/* ========== 变量 ========== */
:root {
  --bg: #f6f7f9;
  --bg-elev: #ffffff;
  --bg-soft: #f0f2f5;
  --text: #1a1f2b;
  --text-muted: #6b7280;
  --border: #e4e7ec;
  --border-strong: #cfd4dc;
  --primary: #2f6fed;
  --primary-hover: #245bd1;
  --primary-soft: #e8f0fe;
  --success: #1f9d55;
  --success-soft: #e6f6ec;
  --danger: #d64545;
  --danger-soft: #fdecec;
  --warning: #c77d0a;
  --warning-soft: #fdf3e0;
  --code-bg: #1b1f27;
  --code-text: #e6e9ef;
  --radius: 10px;
  --radius-sm: 6px;
  --font: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --dur: 180ms;
  --ease: cubic-bezier(0.2, 0.7, 0.2, 1);
}

[data-theme="dark"] {
  --bg: #0f1218;
  --bg-elev: #161a22;
  --bg-soft: #1d222c;
  --text: #e6e9ef;
  --text-muted: #949cab;
  --border: #272d39;
  --border-strong: #343c4b;
  --primary: #6f9cff;
  --primary-hover: #8db0ff;
  --primary-soft: #1d2a45;
  --success: #4fc082;
  --success-soft: #16322a;
  --danger: #f07a7a;
  --danger-soft: #3a1f21;
  --warning: #e3a44a;
  --warning-soft: #3a2c16;
  --code-bg: #0b0e13;
}

@media (prefers-reduced-motion: reduce) {
  :root { --dur: 0ms; }
  * { animation: none !important; transition: none !important; }
}

/* ========== 基础 ========== */
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
button { font-family: inherit; }
code, pre { font-family: var(--mono); }
.container { width: 100%; max-width: 1040px; margin: 0 auto; padding: 0 20px; }
main.container { flex: 1; padding-top: 24px; padding-bottom: 48px; }
.muted { color: var(--text-muted); }
.hidden { display: none !important; }

@keyframes fade-up { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
@keyframes fade-in { from { opacity: 0; } to { opacity: 1; } }
@keyframes pop { 0% { transform: scale(0.96); } 100% { transform: scale(1); } }
@keyframes slide-out { to { opacity: 0; transform: translateX(24px); max-height: 0; padding-top: 0; padding-bottom: 0; margin: 0; border-width: 0; } }
@keyframes shake { 0%, 100% { transform: translateX(0); } 25% { transform: translateX(-4px); } 75% { transform: translateX(4px); } }

#app > * { animation: fade-up var(--dur) var(--ease) both; }

/* ========== 页头 ========== */
.site-header { position: sticky; top: 0; z-index: 50; background: var(--bg-elev); border-bottom: 1px solid var(--border); }
.header-inner { display: flex; align-items: center; gap: 20px; height: 56px; }
.brand { display: flex; align-items: center; color: var(--text); }
.brand:hover { text-decoration: none; }
.brand-title { font-weight: 600; font-size: 15px; letter-spacing: -0.1px; }
.main-nav { display: flex; gap: 2px; margin-left: auto; }
.main-nav a {
  padding: 6px 12px; border-radius: var(--radius-sm); color: var(--text-muted); font-size: 14px; font-weight: 500;
  transition: background var(--dur), color var(--dur);
}
.main-nav a:hover { background: var(--bg-soft); color: var(--text); text-decoration: none; }
.main-nav a.active { color: var(--primary); background: var(--primary-soft); }
.icon-btn {
  width: 32px; height: 32px; border-radius: var(--radius-sm); border: 1px solid var(--border);
  background: var(--bg-elev); color: var(--text-muted); cursor: pointer; display: inline-flex; align-items: center; justify-content: center;
  transition: background var(--dur), color var(--dur);
}
.icon-btn:hover { background: var(--bg-soft); color: var(--text); }
.icon-btn svg { width: 17px; height: 17px; }
.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: inline; }

/* ========== 页脚 / 提示 ========== */
.site-footer { border-top: 1px solid var(--border); padding: 18px 0; color: var(--text-muted); font-size: 12.5px; text-align: center; }
.footer-inner { display: flex; flex-direction: column; gap: 6px; align-items: center; }
.site-footer p { margin: 0; }
.footer-credit { font-size: 12px; color: var(--text-muted); }
.footer-credit .mark {
  font-family: var(--mono); font-weight: 600; color: var(--text);
  letter-spacing: 0.2px;
}
.toast {
  position: fixed; left: 50%; bottom: 28px; transform: translateX(-50%) translateY(12px);
  background: var(--text); color: var(--bg-elev); padding: 9px 16px; border-radius: var(--radius-sm); font-size: 13.5px;
  opacity: 0; pointer-events: none; transition: opacity var(--dur), transform var(--dur) var(--ease); z-index: 100;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.loading { text-align: center; color: var(--text-muted); padding: 60px 0; }

/* ========== 通用组件 ========== */
.card { background: var(--bg-elev); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.card + .card { margin-top: 14px; }
.grid > .card, .grid > .card + .card { margin-top: 0; }
.card-title { margin: 0 0 12px; font-size: 16px; font-weight: 600; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.card-title .muted { font-size: 13px; font-weight: 400; }
.section-title { font-size: 17px; font-weight: 600; margin: 32px 0 12px; display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.section-title:first-child { margin-top: 0; }
.section-title small { font-size: 13px; color: var(--text-muted); font-weight: 400; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 7px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border-strong);
  background: var(--bg-elev); color: var(--text); font-size: 14px; font-weight: 500; cursor: pointer; line-height: 1.4; white-space: nowrap;
  transition: background var(--dur), border-color var(--dur), color var(--dur), transform 80ms;
}
.btn:hover { background: var(--bg-soft); text-decoration: none; }
.btn:active { transform: scale(0.98); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }
.btn-primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-hover); border-color: var(--primary-hover); }
.btn-success { background: var(--success); border-color: var(--success); color: #fff; }
.btn-danger { background: transparent; border-color: var(--border-strong); color: var(--danger); }
.btn-danger:hover { background: var(--danger-soft); border-color: var(--danger); }
.btn-ghost { background: transparent; border-color: transparent; color: var(--primary); }
.btn-ghost:hover { background: var(--primary-soft); }
.btn-sm { padding: 5px 10px; font-size: 13px; }
.btn-lg { padding: 10px 18px; font-size: 15px; }
.btn-group { display: flex; gap: 8px; flex-wrap: wrap; }

.badge {
  display: inline-flex; align-items: center; padding: 1px 8px; border-radius: 4px; font-size: 12px; font-weight: 500;
  background: var(--bg-soft); color: var(--text-muted); white-space: nowrap; flex: none;
}
.badge-primary { background: var(--primary-soft); color: var(--primary); }
.badge-success { background: var(--success-soft); color: var(--success); }
.badge-danger { background: var(--danger-soft); color: var(--danger); }
.badge-warning { background: var(--warning-soft); color: var(--warning); }

.progress { height: 6px; background: var(--bg-soft); border-radius: 3px; overflow: hidden; }
.progress > span { display: block; height: 100%; background: var(--primary); border-radius: 3px; transition: width 300ms var(--ease); }
.progress.success > span { background: var(--success); }

.chip-list { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex; align-items: center; gap: 6px; padding: 5px 11px; border-radius: 999px;
  border: 1px solid var(--border-strong); background: var(--bg-elev); color: var(--text); font-size: 13px; cursor: pointer;
  transition: background var(--dur), border-color var(--dur), color var(--dur);
}
.chip:hover { border-color: var(--primary); color: var(--primary); text-decoration: none; }
.chip.active { background: var(--primary-soft); border-color: var(--primary); color: var(--primary); }
.chip .count { color: var(--text-muted); font-size: 12px; }
.chip .acc { font-size: 12px; font-weight: 600; }

.empty { text-align: center; color: var(--text-muted); padding: 48px 20px; }
.empty .emoji { font-size: 34px; display: block; margin-bottom: 8px; }

.grid { display: grid; gap: 14px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

table.data-table { border-collapse: collapse; width: 100%; font-size: 14px; margin: 12px 0; }
table.data-table th, table.data-table td { border: 1px solid var(--border); padding: 6px 10px; text-align: left; }
table.data-table th { background: var(--bg-soft); font-weight: 600; }

input.text-input {
  width: 100%; padding: 8px 11px; border-radius: var(--radius-sm); border: 1px solid var(--border-strong);
  background: var(--bg-elev); color: var(--text); font-size: 14.5px; font-family: var(--mono); outline: none;
  transition: border-color var(--dur), box-shadow var(--dur);
}
input.text-input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-soft); }
input.text-input:disabled { background: var(--bg-soft); color: var(--text-muted); }

/* ========== 首页 ========== */
.hero { padding: 28px 24px; }
.hero h1 { margin: 0 0 6px; font-size: 26px; font-weight: 700; letter-spacing: -0.2px; }
.hero p { margin: 0 0 18px; color: var(--text-muted); font-size: 15px; max-width: 640px; }
.hero-stats { display: flex; gap: 0; margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--border); flex-wrap: wrap; }
.hero-stat { padding-right: 32px; }
.hero-stat + .hero-stat { padding-left: 32px; border-left: 1px solid var(--border); }
.hero-stat .num { font-size: 22px; font-weight: 700; line-height: 1.1; font-variant-numeric: tabular-nums; }
.hero-stat .label { font-size: 12.5px; color: var(--text-muted); margin-top: 2px; }

.paper-card { display: flex; flex-direction: column; gap: 10px; transition: border-color var(--dur); }
.paper-card:hover { border-color: var(--border-strong); }
.paper-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; }
.paper-date { font-size: 19px; font-weight: 700; letter-spacing: 0.2px; font-variant-numeric: tabular-nums; }
.paper-name { font-size: 13px; color: var(--text-muted); margin-top: 1px; }
.paper-meta { display: flex; gap: 10px; font-size: 13px; color: var(--text-muted); flex-wrap: wrap; }
.paper-progress { display: flex; align-items: center; gap: 10px; font-size: 12.5px; color: var(--text-muted); }
.paper-progress .progress { flex: 1; }
.paper-actions { display: flex; gap: 8px; margin-top: auto; }
.paper-actions .btn { flex: 1; }

/* ========== 练习页 ========== */
.practice-layout { display: grid; grid-template-columns: minmax(0, 1fr) 260px; gap: 16px; align-items: start; }
.practice-top { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 14px; flex-wrap: wrap; }
.practice-top .title { font-weight: 600; font-size: 16px; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.practice-top .progress { width: 100%; margin-top: 4px; }

.question-card { padding: 22px 24px; }
.q-head { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.q-no { font-size: 17px; font-weight: 700; color: var(--primary); }
.q-tags { display: flex; gap: 6px; flex-wrap: wrap; }
.q-head .spacer { flex: 1; }
.fav-btn { color: var(--text-muted); }
.fav-btn.active { color: var(--warning); }
.q-stem { font-size: 16px; line-height: 1.8; word-break: break-word; }
.q-stem code, .options code, .sub-stem code, .explain code, .wrong-item code, .w-answer code {
  background: var(--bg-soft); padding: 1px 5px; border-radius: 4px; font-size: 0.92em; color: var(--text);
}

pre.code {
  background: var(--code-bg); color: var(--code-text); padding: 14px 16px; border-radius: var(--radius-sm);
  overflow-x: auto; font-size: 14px; line-height: 1.7; margin: 12px 0; tab-size: 4;
}
pre.code .tok-k { color: #c792ea; }
pre.code .tok-b { color: #82aaff; }
pre.code .tok-s { color: #c3e88d; }
pre.code .tok-n { color: #f78c6c; }
pre.code .tok-c { color: #7f8ea3; font-style: italic; }
pre.code .blank {
  display: inline-block; min-width: 60px; text-align: center; padding: 0 6px; margin: 0 2px;
  border-bottom: 2px solid #f0b429; color: #f0b429; font-weight: 700; border-radius: 3px 3px 0 0;
}

.options { display: flex; flex-direction: column; gap: 8px; margin-top: 16px; }
.opt {
  display: flex; align-items: flex-start; gap: 12px; width: 100%; text-align: left;
  padding: 11px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border);
  background: var(--bg-elev); color: var(--text); font-size: 15px; cursor: pointer; line-height: 1.6;
  transition: border-color var(--dur), background var(--dur);
}
.opt:hover:not(:disabled) { border-color: var(--primary); }
.opt:disabled { cursor: default; }
.opt .letter {
  flex: none; width: 26px; height: 26px; border-radius: 50%; border: 1px solid var(--border-strong);
  display: inline-flex; align-items: center; justify-content: center; font-weight: 600; font-size: 13px; margin-top: 1px;
  color: var(--text-muted); transition: background var(--dur), color var(--dur), border-color var(--dur);
}
.opt.selected { border-color: var(--primary); background: var(--primary-soft); }
.opt.selected .letter { background: var(--primary); border-color: var(--primary); color: #fff; }
.opt.correct { border-color: var(--success); background: var(--success-soft); animation: pop var(--dur) var(--ease); }
.opt.correct .letter { background: var(--success); border-color: var(--success); color: #fff; }
.opt.wrong { border-color: var(--danger); background: var(--danger-soft); animation: shake 240ms var(--ease); }
.opt.wrong .letter { background: var(--danger); border-color: var(--danger); color: #fff; }
.opt .opt-text { flex: 1; }

.subs { margin-top: 14px; display: flex; flex-direction: column; gap: 14px; }
.sub { padding: 14px 16px; border: 1px solid var(--border); border-radius: var(--radius-sm); }
.sub-head { display: flex; align-items: center; gap: 8px; margin-bottom: 6px; font-weight: 600; }
.sub-head .badge { margin-left: auto; }
.sub-stem { font-size: 15px; }
.sub .options { margin-top: 10px; gap: 6px; }
.sub .opt { padding: 8px 12px; font-size: 14.5px; }
.blank-row { display: flex; align-items: center; gap: 10px; margin-top: 10px; flex-wrap: wrap; }
.blank-row .blank-label { font-weight: 700; color: var(--warning); width: 26px; }
.blank-row input { flex: 1; min-width: 180px; }
.blank-row .mark { font-weight: 600; font-size: 13.5px; }
.blank-row .mark.ok { color: var(--success); }
.blank-row .mark.bad { color: var(--danger); }
.blank-row .std { font-size: 13px; color: var(--text-muted); width: 100%; padding-left: 36px; }

.result-bar {
  margin-top: 16px; padding: 10px 14px; border-radius: var(--radius-sm); display: flex; align-items: center; gap: 8px; font-weight: 600; flex-wrap: wrap;
  animation: fade-up var(--dur) var(--ease);
}
.result-bar.ok { background: var(--success-soft); color: var(--success); }
.result-bar.bad { background: var(--danger-soft); color: var(--danger); }
.result-bar .score { margin-left: auto; font-size: 13.5px; font-weight: 500; }

.explain { margin-top: 12px; padding: 12px 14px; border-radius: var(--radius-sm); background: var(--bg-soft); font-size: 14.5px; animation: fade-in var(--dur) var(--ease); }
.explain .label { font-weight: 600; color: var(--primary); margin-bottom: 2px; font-size: 13px; }
.explain p { margin: 4px 0; }

.q-actions { display: flex; align-items: center; gap: 8px; margin-top: 18px; flex-wrap: wrap; }
.q-actions .spacer { flex: 1; }

.side-card { position: sticky; top: 72px; padding: 16px; }
.side-card .card-title { font-size: 14px; margin-bottom: 10px; }
.num-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 6px; }
.num-cell {
  height: 32px; border-radius: var(--radius-sm); border: 1px solid var(--border); background: var(--bg-elev);
  font-size: 13px; font-weight: 500; color: var(--text); cursor: pointer; display: inline-flex; align-items: center; justify-content: center;
  transition: border-color var(--dur), background var(--dur);
}
.num-cell:hover { border-color: var(--primary); text-decoration: none; }
.num-cell.current { border-color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }
.num-cell.ok { background: var(--success-soft); border-color: var(--success); color: var(--success); }
.num-cell.bad { background: var(--danger-soft); border-color: var(--danger); color: var(--danger); }
.num-cell.answered { background: var(--primary-soft); border-color: var(--primary); color: var(--primary); }
.legend { display: flex; gap: 10px; font-size: 12px; color: var(--text-muted); margin-top: 10px; flex-wrap: wrap; }
.legend span::before { content: ""; display: inline-block; width: 9px; height: 9px; border-radius: 2px; margin-right: 5px; vertical-align: -1px; }
.legend .l-ok::before { background: var(--success); }
.legend .l-bad::before { background: var(--danger); }
.legend .l-ans::before { background: var(--primary); }
.legend .l-none::before { background: var(--border-strong); }
.side-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 12px; }
.side-stat { border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 8px 10px; }
.side-stat .num { font-weight: 700; font-size: 17px; font-variant-numeric: tabular-nums; }
.side-stat .label { font-size: 12px; color: var(--text-muted); }
.kbd-hint { font-size: 12px; color: var(--text-muted); margin-top: 12px; line-height: 1.9; }
kbd { font-family: var(--mono); font-size: 11px; background: var(--bg-soft); border: 1px solid var(--border-strong); border-radius: 4px; padding: 0 5px; }

/* ========== 考试 ========== */
.exam-bar {
  position: sticky; top: 56px; z-index: 40; background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 10px 14px; display: flex; align-items: center; gap: 12px; margin-bottom: 16px; flex-wrap: wrap;
}
.exam-bar .timer { font-family: var(--mono); font-size: 18px; font-weight: 600; color: var(--primary); font-variant-numeric: tabular-nums; }
.exam-bar .timer.urgent { color: var(--danger); }
.exam-bar .spacer { flex: 1; }
.exam-q { margin-bottom: 14px; }
.exam-section-title { font-size: 16px; font-weight: 600; margin: 24px 0 12px; }

.score-hero { text-align: center; padding: 32px 20px; }
.score-hero .big { font-size: 56px; font-weight: 700; line-height: 1; color: var(--primary); font-variant-numeric: tabular-nums; }
.score-hero .big small { font-size: 20px; color: var(--text-muted); font-weight: 500; }
.score-hero .sub { color: var(--text-muted); margin-top: 8px; font-size: 14px; }
.score-row { display: flex; justify-content: center; gap: 0; margin-top: 20px; flex-wrap: wrap; }
.score-row .item { padding: 0 24px; }
.score-row .item + .item { border-left: 1px solid var(--border); }
.score-row .item .num { font-size: 20px; font-weight: 700; font-variant-numeric: tabular-nums; }
.score-row .item .label { font-size: 12.5px; color: var(--text-muted); }

/* ========== 错题本 / 收藏 ========== */
.list-toolbar { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-bottom: 12px; }
.list-toolbar .sep { width: 1px; height: 18px; background: var(--border-strong); margin: 0 4px; }
.list-card { padding: 0; overflow: hidden; }
.wrong-item {
  padding: 14px 18px; border-bottom: 1px solid var(--border); display: flex; gap: 14px; align-items: flex-start;
  max-height: 400px; transition: background var(--dur);
}
.wrong-item:last-child { border-bottom: none; }
.wrong-item:hover { background: var(--bg-soft); }
.wrong-item.removing { animation: slide-out 220ms var(--ease) forwards; pointer-events: none; overflow: hidden; }
.wrong-item .w-no { flex: none; width: 64px; font-weight: 600; color: var(--primary); font-size: 12.5px; line-height: 1.5; white-space: nowrap; }
.wrong-item .w-body { flex: 1; min-width: 0; }
.wrong-item .w-stem { display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; font-size: 14.5px; }
.wrong-item .w-meta { display: flex; gap: 8px; margin-top: 6px; flex-wrap: wrap; align-items: center; font-size: 12px; color: var(--text-muted); }
.wrong-item .w-answer { display: flex; gap: 12px; margin-top: 6px; font-size: 13px; flex-wrap: wrap; }
.wrong-item .w-answer .mine { color: var(--danger); }
.wrong-item .w-answer .right { color: var(--success); }
.wrong-item .w-actions { flex: none; display: flex; gap: 6px; }
.wrong-item .w-toggle { margin-top: 8px; }
.wrong-item .w-detail { margin-top: 10px; padding-top: 10px; border-top: 1px dashed var(--border); animation: fade-in var(--dur) var(--ease); }
.wrong-item .w-detail .options { margin-top: 8px; gap: 6px; }
.wrong-item .w-detail .opt { padding: 7px 10px; font-size: 14px; }

.stat-cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.stat-card { background: var(--bg-elev); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; }
.stat-card .num { font-size: 26px; font-weight: 700; line-height: 1.1; font-variant-numeric: tabular-nums; }
.stat-card .label { color: var(--text-muted); font-size: 12.5px; margin-top: 4px; }
.tag-row { display: grid; grid-template-columns: 140px 1fr 90px; align-items: center; gap: 12px; padding: 7px 0; border-bottom: 1px solid var(--border); font-size: 14px; }
.tag-row:last-child { border-bottom: none; }
.tag-row .name { font-weight: 500; }
.tag-row .val { text-align: right; color: var(--text-muted); font-variant-numeric: tabular-nums; font-size: 13px; }

/* ========== 关于 ========== */
.prose { font-size: 15px; }
.prose h3 { margin: 20px 0 6px; font-size: 16px; }
.prose ul, .prose ol { padding-left: 22px; }
.prose li { margin: 3px 0; }
.prose pre { background: var(--code-bg); color: var(--code-text); padding: 12px 14px; border-radius: var(--radius-sm); overflow-x: auto; font-size: 13px; }

/* ========== 响应式 ========== */
@media (max-width: 900px) {
  .practice-layout { grid-template-columns: 1fr; }
  .side-card { position: static; }
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .stat-cards { grid-template-columns: repeat(2, 1fr); }
  .num-grid { grid-template-columns: repeat(10, 1fr); }
}
@media (max-width: 600px) {
  .header-inner { gap: 10px; height: 52px; }
  .brand-title { font-size: 14px; }
  .main-nav a { padding: 5px 9px; font-size: 13.5px; }
  .hero { padding: 22px 18px; }
  .hero h1 { font-size: 22px; }
  .hero-stat { padding-right: 18px; }
  .hero-stat + .hero-stat { padding-left: 18px; }
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .question-card { padding: 16px; }
  .q-stem { font-size: 15px; }
  .tag-row { grid-template-columns: 100px 1fr 70px; }
  .num-grid { grid-template-columns: repeat(8, 1fr); }
  .wrong-item { flex-wrap: wrap; padding: 12px 14px; }
  .wrong-item .w-actions { width: 100%; }
  .exam-bar { top: 52px; }
  .score-hero .big { font-size: 44px; }
}

@media print {
  .site-header, .site-footer, .side-card, .q-actions, .exam-bar { display: none !important; }
}