/* Layout concept: an engineering drawing sheet. Cool drafting-paper ground with a faint
   5 mm grid, white sheets with hairline borders, technical blue for actions, safety amber
   for marks and progress, condensed signage type for headings, title-block style labels. */
:root {
  --bg: #eef2f5;
  --surface: #ffffff;
  --surface-2: #e8eef3;
  --ink: #14212d;
  --muted: #4f5f6d;
  --line: #cfd9e2;
  --grid: rgba(29, 86, 140, .07);
  --accent: #1d5a8e;
  --accent-ink: #ffffff;
  --accent-soft: #dde9f4;
  --amber: #a86a00;
  --amber-soft: #fbedcf;
  --red: #b3352a;
  --red-soft: #f8e1dd;
  --good: #217346;
  --good-soft: #dcf0e3;
  --plate: #ffffff;
  --shadow: 0 1px 2px rgba(20, 33, 45, .06), 0 4px 14px rgba(20, 33, 45, .05);
  --font-display: "Barlow Condensed", "Arial Narrow", "Segoe UI", system-ui, sans-serif;
  --font-body: "Atkinson Hyperlegible", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --radius: 6px;
  --radius-sm: 4px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f161d; --surface: #16212b; --surface-2: #1d2a36; --ink: #e5ecf2; --muted: #9fb0bf;
    --line: #2c3b49; --grid: rgba(120, 170, 220, .06); --accent: #7fb6e8; --accent-ink: #0c1620; --accent-soft: #1d3247;
    --amber: #f2b54a; --amber-soft: #3a2d14; --red: #f08a7c; --red-soft: #3c211d;
    --good: #7ccf9c; --good-soft: #1a3325; --plate: #f4f6f8; --shadow: 0 1px 2px rgba(0,0,0,.4);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0f161d; --surface: #16212b; --surface-2: #1d2a36; --ink: #e5ecf2; --muted: #9fb0bf;
  --line: #2c3b49; --grid: rgba(120, 170, 220, .06); --accent: #7fb6e8; --accent-ink: #0c1620; --accent-soft: #1d3247;
  --amber: #f2b54a; --amber-soft: #3a2d14; --red: #f08a7c; --red-soft: #3c211d;
  --good: #7ccf9c; --good-soft: #1a3325; --plate: #f4f6f8; --shadow: 0 1px 2px rgba(0,0,0,.4);
  color-scheme: dark;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: var(--font-body); font-size: 1.0625rem; line-height: 1.6;
}
img { max-width: 100%; }
[hidden] { display: none !important; }
a { color: var(--accent); text-underline-offset: 3px; }
h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.15; text-wrap: balance; margin: 0; letter-spacing: -0.01em; }
h1 { font-size: clamp(2rem, 5vw, 3.1rem); font-weight: 700; }
h2 { font-size: clamp(1.45rem, 3vw, 1.9rem); font-weight: 650; }
h3 { font-size: 1.2rem; font-weight: 650; }
p { margin: 0; }
:focus-visible { outline: 3px solid var(--amber); outline-offset: 2px; border-radius: 4px; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--accent); color: var(--accent-ink); padding: 8px 14px; border-radius: 8px; z-index: 50; }
.skip:focus { left: 16px; }
.eyebrow { font-family: var(--font-mono); font-size: .78rem; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.muted { color: var(--muted); }
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

/* ---------- Header ---------- */
body::before { content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px); z-index: 10; background: var(--surface); }
.topbar {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 20;
  background: var(--surface); border-bottom: 1px solid var(--line);
}
.topbar-inner, .wrap {
  max-width: 1120px; margin: 0 auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.topbar-inner { display: flex; align-items: center; gap: 16px; padding-block: 10px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); font-family: var(--font-display); font-weight: 700; font-size: 1.05rem; line-height: 1.1; }
.brand-mark { width: 34px; height: 34px; border-radius: 9px; background: var(--accent); color: var(--accent-ink); display: grid; place-items: center; flex: none; }
.brand small { display: block; font-family: var(--font-body); font-weight: 400; font-size: .75rem; color: var(--muted); }
.nav { display: flex; gap: 4px; flex-wrap: wrap; margin-left: auto; }
.nav a { text-decoration: none; color: var(--muted); padding: 7px 11px; border-radius: 8px; font-size: .95rem; }
.nav a:hover { background: var(--surface-2); color: var(--ink); }
.nav a[aria-current="page"] { background: var(--accent-soft); color: var(--accent); font-weight: 700; }
.btn.menu-btn { display: none; margin-left: auto; }
@media (max-width: 820px) {
  .btn.menu-btn { display: inline-flex; }
  .nav { display: none; width: 100%; flex-direction: column; margin: 0; }
  .nav.open { display: flex; }
  .nav a { padding: 11px 12px; }
}

main { padding-block: 28px 64px; }
.wrap { display: grid; gap: 28px; }
.section-head { display: grid; gap: 6px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font: inherit; font-weight: 700; font-size: 1rem; cursor: pointer;
  padding: 10px 18px; border-radius: 10px; border: 1.5px solid var(--accent);
  background: var(--accent); color: var(--accent-ink); text-decoration: none; min-height: 44px;
  transition: transform .12s ease, background .12s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: none; }
.btn.secondary { background: transparent; color: var(--accent); }
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn.danger { background: var(--red); border-color: var(--red); color: #fff; }
.btn.small { padding: 6px 12px; min-height: 36px; font-size: .92rem; }
.btn[disabled] { opacity: .5; cursor: not-allowed; transform: none; }
.btn-row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }

/* ---------- Cards / grid ---------- */
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; box-shadow: var(--shadow); min-width: 0; }
.grid { display: grid; gap: 16px; }
.grid.cols-3 { grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr)); }
.grid.cols-2 { grid-template-columns: repeat(auto-fill, minmax(min(100%, 360px), 1fr)); }
.grid.cols-4 { grid-template-columns: repeat(auto-fill, minmax(min(100%, 200px), 1fr)); }

/* ---------- Hero ---------- */
.hero { display: grid; gap: 18px; padding-block: 8px 4px; }
.hero p.lede { font-size: 1.2rem; color: var(--muted); max-width: 60ch; }
.hero .meta { display: flex; gap: 10px; flex-wrap: wrap; }
.chip { display: inline-flex; align-items: center; gap: 6px; padding: 5px 12px; border-radius: 999px; background: var(--surface); border: 1px solid var(--line); font-size: .9rem; }
.chip strong { font-family: var(--font-mono); font-weight: 600; }

/* ---------- Dashboard tiles ---------- */
.tile { display: grid; grid-template-columns: auto 1fr; gap: 6px 14px; align-items: start; text-decoration: none; color: var(--ink); }
.tile:hover { border-color: var(--accent); }
.tile .ico { grid-row: span 2; width: 46px; height: 46px; border-radius: 12px; background: var(--accent-soft); color: var(--accent); display: grid; place-items: center; }
.tile h3 { align-self: end; }
.tile p { color: var(--muted); font-size: .97rem; }

.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 160px), 1fr)); gap: 14px; }
.stat { display: grid; gap: 2px; }
.stat .num { font-family: var(--font-display); font-size: 2rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.stat .lbl { color: var(--muted); font-size: .92rem; }
.bar { height: 10px; border-radius: 999px; background: var(--surface-2); overflow: hidden; border: 1px solid var(--line); }
.bar > span { display: block; height: 100%; background: var(--amber); border-radius: inherit; transition: width .5s ease; }
.progress-row { display: grid; gap: 8px; }
.progress-row .top { display: flex; justify-content: space-between; gap: 12px; font-weight: 700; }

.steps { counter-reset: s; display: grid; gap: 12px; padding: 0; margin: 0; list-style: none; }
.steps li { counter-increment: s; display: grid; grid-template-columns: 34px 1fr; gap: 12px; align-items: start; }
.steps li::before { content: counter(s); font-family: var(--font-mono); font-weight: 600; width: 30px; height: 30px; border-radius: 50%; border: 1.5px solid var(--accent); color: var(--accent); display: grid; place-items: center; font-size: .9rem; }

/* ---------- Topic cards ---------- */
.topic-card { display: grid; gap: 10px; text-decoration: none; color: var(--ink); align-content: start; }
.topic-card:hover { border-color: var(--accent); }
.topic-card .row { display: flex; align-items: center; gap: 12px; }
.topic-card .ico { width: 42px; height: 42px; border-radius: 11px; background: var(--amber-soft); color: var(--amber); display: grid; place-items: center; flex: none; }
.topic-card p { color: var(--muted); font-size: .96rem; }
.topic-card .foot { display: flex; justify-content: space-between; align-items: center; font-size: .88rem; color: var(--muted); border-top: 1px dashed var(--line); padding-top: 10px; margin-top: auto; }
.badge { display: inline-flex; align-items: center; gap: 4px; font-size: .8rem; font-weight: 700; padding: 2px 9px; border-radius: 999px; }
.badge.done { background: var(--good-soft); color: var(--good); }
.badge.todo { background: var(--surface-2); color: var(--muted); }

/* ---------- Topic page ---------- */
.topic-layout { display: grid; gap: 22px; grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr); align-items: start; }
@media (max-width: 900px) { .topic-layout { grid-template-columns: minmax(0, 1fr); } }
.knowledge { margin: 0; padding-left: 1.2em; display: grid; gap: 10px; max-width: 68ch; }
.knowledge li::marker { color: var(--accent); }
.terms { display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 220px), 1fr)); }
.term { background: var(--surface-2); border-radius: var(--radius-sm); padding: 12px 14px; display: grid; gap: 4px; }
.term dt { font-family: var(--font-display); font-weight: 700; }
.term dd { margin: 0; font-size: .95rem; color: var(--muted); }
.remember { display: flex; flex-wrap: wrap; gap: 8px; }
.remember span { background: var(--amber-soft); color: var(--ink); border: 1px solid color-mix(in srgb, var(--amber) 35%, transparent); padding: 6px 12px; border-radius: 8px; font-weight: 700; font-size: .95rem; }
.label-head { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; }
.label-head .eyebrow { color: var(--accent); font-weight: 600; }
.pager { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }

/* ---------- Questions ---------- */
.qgroup { display: grid; gap: 16px; }
.qgroup-head { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.part { display: grid; gap: 14px; }
.part-head { display: flex; justify-content: space-between; gap: 12px; align-items: start; }
.part-num { font-family: var(--font-mono); font-weight: 600; color: var(--accent); }
.marks { flex: none; font-family: var(--font-mono); font-size: .85rem; font-weight: 600; background: var(--amber-soft); color: var(--ink); padding: 3px 10px; border-radius: 999px; white-space: nowrap; }
.stem { color: var(--muted); font-style: italic; }
.qtext { font-weight: 700; font-size: 1.08rem; max-width: 70ch; }
.cmd { font-size: .8rem; font-family: var(--font-mono); color: var(--muted); }
.cmd a { color: inherit; }
.guidance { background: var(--accent-soft); border-radius: var(--radius-sm); padding: 10px 14px; font-size: .95rem; }
.answer-lines { display: grid; gap: 8px; }
.answer-line { display: grid; grid-template-columns: 48px 1fr; gap: 8px; align-items: center; }
.answer-line label { font-family: var(--font-mono); color: var(--muted); font-size: .95rem; }
input[type="text"], textarea {
  font: inherit; color: var(--ink); background: var(--surface); width: 100%;
  border: 1.5px solid var(--line); border-radius: var(--radius-sm); padding: 10px 12px; min-height: 44px;
}
textarea { min-height: 180px; resize: vertical; line-height: 1.55; }
input[type="text"]:focus, textarea:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-soft); }
.wordcount { font-size: .82rem; color: var(--muted); text-align: right; font-family: var(--font-mono); }


.table-scroll { overflow-x: auto; }

/* ---------- Feedback ---------- */
.feedback { display: grid; gap: 12px; border-top: 1px dashed var(--line); padding-top: 14px; }
.score-pill { display: inline-flex; align-items: baseline; gap: 6px; font-family: var(--font-display); font-weight: 700; font-size: 1.3rem; }
.score-pill small { font-family: var(--font-body); font-weight: 400; font-size: .85rem; color: var(--muted); }
.points { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.points li { display: grid; grid-template-columns: 22px 1fr; gap: 8px; align-items: start; font-size: .96rem; }
.points li .mk { width: 20px; height: 20px; border-radius: 50%; display: grid; place-items: center; font-size: .75rem; font-weight: 700; margin-top: 3px; }
.points li.hit .mk { background: var(--good); color: var(--surface); }
.points li.miss .mk { background: var(--surface-2); color: var(--muted); border: 1.5px solid var(--line); }
.points li.miss { color: var(--muted); }
.model { background: var(--surface-2); border-radius: var(--radius-sm); padding: 14px 16px; display: grid; gap: 8px; }
.model p { white-space: pre-line; }
.note { font-size: .85rem; color: var(--muted); }

/* ---------- Tabs ---------- */
.tabs { display: flex; gap: 6px; flex-wrap: wrap; }
.tabs button { font: inherit; cursor: pointer; border: 1.5px solid var(--line); background: var(--surface); color: var(--ink); padding: 7px 13px; border-radius: 999px; font-weight: 700; font-size: .92rem; min-height: 40px; }
.tabs button[aria-selected="true"] { background: var(--ink); color: var(--bg); border-color: var(--ink); }

/* ---------- Quiz ---------- */
.quiz-card { max-width: 760px; width: 100%; display: grid; gap: 18px; }
.quiz-opts { display: grid; gap: 10px; }
.quiz-opts button { font: inherit; text-align: left; cursor: pointer; padding: 13px 16px; border-radius: 10px; border: 1.5px solid var(--line); background: var(--surface); color: var(--ink); display: grid; grid-template-columns: 28px 1fr; gap: 10px; align-items: center; min-height: 48px; }
.quiz-opts button:hover:not([disabled]) { border-color: var(--accent); }
.quiz-opts button b { font-family: var(--font-mono); color: var(--muted); }
.quiz-opts button.right { border-color: var(--good); background: var(--good-soft); }
.quiz-opts button.wrong { border-color: var(--red); background: var(--red-soft); }
.quiz-opts button[disabled] { cursor: default; }
.quiz-top { display: flex; justify-content: space-between; gap: 12px; align-items: center; flex-wrap: wrap; }
.fb { padding: 12px 14px; border-radius: var(--radius-sm); }
.fb.right { background: var(--good-soft); }
.fb.wrong { background: var(--red-soft); }
.choice-row { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 160px), 1fr)); }
.choice { text-align: left; font: inherit; cursor: pointer; border: 1.5px solid var(--line); background: var(--surface); color: var(--ink); border-radius: var(--radius); padding: 18px; display: grid; gap: 4px; }
.choice:hover { border-color: var(--accent); }
.choice .big { font-family: var(--font-display); font-size: 2rem; font-weight: 700; }

/* ---------- Paper mode ---------- */
.paper-bar { position: sticky; top: calc(env(safe-area-inset-top, 0px) + var(--topbar-h, 60px)); z-index: 15; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 16px; display: grid; gap: 10px; box-shadow: var(--shadow); }
.paper-bar .row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; justify-content: space-between; }
.timer { font-family: var(--font-mono); font-size: 1.6rem; font-weight: 600; font-variant-numeric: tabular-nums; }
.timer.low { color: var(--red); }
.qnav { display: flex; gap: 6px; flex-wrap: wrap; }
.qnav button { font: inherit; font-family: var(--font-mono); font-weight: 600; cursor: pointer; width: 44px; height: 44px; border-radius: 10px; border: 1.5px solid var(--line); background: var(--surface); color: var(--ink); position: relative; }
.qnav button.complete { background: var(--good-soft); border-color: var(--good); }
.qnav button.partial { background: var(--amber-soft); border-color: var(--amber); }
.qnav button[aria-current="true"] { outline: 3px solid var(--ink); outline-offset: 1px; }
.legend { display: flex; gap: 14px; flex-wrap: wrap; font-size: .82rem; color: var(--muted); }
.legend i { display: inline-block; width: 12px; height: 12px; border-radius: 3px; border: 1.5px solid var(--line); vertical-align: -1px; margin-right: 4px; }
.legend i.c { background: var(--good-soft); border-color: var(--good); }
.legend i.p { background: var(--amber-soft); border-color: var(--amber); }
.paper-table { width: 100%; border-collapse: collapse; font-variant-numeric: tabular-nums; }
.paper-table th, .paper-table td { padding: 8px 10px; border-bottom: 1px solid var(--line); text-align: left; }
.paper-table td:last-child, .paper-table th:last-child { text-align: right; font-family: var(--font-mono); }
.paper-table tfoot td { font-weight: 700; border-bottom: 0; }

.confirm { border: 2px solid var(--red); background: var(--red-soft); border-radius: var(--radius); padding: 16px; display: grid; gap: 12px; }
.review-part { display: grid; gap: 10px; padding-block: 14px; border-top: 1px solid var(--line); }
.your-answer { background: var(--surface-2); border-radius: var(--radius-sm); padding: 10px 14px; white-space: pre-line; font-size: .96rem; }

.cmd-list { display: grid; gap: 12px; }
.cmd-item { display: grid; grid-template-columns: 130px 1fr; gap: 16px; align-items: start; }
.cmd-item h3 { font-family: var(--font-mono); font-size: 1rem; letter-spacing: .06em; text-transform: uppercase; color: var(--accent); padding-top: 2px; }
.cmd-item .ex { font-size: .95rem; color: var(--muted); margin-top: 4px; }
@media (max-width: 560px) { .cmd-item { grid-template-columns: 1fr; gap: 4px; } }

.footer { border-top: 1px solid var(--line); padding-block: 22px; font-size: .88rem; color: var(--muted); }
.footer .wrap { gap: 6px; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}
.fade-in { animation: fade .25s ease both; }
@keyframes fade { from { opacity: .4; transform: translateY(4px); } to { opacity: 1; transform: none; } }


/* ---------- Engineering additions ---------- */
body { background-color: var(--bg); background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px); background-size: 20px 20px; }
h1 { font-size: clamp(2.2rem, 5.4vw, 3.4rem); font-weight: 700; letter-spacing: 0; }
h2 { font-weight: 700; letter-spacing: 0; }
h3 { font-weight: 700; font-size: 1.3rem; letter-spacing: 0; }
.brand { font-size: 1.25rem; letter-spacing: .01em; }
.brand-mark { border-radius: 4px; }
.btn { border-radius: var(--radius); }
.btn.danger { color: var(--accent-ink); }
.of { color: var(--muted); font-size: 1rem; }
.hero { padding-block: 12px 6px; }
.hero .eyebrow { color: var(--accent); font-weight: 600; }
.tile .ico, .topic-card .ico { border-radius: var(--radius); }
.topic-card .ico { background: var(--accent-soft); color: var(--accent); }
.topic-card .spec { font-family: var(--font-mono); font-size: .74rem; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); display: block; }
.topic-card h3 { font-size: 1.25rem; }
.paper-sub { font-family: var(--font-display); font-size: 1.3rem; }
.tabs button { border-radius: var(--radius); }
.tabs button[aria-pressed="true"] { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.qtabs button { font-family: var(--font-mono); font-weight: 600; min-width: 64px; }
.qtabs small { font-weight: 400; opacity: .75; font-size: .78rem; }
.paper-pick .note a { color: inherit; }

/* question card: title-block style header */
.qgroup-head .eyebrow { color: var(--accent); font-weight: 600; }
.qgroup-head p { margin-top: 2px; }
.marks.big { font-size: .95rem; padding: 5px 12px; }
.marks { border-radius: var(--radius-sm); background: var(--amber-soft); border: 1px solid color-mix(in srgb, var(--amber) 40%, transparent); }
.part-head { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 14px; align-items: start; }
.part-main { display: grid; gap: 10px; min-width: 0; }
.part-side { display: grid; gap: 6px; justify-items: end; }
.part-num { display: inline-block; font-family: var(--font-mono); font-weight: 600; color: var(--accent); margin-right: 10px; }
.qtext { font-weight: 700; font-size: 1.06rem; max-width: 72ch; display: grid; gap: 8px; }
.qtext p { margin: 0; }
.stem { color: var(--ink); font-style: normal; display: grid; gap: 6px; max-width: 72ch; padding-left: 12px; border-left: 3px solid var(--line); }
.cmd { font-size: .78rem; font-family: var(--font-mono); text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.part-meta { display: flex; flex-wrap: wrap; gap: 4px 14px; font-family: var(--font-mono); font-size: .78rem; color: var(--muted); border-top: 1px dashed var(--line); padding-top: 8px; }
.part-meta a { color: inherit; }
.lead { display: grid; gap: 8px; font-size: 1.02rem; max-width: 80ch; }
.lead.card { border-left: 4px solid var(--accent); }
.lead.plain { padding: 0 0 6px; }
@media (max-width: 520px) { .part-head { grid-template-columns: 1fr; } .part-side { justify-items: start; grid-auto-flow: column; justify-content: start; align-items: center; gap: 10px; } }

/* answers */
.answer-line { grid-template-columns: minmax(0, 1fr); gap: 4px; }
.answer-line label { font-family: var(--font-body); color: var(--muted); font-size: .92rem; font-weight: 700; }
.answer-line textarea { min-height: 64px; }
textarea { min-height: 120px; }
select { font: inherit; color: var(--ink); background: var(--surface); border: 1.5px solid var(--line); border-radius: var(--radius-sm); padding: 8px 10px; min-height: 44px; width: 100%; }
select:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-soft); }

/* official visuals */
.diagram { display: grid; gap: 6px; justify-items: start; }
.zoomable { padding: 0; border: 1px solid var(--line); background: var(--plate); border-radius: var(--radius-sm); cursor: zoom-in; display: block; max-width: 100%; }
.diagram img { display: block; max-height: 320px; width: auto; max-width: 100%; padding: 10px; }
figcaption .src, .dtable .src { font-family: var(--font-mono); font-size: .74rem; color: var(--muted); font-weight: 400; margin-left: 6px; }
figcaption { font-weight: 700; font-size: .92rem; }
.dtable { display: grid; gap: 8px; }
.grid-table { border: 1px solid var(--line); background: var(--surface); }
.grid-table th, .grid-table td { border: 1px solid var(--line); text-align: center !important; padding: 7px 10px; font-family: var(--font-mono); font-size: .9rem; }
.grid-table thead th { background: var(--surface-2); font-weight: 600; }
.grid-table tbody th { background: var(--surface-2); font-weight: 600; }

/* mark scheme */
.scheme { display: grid; gap: 12px; border-top: 2px solid var(--accent); padding-top: 14px; }
.scheme-head { display: flex; justify-content: space-between; gap: 10px; flex-wrap: wrap; align-items: baseline; }
.scheme-head .eyebrow { color: var(--accent); font-weight: 600; }
.scope { background: var(--amber-soft); border-radius: var(--radius-sm); padding: 8px 12px; font-size: .94rem; }
.scheme-sec { display: grid; gap: 10px; }
.ms-pages { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 340px), 1fr)); }
.ms-page { position: relative; }
.ms-page img { display: block; width: 100%; height: auto; }
.ms-cap { position: absolute; left: 8px; bottom: 8px; background: var(--ink); color: var(--bg); font-family: var(--font-mono); font-size: .72rem; padding: 2px 8px; border-radius: 3px; }
.ms-text summary { cursor: pointer; font-weight: 700; color: var(--accent); min-height: 32px; display: flex; align-items: center; }
.ms-text pre { white-space: pre-wrap; overflow-wrap: anywhere; font-family: var(--font-mono); font-size: .82rem; line-height: 1.5; background: var(--surface-2); padding: 12px 14px; border-radius: var(--radius-sm); margin: 6px 0; max-height: 420px; overflow: auto; }
.selfmark { display: grid; gap: 8px; background: var(--surface-2); border-radius: var(--radius-sm); padding: 12px 14px; }
.sm-label { font-weight: 700; }
.sm-opts { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.sm-opts button { font: inherit; font-family: var(--font-mono); font-weight: 600; min-width: 44px; min-height: 44px; border-radius: var(--radius-sm); border: 1.5px solid var(--line); background: var(--surface); color: var(--ink); cursor: pointer; }
.sm-opts button:hover { border-color: var(--accent); }
.sm-opts button[aria-pressed="true"] { background: var(--amber); border-color: var(--amber); color: var(--accent-ink); }
.sm-of { font-family: var(--font-mono); color: var(--muted); margin-left: 4px; }

/* zoom overlay */
.zoom { position: fixed; inset: 0; z-index: 60; background: rgba(8, 14, 20, .82); display: grid; place-items: center; padding: max(16px, env(safe-area-inset-top, 0px)) max(16px, env(safe-area-inset-right, 0px)) max(16px, env(safe-area-inset-bottom, 0px)) max(16px, env(safe-area-inset-left, 0px)); overflow: auto; }
.zoom img { max-width: min(100%, 1100px); max-height: none; background: #fff; border-radius: 4px; }
.zoom button { position: fixed; top: calc(env(safe-area-inset-top, 0px) + 12px); right: calc(env(safe-area-inset-right, 0px) + 12px); }

/* finder */
.filters { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 180px), 1fr)); align-items: end; }
.field { display: grid; gap: 4px; }
.field label { font-size: .85rem; font-weight: 700; color: var(--muted); }

/* topic diagrams */
.tdiag { display: grid; gap: 10px; color: var(--ink); }
.tdiag svg { width: 100%; height: auto; }
.tdiag figcaption { font-weight: 400; color: var(--muted); font-size: .9rem; }
.hier { display: grid; gap: 4px; justify-items: center; }
.hier div { width: var(--w); background: var(--accent-soft); border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent); text-align: center; padding: 7px 6px; font-weight: 700; font-size: .95rem; border-radius: 3px; }
.hier div:first-child { background: var(--good-soft); border-color: var(--good); }
.hier div:last-child { background: var(--amber-soft); border-color: var(--amber); }
.pdca { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.pdca div { border: 1.5px solid var(--accent); border-radius: var(--radius); padding: 10px 12px; display: grid; gap: 2px; background: var(--surface); }
.pdca strong { font-family: var(--font-display); font-size: 1.2rem; color: var(--accent); }
.pdca span { font-size: .9rem; color: var(--muted); }
.lines-table td:first-child { width: 100px; }

/* misc */
.tag-original { justify-self: start; font-family: var(--font-mono); font-size: .72rem; text-transform: uppercase; letter-spacing: .07em; background: var(--surface-2); border: 1px dashed var(--muted); color: var(--muted); padding: 2px 8px; border-radius: 3px; }
.quiz-q { font-size: 1.5rem; }
.rule { border: 0; border-top: 1px solid var(--line); margin: 0; }
.cmd-item h3 { font-family: var(--font-display); font-size: 1.3rem; letter-spacing: .04em; color: var(--accent); display: grid; }
.cmd-item h3 small { font-family: var(--font-mono); font-size: .72rem; color: var(--muted); letter-spacing: 0; text-transform: none; font-weight: 400; }
.worked { background: var(--surface-2); border-radius: var(--radius-sm); padding: 12px 14px; display: grid; gap: 6px; }
.qnav button { border-radius: var(--radius-sm); }
.qnav button.flagged::after { content: ""; position: absolute; top: -4px; right: -4px; width: 12px; height: 12px; border-radius: 50%; background: var(--red); border: 2px solid var(--surface); }
.legend i.f { background: var(--red); border-color: var(--red); border-radius: 50%; }
[data-flag][aria-pressed="true"] { border-color: var(--red); color: var(--red); }
.sec-break td { border-top: 2px solid var(--ink); }
.pctbar { display: inline-block; width: 60px; height: 6px; background: var(--surface-2); border-radius: 3px; vertical-align: middle; margin-left: 6px; overflow: hidden; }
.pctbar span { display: block; height: 100%; background: var(--amber); }
.footer a { color: inherit; }
.review-part { gap: 12px; }

.brand-name { max-width: 34ch; }
@media (max-width: 520px) { .brand { font-size: 1.05rem; } .brand-name { max-width: 24ch; } }