11px 13px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--sunk); color: var(--ink); }
.set-field input:focus { outline: none; border-color: var(--pen); }
.set-actions { display: flex; gap: 8px; }
.cfg-status { font-family: var(--mono); font-size: .66rem; margin: 0; white-space: pre-wrap; }

/* ---------- floating tutor ---------- */
.fab { position: fixed; right: 26px; bottom: 26px; z-index: 65; width: 52px; height: 52px; border-radius: 50%; background: var(--pen); color: var(--pen-ink); border: none; cursor: pointer; box-shadow: var(--shadow-lg); display: flex; align-items: center; justify-content: center; transition: transform .18s, background .18s; }
.fab:hover { background: var(--pen-2); transform: translateY(-2px) rotate(-6deg); }
.fab .ic { width: 23px; height: 23px; }

.dock { position: fixed; right: 26px; bottom: 26px; z-index: 66; width: 356px; max-width: calc(100vw - 32px); height: 480px; max-height: calc(100vh - 52px); border: 1px solid var(--line); border-top: 3px solid var(--pen); border-radius: var(--r-lg); box-shadow: var(--shadow-lg); display: flex; flex-direction: column; overflow: hidden; background: var(--sheet); }
.dock.hidden { display: none; }
.dock-head { display: flex; align-items: center; justify-content: space-between; gap: 8px; padding: 11px 13px; border-bottom: 1px solid var(--line); }
.dock-title { display: flex; align-items: center; gap: 7px; font-family: var(--mono); font-size: .7rem; text-transform: uppercase; letter-spacing: .1em; color: var(--ink); }
.dock-tools { display: flex; align-items: center; gap: 4px; }
.dock-model { font-family: var(--mono); font-size: .62rem; max-width: 116px; padding: 4px 6px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--sunk); color: var(--ink); }
.dock-model:focus { outline: none; border-color: var(--pen); }

.dock-log { flex: 1; overflow-y: auto; padding: 15px; display: flex; flex-direction: column; gap: 11px; }
.msg { max-width: 90%; padding: 10px 13px; border-radius: var(--r-lg); font-size: .95rem; line-height: 1.5; white-space: pre-wrap; word-wrap: break-word; }
.msg.user { align-self: flex-end; background: var(--pen); color: var(--pen-ink); border-bottom-right-radius: 3px; }
.msg.ai { align-self: flex-start; background: var(--sunk); color: var(--ink); border-bottom-left-radius: 3px; }
.msg.ai code { font-family: var(--mono); font-size: .82em; background: var(--sheet); padding: 1px 5px; border-radius: 3px; }
.msg.ai pre { background: var(--sheet); border: 1px solid var(--line); padding: 10px; border-radius: var(--r); overflow-x: auto; }
.msg.ai pre code { background: none; padding: 0; }
.msg.sys { align-self: center; text-align: center; font-family: var(--mono); font-size: .66rem; color: var(--faint); background: transparent; max-width: 100%; }
.msg .cursor { display: inline-block; width: 6px; height: 1em; background: var(--pen); vertical-align: text-bottom; animation: blink 1s steps(2) infinite; }
@keyframes blink { 50% { opacity: 0; } }
.dock-unavail { padding: 24px; text-align: center; color: var(--faint); font-family: var(--mono); font-size: .72rem; line-height: 1.7; }
.dock-unavail code { background: var(--sunk); padding: 1px 5px; border-radius: 3px; }

.dock-input { display: flex; gap: 6px; align-items: flex-end; padding: 11px 13px; border-top: 1px solid var(--line); }
.dock-input textarea { flex: 1; resize: none; font-family: var(--serif); font-size: 1rem; line-height: 1.4; padding: 9px 11px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--sunk); color: var(--ink); max-height: 120px; }
.dock-input textarea:focus { outline: none; border-color: var(--pen); }
.dock-input textarea:disabled { opacity: .5; }
#chat-send { color: var(--pen); }
#chat-send:hover { background: var(--pen-soft); }

/* ---------- modal ---------- */
.modal { position: fixed; inset: 0; z-index: 80; display: flex; align-items: center; justify-content: center; background: rgba(20,18,12,.55); padding: 20px; }
.modal.hidden { display: none; }
.modal-card { width: 100%; max-width: 420px; border: 1px solid var(--line); border-top: 3px solid var(--pen); border-radius: var(--r-lg); box-shadow: var(--shadow-lg); background: var(--sheet); }
.modal-body { padding: 22px; display: flex; flex-direction: column; gap: 16px; }
.field { display: flex; flex-direction: column; gap: 6px; font-family: var(--mono); font-size: .62rem; text-transform: uppercase; letter-spacing: .06em; color: var(--ink-2); }
.field select, .field input { font-family: var(--serif); font-size: 1rem; text-transform: none; letter-spacing: 0; padding: 11px 13px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--sunk); color: var(--ink); }
.field select:focus, .field input:focus { outline: none; border-color: var(--pen); }

.scrim { position: fixed; inset: 0; background: rgba(20,18,12,.4); z-index: 55; }
.scrim[hidden] { display: none; }

.toast { position: fixed; bottom: 26px; left: 50%; transform: translateX(-50%); background: var(--ink); color: var(--paper); font-family: var(--mono); font-size: .76rem; padding: 11px 18px; border-radius: var(--r); z-index: 100; box-shadow: var(--shadow-lg); }
.toast.hidden { display: none; }

:focus-visible { outline: 2px solid var(--pen); outline-offset: 2px; }

/* ---------- responsive ---------- */
body.margin-collapsed .margin { display: none; }
body.margin-collapsed #btn-open-margin { display: inline-flex; }
@media (max-width: 900px) {
  .margin { position: fixed; z-index: 70; box-shadow: var(--shadow-lg); }
  body:not(.margin-open) .margin { display: none; }
  body:not(.margin-open) #btn-open-margin { display: inline-flex; }
  .desk { padding-top: 70px; }
}
@media (max-width: 560px) {
  .q-card { padding: 26px 22px; }
  .q-title { font-size: 1.3rem; }
  .grade-btns { grid-template-columns: repeat(2, 1fr); }
  .dock { right: 0; bottom: 0; width: 100vw; height: 74vh; border-radius: var(--r-lg) var(--r-lg) 0 0; }
  .fab { right: 18px; bottom: 18px; }
}

/* ---- theory (spaced-repetition) toggle on each question ---- */
.theory-toggle {
  display: inline-flex; align-items: center; gap: 5px;
  font-family: var(--mono); font-size: .58rem; text-transform: uppercase; letter-spacing: .08em;
  color: var(--ink-2); background: transparent; border: 1px dashed var(--line-2); border-radius: 999px;
  padding: 4px 10px; cursor: pointer; transition: all .15s;
}
.theory-toggle .ic { width: 12px; height: 12px; }
.theory-toggle:hover { color: var(--ink); border-color: var(--ink-2); }
.theory-toggle.on { color: var(--pen); border-style: solid; border-color: var(--pen); background: var(--pen-soft); }

/* ---- draft-paper button badge ---- */
#btn-paper { position: relative; }
#btn-paper .badge {
  position: absolute; top: -3px; right: -3px; min-width: 15px; height: 15px; padding: 0 4px;
  font-family: var(--mono); font-size: .58rem; line-height: 15px; text-align: center;
  color: var(--pen-ink); background: var(--pen); border-radius: 999px;
}
.badge.hidden { display: none; }

/* ---- draft-paper panel textarea ---- */
.paper-text {
  width: 100%; min-height: 46vh; resize: vertical; margin-top: 6px;
  font-family: var(--mono); font-size: .82rem; line-height: 1.6; color: var(--ink);
  background: var(--sunk); border: 1px solid var(--line-2); border-radius: var(--r);
  padding: 12px 14px; box-sizing: border-box;
}
.paper-text:focus { outline: none; border-color: var(--pen); }

/* ---- chat: attached-image preview + images inside messages ---- */
.dock-imgchip { display: flex; align-items: center; gap: 8px; padding: 8px 12px 0; }
.dock-imgchip.hidden { display: none; }
.dock-imgchip img { height: 42px; width: auto; border-radius: 6px; border: 1px solid var(--line-2); }
.dock-imgchip .img-x {
  width: 22px; height: 22px; border-radius: 999px; border: 1px solid var(--line-2);
  background: var(--sunk); color: var(--ink-2); cursor: pointer; font-size: 15px; line-height: 1;
}
.dock-imgchip .img-x:hover { color: var(--pen); border-color: var(--pen); }
.msg-img { display: block; max-width: 100%; margin-top: 8px; border-radius: 8px; border: 1px solid var(--line-2); }

/* ---- MathJax in chat: keep wide display math scrollable, not overflowing the dock ---- */
.msg mjx-container { max-width: 100%; }
.msg mjx-container[display="true"] { overflow-x: auto; overflow-y: hidden; padding: 2px 0; }