/* gks.bdfz.net — dark technical / "geeky" UI.
   Mono accents, coverage-matrix density, teal terminal accent. Class names kept
   stable so app.js logic is untouched. */

:root {
  --bg: #0a0e15;
  --bg-grid: rgba(120,150,190,.04);
  --surface: #111726;
  --surface-2: #161e30;
  --surface-3: #1d273b;
  --border: #232d42;
  --border-2: #303d57;
  --ink: #d9e1ef;
  --ink-dim: #9aa7c0;
  --muted: #61708e;

  --accent: #34d3bb;          /* teal terminal accent */
  --accent-2: #54a8ff;        /* link blue */
  --accent-ink: #6ff0db;
  --accent-dim: rgba(52,211,187,.13);
  --accent-line: rgba(52,211,187,.30);

  --good: #46d39a;
  --good-dim: rgba(70,211,154,.13);
  --bad: #ff6b6b;
  --bad-dim: rgba(255,107,107,.12);
  --warn: #f2b14a;
  --warn-dim: rgba(242,177,74,.12);

  --mono: ui-monospace, "JetBrains Mono", "SFMono-Regular", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
          "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;

  --radius: 10px;
  --radius-sm: 7px;
  --shadow: 0 14px 40px -18px rgba(0,0,0,.7);
  --maxw: 820px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--font);
  color: var(--ink);
  background:
    linear-gradient(var(--bg-grid) 1px, transparent 1px) 0 0 / 100% 30px,
    radial-gradient(900px 500px at 88% -10%, rgba(52,211,187,.06), transparent 60%),
    radial-gradient(800px 500px at -5% 0%, rgba(84,168,255,.05), transparent 55%),
    var(--bg);
  background-attachment: fixed;
  line-height: 1.62;
  font-size: 15.5px;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent-2); text-decoration: none; }
a:hover { color: var(--accent-ink); }
img { max-width: 100%; height: auto; }
::selection { background: var(--accent-dim); }
code, kbd, .mono { font-family: var(--mono); }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 50;
  background: rgba(10,14,21,.82);
  backdrop-filter: saturate(1.3) blur(12px);
  border-bottom: 1px solid var(--border);
}
.topbar .inner { max-width: 1180px; margin: 0 auto; padding: 11px 20px; display: flex; align-items: center; gap: 14px; }
.brand { display: flex; align-items: center; gap: 10px; cursor: pointer; }
.brand .logo {
  width: 32px; height: 32px; border-radius: 8px; flex: none;
  background: linear-gradient(150deg, #0e2b2a, #103a4a);
  border: 1px solid var(--accent-line);
  color: var(--accent); display: grid; place-items: center; font: 700 14px/1 var(--mono);
  box-shadow: inset 0 0 14px rgba(52,211,187,.18);
}
.brand .name { font: 700 14.5px/1.15 var(--mono); color: var(--ink); letter-spacing: -.01em; }
.brand .sub { font: 500 11px/1.3 var(--mono); color: var(--muted); }
.topbar .spacer { flex: 1; }
.navlink { color: var(--ink-dim); font: 500 13px/1 var(--mono); padding: 7px 11px; border-radius: 7px; cursor: pointer; transition: .14s; }
.navlink:hover { background: var(--surface-2); color: var(--ink); }
.navlink.active { color: var(--accent); background: var(--accent-dim); }
.who { font: 500 12px/1 var(--mono); color: var(--muted); }

/* ---------- layout ---------- */
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 22px 18px 100px; }
.wrap.wide { max-width: 1180px; }
.row { display: flex; gap: 12px; flex-wrap: wrap; }
.grid { display: grid; gap: 12px; }
.grid.cols { grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); }
.muted { color: var(--muted); }
.small { font-size: 12.5px; }
.center { text-align: center; }
.spacer { flex: 1; }
.mono-num { font-family: var(--mono); font-variant-numeric: tabular-nums; }

/* ---------- cards / tiles ---------- */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); }
.card.pad { padding: 17px; }
.tile {
  position: relative; overflow: hidden; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 15px; cursor: pointer; transition: .15s;
}
.tile:hover { border-color: var(--accent-line); background: var(--surface-2); transform: translateY(-2px); }
.tile h3 { margin: 0 0 4px; font-size: 15px; font-weight: 650; color: var(--ink); }
.tile p { margin: 0; font-size: 12.5px; color: var(--muted); }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 7px;
  border: 1px solid var(--border-2); background: var(--surface-2); color: var(--ink);
  border-radius: 8px; padding: 9px 15px; font: 600 13.5px/1.2 var(--font); cursor: pointer; transition: .13s;
}
.btn:hover { border-color: var(--accent-line); color: var(--accent-ink); }
.btn.primary, .btn.accent { background: linear-gradient(160deg, #103a3a, #0f5350); border-color: var(--accent-line); color: var(--accent-ink); }
.btn.primary:hover, .btn.accent:hover { box-shadow: 0 0 0 1px var(--accent-line), 0 6px 18px -8px rgba(52,211,187,.5); color: #bff8ec; }
.btn.ghost { background: transparent; border-color: transparent; color: var(--accent-2); }
.btn.ghost:hover { background: var(--surface-2); }
.btn.sm { padding: 6px 11px; font-size: 12.5px; border-radius: 7px; }
.btn.block { width: 100%; }
.btn:disabled { opacity: .45; cursor: not-allowed; }

/* ---------- chips / pills ---------- */
.chips { display: flex; flex-wrap: wrap; gap: 7px; }
.chip {
  display: inline-flex; align-items: center; gap: 5px; padding: 5px 11px; border-radius: 7px;
  background: var(--surface-2); border: 1px solid var(--border); color: var(--ink-dim);
  font: 500 12.5px/1.4 var(--mono); cursor: pointer; transition: .13s; user-select: none;
}
.chip:hover { border-color: var(--accent-line); color: var(--ink); }
.chip.on { background: var(--accent-dim); border-color: var(--accent-line); color: var(--accent-ink); }
.pill { display: inline-flex; align-items: center; gap: 4px; padding: 2px 8px; border-radius: 6px; font: 600 11px/1.7 var(--mono); }
.pill.navy { background: var(--accent-dim); color: var(--accent-ink); }
.pill.good { background: var(--good-dim); color: var(--good); }
.pill.bad { background: var(--bad-dim); color: var(--bad); }
.pill.warn { background: var(--warn-dim); color: var(--warn); }
.pill.gray { background: var(--surface-2); color: var(--ink-dim); border: 1px solid var(--border); }

/* ---------- headings ---------- */
.page-head { margin-bottom: 18px; }
.page-head h1 { font-size: 21px; margin: 0 0 4px; color: var(--ink); font-weight: 700; letter-spacing: -.01em; }
.page-head .crumbs { font: 500 12.5px/1.4 var(--mono); color: var(--muted); }
.crumbs a { color: var(--accent-2); }
.section-title {
  font: 600 11.5px/1 var(--mono); color: var(--muted); margin: 26px 0 11px;
  letter-spacing: .12em; text-transform: uppercase; display: flex; align-items: center; gap: 8px;
}
.section-title::before { content: "▍"; color: var(--accent); }

/* ---------- home masthead (terse) ---------- */
.masthead { padding: 4px 0 2px; }
.masthead .tag { font: 500 12px/1 var(--mono); color: var(--accent); letter-spacing: .04em; }
.masthead h1 { margin: 8px 0 4px; font-size: 24px; font-weight: 750; letter-spacing: -.02em; color: var(--ink); }
.masthead p { margin: 0; color: var(--ink-dim); font-size: 14px; max-width: 600px; }

/* stat strip */
.statstrip { display: flex; gap: 0; flex-wrap: wrap; margin: 16px 0 4px; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; background: var(--surface); }
.statstrip .s { flex: 1; min-width: 86px; padding: 12px 15px; border-right: 1px solid var(--border); }
.statstrip .s:last-child { border-right: 0; }
.statstrip .s b { display: block; font: 700 22px/1 var(--mono); color: var(--accent); letter-spacing: -.02em; }
.statstrip .s span { font: 500 11px/1.4 var(--mono); color: var(--muted); }

/* ---------- coverage matrix ---------- */
.matrix-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
table.matrix { border-collapse: collapse; width: 100%; font-family: var(--mono); font-size: 12px; }
table.matrix th, table.matrix td { text-align: center; padding: 0; border: 1px solid var(--border); }
table.matrix thead th { color: var(--muted); font-weight: 600; padding: 9px 6px; white-space: nowrap; background: var(--surface-2); position: sticky; top: 0; }
table.matrix th.yr { color: var(--accent); padding: 0 12px; background: var(--surface-2); font-weight: 700; }
table.matrix td .cell { display: block; height: 38px; line-height: 38px; cursor: default; color: var(--surface-3); user-select: none; }
table.matrix td.has .cell { color: var(--accent-ink); background: var(--accent-dim); cursor: pointer; font-weight: 700; }
table.matrix td.has .cell:hover { background: rgba(52,211,187,.26); box-shadow: inset 0 0 0 1px var(--accent-line); }
table.matrix td.miss .cell { color: var(--surface-3); }
table.matrix td.miss .cell::after { content: "·"; }

.coverage-board {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}
.coverage-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface);
}
.coverage-row > div { min-width: 0; }
.coverage-row b {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--ink);
  font: 650 12px/1.35 var(--mono);
}
.coverage-row div span {
  display: block;
  margin-top: 2px;
  color: var(--muted);
  font: 500 11px/1.35 var(--mono);
}

/* ---------- question ---------- */
.q-stem { font-size: 16px; line-height: 1.82; color: var(--ink); }
.material {
  background: var(--surface-2); border: 1px solid var(--border); border-left: 2px solid var(--accent);
  border-radius: 8px; padding: 13px 15px; margin: 13px 0; font-size: 14.5px; color: var(--ink-dim);
  white-space: pre-wrap; line-height: 1.78;
}
.q-meta { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; margin: 2px 0 13px; }
/* exam figures are light scans — keep a white panel so they read on the dark theme */
.q-images figure { margin: 13px 0; background: #fff; border: 1px solid var(--border-2); border-radius: 8px; padding: 8px; }
.q-images img { border-radius: 4px; cursor: zoom-in; }
.q-images figcaption { color: var(--muted); font-size: 12px; margin-top: 6px; }
.q-images figure.pdf-attachment { background: var(--surface-2); padding: 12px; }
.pdf-actions { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-bottom: 10px; }
.pdf-frame { display: block; width: 100%; height: min(72vh, 760px); border: 1px solid var(--border); border-radius: 7px; background: #fff; }

.opt {
  display: flex; gap: 11px; align-items: flex-start; padding: 12px 14px; margin: 8px 0;
  border: 1px solid var(--border); border-radius: 9px; cursor: pointer; background: var(--surface); transition: .12s;
}
.opt:hover { border-color: var(--accent-line); background: var(--surface-2); }
.opt.sel { border-color: var(--accent-line); background: var(--accent-dim); }
.opt.correct { border-color: var(--good); background: var(--good-dim); }
.opt.wrong { border-color: var(--bad); background: var(--bad-dim); }
.opt .key { flex: none; width: 25px; height: 25px; border-radius: 6px; background: var(--surface-3); display: grid; place-items: center; font: 700 13px/1 var(--mono); color: var(--ink-dim); }
.opt.sel .key { background: var(--accent); color: #04201c; }
.opt.correct .key { background: var(--good); color: #06210f; }
.opt.wrong .key { background: var(--bad); color: #2a0707; }
.opt .opt-text { min-width: 0; }
.opt .opt-text img {
  display: block;
  width: auto;
  max-width: min(100%, 520px);
  max-height: 180px;
  margin-top: 8px;
  padding: 6px;
  background: #fff;
  border: 1px solid var(--border-2);
  border-radius: 6px;
}

textarea, input[type=text], input[type=number], input[type=password], select {
  width: 100%; font-family: var(--font); font-size: 14.5px; color: var(--ink);
  border: 1px solid var(--border-2); border-radius: 8px; padding: 11px 12px; background: var(--bg-2, #0d1219); transition: .13s;
}
textarea { background: #0d1219; resize: vertical; min-height: 112px; line-height: 1.7; }
textarea:focus, input:focus, select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-dim); }
label.fld { display: block; font: 600 12px/1 var(--mono); color: var(--ink-dim); margin: 13px 0 6px; text-transform: uppercase; letter-spacing: .05em; }

.thumbs { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 11px; }
.thumb { position: relative; width: 80px; height: 80px; border-radius: 8px; overflow: hidden; border: 1px solid var(--border-2); }
.thumb img { width: 100%; height: 100%; object-fit: cover; }
.thumb .x { position: absolute; top: 3px; right: 3px; background: rgba(0,0,0,.7); color: #fff; width: 18px; height: 18px; border-radius: 50%; display: grid; place-items: center; font-size: 12px; cursor: pointer; }

/* ---------- grade ---------- */
.grade { border-radius: 10px; padding: 16px; margin-top: 16px; border: 1px solid var(--border); background: var(--surface-2); }
.grade.ok { border-color: rgba(70,211,154,.4); box-shadow: inset 0 0 0 1px var(--good-dim); }
.grade.no { border-color: rgba(255,107,107,.4); box-shadow: inset 0 0 0 1px var(--bad-dim); }
.grade.partial { border-color: rgba(242,177,74,.4); }
.grade h3 { margin: 0 0 11px; display: flex; align-items: center; gap: 8px; font-size: 16px; font-weight: 700; }
.grade .score { font: 800 21px/1 var(--mono); letter-spacing: -.02em; }
.kv { margin: 11px 0; }
.kv .k { font: 700 11px/1 var(--mono); color: var(--accent); margin-bottom: 4px; text-transform: uppercase; letter-spacing: .06em; }
.kv .v { font-size: 14.5px; color: var(--ink); line-height: 1.72; }
.kv ul { margin: 5px 0; padding-left: 19px; }
.kv li { margin: 3px 0; }
.collapse-head { cursor: pointer; display: flex; align-items: center; gap: 7px; font: 700 13px/1 var(--mono); color: var(--accent); text-transform: uppercase; letter-spacing: .04em; }
.collapse-head .caret { transition: .15s; }
.collapse.closed .collapse-body { display: none; }
.collapse.closed .caret { transform: rotate(-90deg); }

/* ---------- chat ---------- */
.chat { margin-top: 15px; }
.msg { padding: 11px 14px; border-radius: 10px; margin: 8px 0; max-width: 92%; font-size: 14px; line-height: 1.72; }
.msg.user { background: var(--accent-dim); border: 1px solid var(--accent-line); color: var(--ink); margin-left: auto; }
.msg.assistant { background: var(--surface-2); border: 1px solid var(--border); }
.chat-input { display: flex; gap: 8px; margin-top: 9px; }
.chat-input textarea { min-height: 44px; }
.ai-disclaimer { font: 500 11.5px/1.5 var(--mono); color: var(--muted); margin-top: 7px; }

/* ---------- exam bar / timer ---------- */
.exam-bar {
  position: sticky; top: 56px; z-index: 30; background: rgba(17,23,38,.9); backdrop-filter: blur(10px);
  border: 1px solid var(--border); border-radius: 10px; padding: 10px 14px; margin-bottom: 14px; display: flex; align-items: center; gap: 12px;
}
.timer { font: 800 19px/1 var(--mono); color: var(--accent); font-variant-numeric: tabular-nums; }
.timer.warn { color: var(--bad); }
.qnav { display: flex; flex-wrap: wrap; gap: 6px; margin: 4px 0 14px; }
.qnav .b { width: 33px; height: 33px; border-radius: 7px; border: 1px solid var(--border); background: var(--surface); display: grid; place-items: center; font: 600 12.5px/1 var(--mono); cursor: pointer; color: var(--ink-dim); transition: .12s; }
.qnav .b:hover { border-color: var(--accent-line); }
.qnav .b.answered { background: var(--accent-dim); border-color: var(--accent-line); color: var(--accent-ink); }
.qnav .b.current { outline: 2px solid var(--accent); outline-offset: 1px; }

/* ---------- tables / report ---------- */
table.rep { width: 100%; border-collapse: collapse; font-size: 13.5px; }
table.rep th, table.rep td { text-align: left; padding: 9px 10px; border-bottom: 1px solid var(--border); }
table.rep th { color: var(--muted); font: 600 11px/1 var(--mono); text-transform: uppercase; letter-spacing: .04em; }
table.rep tr:last-child td { border-bottom: 0; }
table.rep td { font-family: var(--font); }
.bar { height: 7px; border-radius: 4px; background: var(--surface-3); overflow: hidden; }
.bar > span { display: block; height: 100%; background: linear-gradient(90deg, var(--accent), var(--accent-2)); }

/* ---------- credibility banner ---------- */
.cred-note { font: 500 12px/1.5 var(--mono); padding: 8px 11px; border-radius: 8px; margin: 9px 0; background: var(--warn-dim); color: var(--warn); border: 1px solid rgba(242,177,74,.3); }
.cred-note.low { background: var(--bad-dim); color: var(--bad); border-color: rgba(255,107,107,.3); }
.cred-note.ai { background: var(--accent-dim); color: var(--accent-ink); border-color: var(--accent-line); }

/* ---------- misc ---------- */
.spinner { width: 16px; height: 16px; border: 2px solid var(--surface-3); border-top-color: var(--accent); border-radius: 50%; animation: spin .7s linear infinite; display: inline-block; vertical-align: middle; }
@keyframes spin { to { transform: rotate(360deg); } }
.loading { display: flex; align-items: center; gap: 10px; color: var(--muted); padding: 26px 0; justify-content: center; font: 500 13px/1 var(--mono); }
.empty { text-align: center; color: var(--muted); padding: 46px 16px; }
.empty h2 { color: var(--ink-dim); font-weight: 700; }
.divider { height: 1px; background: var(--border); margin: 16px 0; border: 0; }
.toast { position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%) translateY(8px); z-index: 200; background: var(--surface-3); border: 1px solid var(--border-2); color: var(--ink); padding: 10px 17px; border-radius: 9px; font: 500 13px/1 var(--mono); box-shadow: var(--shadow); opacity: 0; transition: .25s; pointer-events: none; }
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.katex { font-size: 1.02em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 5px 0; }
.footnote { font: 500 11.5px/1.6 var(--mono); color: var(--muted); }

.actionbar { position: sticky; bottom: 0; background: rgba(10,14,21,.92); backdrop-filter: blur(8px); border-top: 1px solid var(--border); padding: 10px 18px; margin: 16px -18px -100px; display: flex; gap: 10px; }

/* ---------- mobile ---------- */
@media (max-width: 760px) {
  body { font-size: 15px; }
  .topbar .inner { padding: 10px 14px; gap: 8px; }
  .brand .sub { display: none; }
  .navlinks-desktop { display: none; }
  .wrap { padding: 16px 14px 96px; }
  .masthead h1 { font-size: 21px; }
  .grid.cols { grid-template-columns: 1fr 1fr; }
  .exam-bar { top: 52px; }
  .statstrip .s { min-width: 0; }
  .coverage-board { grid-template-columns: 1fr; }
}
@media (min-width: 761px) { .mobile-only { display: none; } }

/* bottom tab bar (mobile) */
.tabbar { display: none; position: fixed; bottom: 0; left: 0; right: 0; z-index: 60; background: rgba(10,14,21,.94); backdrop-filter: saturate(1.3) blur(14px); border-top: 1px solid var(--border); padding: 6px 4px calc(6px + env(safe-area-inset-bottom)); }
.tabbar a { flex: 1; text-align: center; color: var(--muted); font: 600 10px/1.3 var(--mono); padding: 4px 0; transition: .13s; }
.tabbar a .ic { font-size: 17px; display: block; line-height: 1.3; margin-bottom: 1px; filter: grayscale(.3); }
.tabbar a.active { color: var(--accent); }
@media (max-width: 760px) { .tabbar { display: flex; } }