:root {
  --bg: #f5f6f8;
  --card: #ffffff;
  --border: #e5e7eb;
  --text: #1f2329;
  --text-2: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --easy: #16a34a;
  --medium: #d97706;
  --hard: #dc2626;
  --pass: #16a34a;
  --fail: #dc2626;
  --code-bg: #f3f4f6;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  line-height: 1.6;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

code, pre, .mono {
  font-family: "SF Mono", Menlo, Consolas, "Courier New", monospace;
  font-size: 13px;
}

#app { max-width: 1440px; margin: 0 auto; padding: 16px 20px 48px; }

/* 做题页布局更宽一点 */
#app.app-wide { max-width: 1760px; }

/* ---------- 顶栏 ---------- */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0 18px;
}
.topbar .brand { font-size: 18px; font-weight: 700; }
.topbar .brand a { color: var(--text); }
.topbar .brand a:hover { text-decoration: none; }

/* ---------- 统计卡片 ---------- */
.stats { display: flex; gap: 12px; margin-bottom: 16px; flex-wrap: wrap; }
.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  min-width: 180px;
  flex: 1;
}
.stat-card .num { font-size: 24px; font-weight: 700; }
.stat-card .label { color: var(--text-2); font-size: 12px; margin-top: 2px; }
.stat-card .bar, .progress-summary .bar {
  height: 6px; background: var(--border); border-radius: 3px; margin-top: 8px; overflow: hidden;
}
.stat-card .bar > div, .progress-summary .bar > div { height: 100%; background: var(--primary); border-radius: 3px; }
.diff-counts { display: flex; gap: 10px; margin-top: 6px; font-size: 12px; color: var(--text-2); }

/* ---------- 筛选栏 ---------- */
.filters { display: flex; gap: 10px; margin-bottom: 14px; flex-wrap: wrap; }
.filters input[type="search"], .filters select {
  padding: 7px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--card);
  font-size: 13px;
  color: var(--text);
  outline: none;
}
.filters input[type="search"] { flex: 1; min-width: 200px; }
.filters input:focus, .filters select:focus { border-color: var(--primary); }

/* ---------- 题目列表 ---------- */
.plist { background: var(--card); border: 1px solid var(--border); border-radius: 10px; overflow: hidden; }
.plist-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 11px 16px;
  border-bottom: 1px solid var(--border);
}
.plist-row:last-child { border-bottom: none; }
.plist-row:hover { background: #fafbfc; }
.plist-row { cursor: pointer; }
.plist-row:hover .ptitle a { color: var(--primary); }
.plist-row .status { width: 22px; text-align: center; flex-shrink: 0; }
.plist-row .status .solved { color: var(--pass); font-weight: 700; }
.plist-row .status .attempted { color: var(--medium); }
.plist-row .pid { width: 36px; color: var(--text-2); flex-shrink: 0; }
.plist-row .ptitle { flex: 1; min-width: 0; }
.plist-row .ptitle a { color: var(--text); font-weight: 500; }
.plist-row .ptitle a:hover { color: var(--primary); }
.mode-badges { display: flex; gap: 4px; flex-shrink: 0; }
.mode-badge {
  font-size: 11px; padding: 1px 7px; border-radius: 4px;
  background: var(--code-bg); color: var(--text-2); border: 1px solid var(--border);
}
.mode-badge.done { background: #e8f7ee; color: var(--pass); border-color: #bfe6cd; }

.tag {
  font-size: 11px; padding: 1px 8px; border-radius: 10px;
  background: #eef2ff; color: #4f46e5;
}
.diff { font-size: 12px; font-weight: 600; flex-shrink: 0; width: 40px; text-align: right; }
.diff.easy { color: var(--easy); }
.diff.medium { color: var(--medium); }
.diff.hard { color: var(--hard); }
.row-tags { display: flex; gap: 5px; flex-shrink: 0; }
.empty-tip { padding: 40px; text-align: center; color: var(--text-2); }

/* ---------- 做题页 ---------- */
.phead { display: flex; align-items: center; gap: 14px; margin-bottom: 14px; flex-wrap: wrap; }
.phead .back { flex-shrink: 0; }
.phead h1 { font-size: 18px; font-weight: 700; }
.phead .head-tags { display: flex; gap: 6px; align-items: center; }
.phead .spacer { flex: 1; }

.seg { display: inline-flex; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; background: var(--card); }
.seg button {
  border: none; background: transparent; padding: 6px 14px; cursor: pointer;
  font-size: 13px; color: var(--text-2);
}
.seg button.active { background: var(--primary); color: #fff; }
.seg button:not(.active):hover { background: var(--code-bg); }

.pmain { display: grid; grid-template-columns: minmax(340px, 5fr) minmax(420px, 6fr); gap: 16px; align-items: start; }
@media (max-width: 900px) { .pmain { grid-template-columns: 1fr; } }

.panel { background: var(--card); border: 1px solid var(--border); border-radius: 10px; overflow: hidden; }
.panel-tabs { display: flex; border-bottom: 1px solid var(--border); }
.panel-tabs button {
  border: none; background: none; padding: 10px 18px; cursor: pointer;
  font-size: 13px; color: var(--text-2); border-bottom: 2px solid transparent;
}
.panel-tabs button.active { color: var(--primary); border-bottom-color: var(--primary); font-weight: 600; }
.panel-body { padding: 16px 18px; max-height: calc(100vh - 165px); overflow-y: auto; }

.desc h3 { margin: 14px 0 6px; font-size: 14px; }
.desc p { margin: 8px 0; }
.desc ul { padding-left: 20px; margin: 6px 0; }
.desc pre {
  background: var(--code-bg); border-radius: 6px; padding: 10px 12px;
  overflow-x: auto; margin: 8px 0; line-height: 1.5;
}
.desc code { background: var(--code-bg); padding: 1px 5px; border-radius: 4px; }
.desc pre code { background: none; padding: 0; }

.solution-block h3 { margin: 16px 0 6px; font-size: 14px; }
.solution-block h3:first-child { margin-top: 0; }
.solution-block pre {
  background: #0f172a; color: #e2e8f0; border-radius: 8px;
  padding: 12px 14px; overflow-x: auto; margin: 8px 0; line-height: 1.55;
}
.solution-block p, .solution-block ul { margin: 6px 0; }
.solution-block ul { padding-left: 20px; }
.solution-block code { background: var(--code-bg); padding: 1px 5px; border-radius: 4px; color: #c026d3; }
.solution-block pre code { background: none; padding: 0; color: inherit; }

.reveal-box { text-align: center; padding: 40px 16px; color: var(--text-2); }

/* ---------- 编辑区 ---------- */
.work { display: flex; flex-direction: column; gap: 12px; }
.editor-wrap {
  background: var(--card); border: 1px solid var(--border); border-radius: 10px;
  overflow: hidden;
}
.editor-toolbar {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 12px; border-bottom: 1px solid var(--border);
}
.editor-toolbar .hint { color: var(--text-2); font-size: 12px; flex: 1; }
#editor-host, .editor-host { height: clamp(420px, 52vh, 720px); }
.editor-fallback { width: 100%; height: 100%; border: none; outline: none; padding: 12px; resize: none; font-family: Menlo, Consolas, monospace; font-size: 13px; }

.actions { display: flex; gap: 10px; align-items: center; }
.btn {
  border: 1px solid var(--border); background: var(--card); color: var(--text);
  padding: 8px 18px; border-radius: 8px; cursor: pointer; font-size: 13px;
}
.btn:hover { background: var(--code-bg); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; font-weight: 600; }
.btn.primary:hover { background: var(--primary-hover); }
.btn:disabled { opacity: 0.55; cursor: not-allowed; }
.run-status { color: var(--text-2); font-size: 12px; }

/* ---------- 判题结果 ---------- */
.results { background: var(--card); border: 1px solid var(--border); border-radius: 10px; overflow: hidden; }
.results-head { padding: 10px 14px; border-bottom: 1px solid var(--border); font-weight: 600; display: flex; align-items: center; gap: 10px; }
.results-head .all-pass { color: var(--pass); }
.results-head .has-fail { color: var(--fail); }
.results-body { max-height: 300px; overflow-y: auto; padding: 10px 14px; }
.case {
  border: 1px solid var(--border); border-left-width: 3px; border-radius: 6px;
  padding: 8px 12px; margin-bottom: 8px;
}
.case.pass { border-left-color: var(--pass); }
.case.fail { border-left-color: var(--fail); }
.case .case-title { font-weight: 600; font-size: 12px; margin-bottom: 4px; }
.case .case-title .ok { color: var(--pass); }
.case .case-title .no { color: var(--fail); }
.case .kv { display: flex; gap: 8px; font-size: 12px; margin: 2px 0; }
.case .kv .k { color: var(--text-2); width: 62px; flex-shrink: 0; }
.case .kv pre { background: var(--code-bg); border-radius: 4px; padding: 2px 8px; overflow-x: auto; flex: 1; white-space: pre-wrap; word-break: break-all; }
.case .kv pre.err { color: var(--fail); }
.compile-error { padding: 14px; color: var(--fail); white-space: pre-wrap; }

/* ---------- 做题页：关联知识 / 提示锚点 / 模式说明 ---------- */
.related-knowledge { margin-top: 20px; padding-top: 14px; border-top: 1px solid var(--border); }
.related-knowledge h3 { margin: 0 0 8px; font-size: 14px; }
.related-knowledge ul { list-style: none; padding-left: 0; display: flex; flex-wrap: wrap; gap: 8px; }
.related-knowledge a {
  display: inline-block; padding: 4px 12px; font-size: 12.5px;
  border: 1px solid var(--border); border-radius: 14px; background: var(--card);
}
.related-knowledge a:hover { border-color: var(--primary); color: var(--primary); text-decoration: none; }
.hint-anchor { display: inline-block; margin-top: 8px; scroll-margin-top: 12px; }
.mode-note { color: var(--text-2); font-size: 12px; margin: 6px 0; }

/* ---------- 做题页：错题信息 / 复习横幅与复习导航 ---------- */
.mistake-info {
  margin: 10px 0; padding: 10px 14px; font-size: 12.5px; color: var(--text-2);
  border: 1px solid var(--border); border-left: 3px solid var(--medium); border-radius: 8px;
  background: color-mix(in srgb, var(--medium) 7%, var(--card));
}
.mistake-info strong { color: var(--text); }
.review-banner {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-bottom: 12px; padding: 10px 14px;
  border: 1px solid color-mix(in srgb, var(--primary) 45%, var(--border)); border-radius: 8px;
  background: color-mix(in srgb, var(--primary) 8%, var(--card));
}
.review-next, .result-next { display: inline-flex; align-items: center; gap: 8px; margin-top: 12px; font-weight: 600; }

/* ---------- 判题结果：错误角标 / 原始错误 / 标准输出 ---------- */
.error-badge {
  display: inline-block; font-size: 11px; font-weight: 600; padding: 1px 8px; border-radius: 10px;
  color: var(--fail); background: color-mix(in srgb, var(--fail) 12%, var(--card));
  border: 1px solid color-mix(in srgb, var(--fail) 35%, var(--border));
}
.raw-error, .stdout {
  margin: 6px 0; padding: 8px 12px; border-radius: 6px; border: 1px solid var(--border);
  background: var(--code-bg); overflow-x: auto;
  white-space: pre-wrap; word-break: break-all; font-size: 12.5px; line-height: 1.5;
}
.raw-error { color: var(--fail); border-color: color-mix(in srgb, var(--fail) 35%, var(--border)); }
.stdout { color: var(--text-2); }

/* ---------- 自定义测试：期望值 / diff / 空白符可视化 ---------- */
.custom-expected, .custom-diff {
  margin: 6px 0; padding: 8px 12px; border-radius: 6px;
  background: var(--code-bg); overflow-x: auto;
  white-space: pre-wrap; word-break: break-all; font-size: 12.5px; line-height: 1.55;
}
.whitespace, .custom-whitespace {
  color: var(--text-2); border-radius: 2px; padding: 0 1px;
  background: color-mix(in srgb, var(--text-2) 18%, transparent);
}

.footer-tip { text-align: center; color: var(--text-2); font-size: 12px; margin-top: 24px; }

/* ---------- 顶栏导航 ---------- */
.nav { display: flex; gap: 6px; }
.nav a {
  padding: 6px 14px; border-radius: 8px; color: var(--text-2);
  font-size: 13px; font-weight: 500;
}
.nav a:hover { background: var(--code-bg); text-decoration: none; }
.nav a.active { color: var(--primary); background: #eff6ff; font-weight: 600; }

/* ---------- 错题集 ---------- */
.mistakes-head {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 14px;
}
.mistakes-head h2 { font-size: 16px; }
.mistake-meta { color: var(--text-2); font-size: 12px; flex-shrink: 0; }
.btn.small { padding: 4px 12px; font-size: 12px; }

/* ---------- 分组视图（按标签 / 按难度） ---------- */
.pgroup { background: var(--card); border: 1px solid var(--border); border-radius: 10px; margin-bottom: 12px; overflow: hidden; }
.pgroup-head {
  display: flex; align-items: center; gap: 10px; width: 100%;
  border: none; background: none; padding: 12px 16px; cursor: pointer; font-size: 14px;
}
.pgroup-head:hover { background: #fafbfc; }
.pgroup-arrow { color: var(--text-2); width: 14px; }
.pgroup-name { font-weight: 600; flex: 1; text-align: left; }
.pgroup-diff { color: var(--text-2); font-size: 11.5px; margin-right: 12px; white-space: nowrap; }
.pgroup-count { color: var(--text-2); font-size: 12px; }
.pgroup-body { border-top: 1px solid var(--border); }
.pgroup-body .plist-row:last-child { border-bottom: none; }

/* ---------- 知识补充 ---------- */
.knowledge-intro { color: var(--text-2); margin-bottom: 16px; }
.kgrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; }
.kcard {
  display: block; position: relative; background: var(--card); border: 1px solid var(--border);
  border-radius: 10px; padding: 16px 18px; color: var(--text);
}
.kcard:hover { border-color: var(--primary); text-decoration: none; box-shadow: 0 2px 8px rgba(37, 99, 235, 0.08); }
.kcard-title { font-size: 15px; font-weight: 700; margin-bottom: 6px; }
.kcard-intro { color: var(--text-2); font-size: 12px; line-height: 1.6; margin-bottom: 10px; }
.kcard-tags { display: flex; gap: 5px; flex-wrap: wrap; align-items: center; }
.kcard-count { color: var(--text-2); font-size: 11px; margin-left: auto; }
.karticle { max-height: none; }
.krelated-title { margin: 24px 0 10px; font-size: 15px; }

/* 知识列表：关联错题角标（只在桌面端显示） */
.kcard-mistakes {
  position: absolute; top: 12px; right: 14px;
  font-size: 11px; font-weight: 600; padding: 1px 8px; border-radius: 10px;
  background: #fee2e2; color: var(--fail);
}

/* 知识详情：正文居中加宽；关联题和上一篇/下一篇放在正文末尾，用卡片网格展示 */
@media (min-width: 901px) {
  .karticle-main { max-width: 84ch; margin: 0 auto; }
  .karticle-related .plist { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 10px; background: transparent; border: none; overflow: visible; }
  .karticle-related .plist-row { background: var(--card); border: 1px solid var(--border); border-radius: 10px; flex-wrap: wrap; gap: 6px 8px; padding: 10px 12px; }
  .karticle-related .plist-row .row-tags { flex-basis: 100%; flex-wrap: wrap; min-width: 0; order: 5; }
  .karticle-main .pnav { margin-bottom: 4px; }
}

/* ---------- 左侧跳转目录（fixed 不占位，不影响排版） ---------- */
.dir-tab {
  position: fixed; left: 0; top: 45%; z-index: 1000;
  padding: 10px 7px;
  background: var(--card); color: var(--text-2);
  border: 1px solid var(--border); border-left: none; border-radius: 0 8px 8px 0;
  font-size: 13px; line-height: 1.3; cursor: pointer;
  writing-mode: vertical-rl; letter-spacing: 2px;
  box-shadow: 2px 2px 8px rgba(0, 0, 0, 0.12);
}
.dir-tab:hover { color: var(--primary); border-color: var(--primary); }

.dir-panel {
  position: fixed; left: 12px; top: 80px; z-index: 1100;
  width: min(320px, 78vw); max-height: min(76vh, 720px);
  display: flex; flex-direction: column;
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.18);
  overflow: hidden;
}
.dir-panel[hidden], .dir-tab[hidden] { display: none; }
.dir-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 8px 12px; border-bottom: 1px solid var(--border);
  font-size: 13px; font-weight: 600;
}
.dir-close { border: none; background: none; color: var(--text-2); cursor: pointer; font-size: 15px; padding: 0 2px; }
.dir-close:hover { color: var(--fail); }
.dir-body { overflow-y: auto; padding: 6px; }
.dir-group-head {
  position: sticky; top: -6px; z-index: 1;
  display: flex; align-items: baseline; gap: 6px;
  width: 100%; text-align: left;
  padding: 8px 8px 4px; margin-top: 2px;
  border: none; background: var(--card); cursor: pointer;
  font-size: 12px; font-weight: 600; color: var(--text-2);
}
.dir-group-head:hover { color: var(--primary); }
.dir-group:first-child .dir-group-head { margin-top: 0; }
.dir-group-arrow { width: 12px; flex-shrink: 0; }
.dir-group-count { margin-left: auto; font-weight: 400; }
.dir-row {
  display: flex; align-items: center; gap: 8px;
  width: 100%; text-align: left;
  border: none; background: none; padding: 6px 8px; border-radius: 8px;
  font-size: 13px; color: var(--text); cursor: pointer;
}
.dir-row:hover { background: var(--code-bg); }
.dir-row.active { background: var(--primary); color: #fff; }
.dir-row.active .diff, .dir-row.active .pid, .dir-row.active .dir-intro,
.dir-row.active .status, .dir-row.active .status span { color: #fff; }
.dir-row .status { width: 18px; text-align: center; flex-shrink: 0; }
.dir-row .status .solved { color: var(--pass); font-weight: 700; }
.dir-row .status .attempted { color: var(--medium); }
.dir-row .pid { width: 34px; color: var(--text-2); flex-shrink: 0; }
.dir-row .ptitle { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.dir-row .diff { flex-shrink: 0; }
.dir-row .dir-intro {
  flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
  color: var(--text-2); font-size: 12px;
}

/* 知识文章按语言偏好过滤代码块（未标记语言的代码块始终展示） */
.karticle[data-clang] pre[data-lang] { display: none; }
.karticle[data-clang='python'] pre[data-lang='python'],
.karticle[data-clang='javascript'] pre[data-lang='javascript'],
.karticle[data-clang='cpp'] pre[data-lang='cpp'] { display: block; }
.klang-label { color: var(--text-2); font-size: 12px; }

/* ---------- 暗色主题 ---------- */
[data-theme='dark'] {
  --bg: #0f172a;
  --card: #1e293b;
  --border: #334155;
  --text: #e2e8f0;
  --text-2: #94a3b8;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --code-bg: #0b1220;
  --easy: #4ade80;
  --medium: #fbbf24;
  --hard: #f87171;
  --pass: #4ade80;
  --fail: #f87171;
}
[data-theme='dark'] .tag { background: #312e81; color: #c7d2fe; }
[data-theme='dark'] .mode-badge { background: var(--code-bg); }
[data-theme='dark'] .mode-badge.done { background: #052e16; color: var(--pass); border-color: #14532d; }
[data-theme='dark'] .nav a.active { background: #1e3a8a; color: #bfdbfe; }
[data-theme='dark'] .plist-row:hover { background: #263449; }
[data-theme='dark'] .pgroup-head:hover { background: #263449; }
[data-theme='dark'] .kcard:hover { box-shadow: 0 2px 8px rgba(59, 130, 246, 0.25); }
[data-theme='dark'] .kcard-mistakes { background: #7f1d1d; color: #fecaca; }
[data-theme='dark'] .seg button:not(.active):hover { background: var(--code-bg); }
[data-theme='dark'] .btn:hover { background: var(--code-bg); }
[data-theme='dark'] .editor-fallback { background: var(--code-bg); color: var(--text); }
[data-theme='dark'] .case .kv pre { background: var(--code-bg); }
[data-theme='dark'] .desc code, [data-theme='dark'] .solution-block code { background: var(--code-bg); }
[data-theme='dark'] .diff-ok { background: #14532d; color: #bbf7d0; }
[data-theme='dark'] .diff-bad { background: #7f1d1d; color: #fecaca; }

/* ---------- 做题页：上一题/下一题、快捷键提示、编辑器拖高 ---------- */
.pnav { display: flex; justify-content: space-between; gap: 10px; margin-top: 14px; }
.pnav .btn { max-width: 48%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pnav .btn:hover { text-decoration: none; border-color: var(--primary); color: var(--primary); }
.kbd-hint { color: var(--text-2); font-size: 12px; }
kbd {
  background: var(--code-bg); border: 1px solid var(--border); border-bottom-width: 2px;
  border-radius: 4px; padding: 0 5px; font-family: inherit; font-size: 11px;
}
.editor-resize {
  height: 8px; cursor: ns-resize; display: flex; align-items: center; justify-content: center;
  border-top: 1px solid var(--border); background: var(--card);
}
.editor-resize::after { content: ''; width: 40px; height: 3px; border-radius: 2px; background: var(--border); }
.editor-resize:hover::after { background: var(--primary); }

/* ---------- 判题 diff 高亮 ---------- */
.diff-ok { background: #bbf7d0; color: #166534; border-radius: 2px; padding: 0 1px; }
.diff-bad { background: #fecaca; color: #991b1b; border-radius: 2px; padding: 0 1px; }

/* ---------- 列表页：状态筛选 chips 与工具按钮 ---------- */
.chips { display: inline-flex; gap: 6px; flex-wrap: wrap; }
.chips button {
  border: 1px solid var(--border); background: var(--card); color: var(--text-2);
  padding: 5px 12px; border-radius: 14px; cursor: pointer; font-size: 12px;
}
.chips button:hover { border-color: var(--primary); color: var(--primary); }
.chips button.active { background: var(--primary); border-color: var(--primary); color: #fff; }
.filters .tool-btn {
  border: 1px solid var(--border); background: var(--card); color: var(--text);
  padding: 7px 12px; border-radius: 8px; cursor: pointer; font-size: 13px;
}
.filters .tool-btn:hover { border-color: var(--primary); color: var(--primary); }

/* ---------- 知识页：学习步骤编号、卡片进度 ---------- */
.kcard-step {
  display: inline-block; font-size: 11px; color: var(--primary);
  background: rgba(37, 99, 235, 0.08); border-radius: 4px;
  padding: 1px 8px; margin-bottom: 8px; font-weight: 600;
}

/* ---------- Markdown 表格 ---------- */
.desc table, .karticle table { border-collapse: collapse; margin: 10px 0; font-size: 13px; }
.desc table th, .desc table td, .karticle table th, .karticle table td {
  border: 1px solid var(--border); padding: 5px 12px; text-align: left;
}
.desc table th, .karticle table th { background: var(--code-bg); font-weight: 600; white-space: nowrap; }

/* ---------- Markdown 提示框（callout） ---------- */
.callout {
  border-left: 3px solid var(--primary); border-radius: 0 8px 8px 0;
  padding: 10px 14px; margin: 10px 0; font-size: 13px;
}
.callout-title { font-weight: 700; margin-bottom: 3px; }
.callout-tip { border-color: #2563eb; background: rgba(37, 99, 235, 0.07); }
.callout-tip .callout-title { color: #2563eb; }
.callout-warn { border-color: #d97706; background: rgba(217, 119, 6, 0.08); }
.callout-warn .callout-title { color: #d97706; }
.callout-important { border-color: #dc2626; background: rgba(220, 38, 38, 0.07); }
.callout-important .callout-title { color: #dc2626; }
.callout-example { border-color: #16a34a; background: rgba(22, 163, 74, 0.07); }
.callout-example .callout-title { color: #16a34a; }

/* ---------- 可运行示例 ---------- */
.run-btn {
  border: 1px solid var(--border); background: var(--card); color: var(--primary);
  border-radius: 6px; padding: 3px 12px; font-size: 12px; cursor: pointer;
  margin: 4px 0 6px;
}
.run-btn:hover { border-color: var(--primary); }
.run-btn:disabled { opacity: 0.55; cursor: not-allowed; }
.run-out {
  background: #0f172a; color: #a5f3fc; border-radius: 8px;
  padding: 10px 14px; margin: 0 0 10px; font-size: 12.5px; line-height: 1.55;
  overflow-x: auto; white-space: pre-wrap; word-break: break-all;
}
.run-out .run-err { color: #fca5a5; }

/* ---------- 结果区：通过用例折叠 ---------- */
.passed-cases { margin-bottom: 8px; }
.passed-cases > summary {
  cursor: pointer; color: var(--pass); font-size: 12px; font-weight: 600;
  padding: 6px 10px; border: 1px dashed var(--border); border-radius: 6px;
  user-select: none; list-style: none;
}
.passed-cases > summary::before { content: '▸ '; }
.passed-cases[open] > summary::before { content: '▾ '; }
.passed-cases > summary:hover { border-color: var(--pass); }
.passed-cases[open] > summary { margin-bottom: 8px; }

/* ---------- 自定义测试 ---------- */
.custom-test {
  background: var(--card); border: 1px solid var(--border); border-radius: 10px;
  padding: 10px 14px;
}
.custom-test > summary { cursor: pointer; font-size: 13px; color: var(--text-2); user-select: none; list-style: none; }
.custom-test > summary::before { content: '▸ '; }
.custom-test[open] > summary::before { content: '▾ '; }
.custom-test > summary:hover { color: var(--primary); }
.custom-test textarea {
  width: 100%; margin-top: 10px; padding: 8px 10px; resize: vertical;
  border: 1px solid var(--border); border-radius: 6px; background: var(--bg); color: var(--text);
  font-family: Menlo, Consolas, monospace; font-size: 12.5px; outline: none;
}
.custom-test textarea:focus { border-color: var(--primary); }
.custom-actions { display: flex; align-items: center; gap: 10px; margin: 8px 0; }
.custom-out {
  background: #0f172a; color: #a5f3fc; border-radius: 8px;
  padding: 10px 14px; margin: 0 0 4px; font-size: 12.5px; line-height: 1.55;
  overflow-x: auto; white-space: pre-wrap; word-break: break-all;
}
.custom-out .run-err { color: #fca5a5; }

/* ---------- 题解代码复制按钮 ---------- */
.code-with-copy { position: relative; }
.copy-btn {
  position: absolute; top: 8px; right: 8px; z-index: 2;
  border: 1px solid rgba(255, 255, 255, 0.25); background: rgba(255, 255, 255, 0.08);
  color: #e2e8f0; border-radius: 6px; padding: 3px 10px; font-size: 12px; cursor: pointer;
}
.copy-btn:hover { background: rgba(255, 255, 255, 0.18); }

/* ---------- 数据导出/导入栏 ---------- */
.data-bar { display: flex; align-items: center; gap: 10px; justify-content: center; margin-top: 10px; }
.data-bar .tool-btn {
  border: 1px solid var(--border); background: var(--card); color: var(--text-2);
  padding: 5px 12px; border-radius: 8px; cursor: pointer; font-size: 12px;
}
.data-bar .tool-btn:hover { border-color: var(--primary); color: var(--primary); }
.data-tip { color: var(--text-2); font-size: 12px; }

/* ---------- 整合体验、无障碍与响应式 ---------- */
.skip-link {
  position: fixed; left: 12px; top: 8px; z-index: 2000; transform: translateY(-160%);
  padding: 7px 12px; border-radius: 6px; background: var(--primary); color: #fff;
}
.skip-link:focus { transform: translateY(0); }

:where(a, button, input, select, textarea, summary, [tabindex], [role='separator']):focus-visible {
  outline: 3px solid color-mix(in srgb, var(--primary) 68%, transparent);
  outline-offset: 2px;
}

.problem-storage-warning {
  margin-bottom: 12px; padding: 10px 14px; border: 1px solid var(--fail); border-radius: 8px;
  background: color-mix(in srgb, var(--fail) 10%, var(--card)); color: var(--fail); font-weight: 600;
}
.mobile-work-tabs { display: none; }
.code-pane, .result-pane { min-width: 0; }
.code-pane { display: flex; flex-direction: column; gap: 12px; }
.problem-pane[hidden], .code-pane[hidden], .result-pane[hidden] { display: none !important; }
.result-empty {
  padding: 28px 18px; border: 1px dashed var(--border); border-radius: 10px;
  background: var(--card); color: var(--text-2); text-align: center;
}

.progressive-hints {
  margin-top: 20px; padding-top: 16px; border-top: 1px solid var(--border);
}
.progressive-hints h3 { margin: 0 0 10px; }
.hint-level {
  margin: 8px 0; padding: 10px 12px; border-left: 3px solid var(--primary);
  border-radius: 0 7px 7px 0; background: color-mix(in srgb, var(--primary) 7%, var(--card));
}
.hint-level strong { display: block; color: var(--primary); margin-bottom: 3px; }
.progressive-hints .btn { margin: 8px 8px 0 0; }
.independent-redo { color: var(--primary); }

.editor-resize { touch-action: none; user-select: none; }
.editor-resize:focus-visible::after, .editor-resize:active::after { background: var(--primary); }
.editor-retry { box-shadow: 0 2px 8px rgba(0, 0, 0, .16); }

.result-copy {
  align-self: flex-start; flex: 0 0 auto; border: 1px solid var(--border); border-radius: 5px;
  padding: 2px 7px; background: var(--card); color: var(--text-2); cursor: pointer; font-size: 11px;
}
.result-copy:hover { border-color: var(--primary); color: var(--primary); }
.result-long details { flex: 1; min-width: 0; }
.result-long summary {
  cursor: pointer; white-space: pre-wrap; overflow-wrap: anywhere; padding: 5px 8px;
  border-radius: 5px; background: var(--code-bg); font-family: "SF Mono", Menlo, Consolas, monospace;
}
.result-long details[open] summary { margin-bottom: 5px; }
.result-long details pre { width: 100%; }

.mistake-review {
  margin-top: 12px; padding: 12px; border: 1px solid var(--border); border-radius: 8px;
  background: var(--bg);
}
.mistake-review h3 { margin-bottom: 8px; font-size: 14px; }
.mistake-reasons { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 10px; }
.mistake-reason[aria-pressed='true'] { background: var(--primary); color: #fff; border-color: var(--primary); }
.mistake-review label { display: block; color: var(--text-2); margin-bottom: 4px; }
.mistake-review textarea {
  display: block; width: 100%; margin-bottom: 8px; padding: 8px; resize: vertical;
  border: 1px solid var(--border); border-radius: 6px; background: var(--card); color: var(--text);
}
#mistake-save-status { margin-left: 8px; color: var(--pass); }

.data-bar { flex-wrap: wrap; }
.data-bar select {
  border: 1px solid var(--border); border-radius: 7px; padding: 5px 8px;
  background: var(--card); color: var(--text);
}

/* 错题行操作区允许自然换行，编辑区跟所属题目保持视觉关联 */
.mistakes-head + #mistakes-live { min-height: 1.5em; margin: 0 0 8px; }
.pgroup-body > .custom-test { margin: 0 12px 12px 58px; }
.pgroup-body > .plist-row + .custom-test { border-top-left-radius: 0; border-top-right-radius: 0; }
.custom-test form label { display: block; margin-top: 8px; color: var(--text-2); }

@media (min-width: 1200px) {
  .pmain { grid-template-columns: minmax(420px, 0.9fr) minmax(600px, 1.35fr); }
  .results-body { max-height: min(46vh, 520px); }
}

/* 超宽桌面（≥1600px）：题目 | 代码 | 结果 三栏同屏。
   .work 拆解为网格子项（display: contents），结果区 max-height 随视口放宽。
   仅影响 ≥1600px：901–1599px 维持上方两栏布局，≤900px 移动布局不受影响。 */
@media (min-width: 1600px) {
  .pmain { grid-template-columns: minmax(380px, 0.95fr) minmax(520px, 1.2fr) minmax(360px, 0.95fr); }
  .work { display: contents; }
  .results-body { max-height: calc(100vh - 260px); }
}

@media (max-width: 900px) {
  #app { padding: 10px 12px 76px; }
  .topbar { align-items: flex-start; gap: 10px; }
  .topbar .brand { font-size: 16px; }
  .nav { gap: 2px; flex-wrap: wrap; justify-content: flex-end; }
  .nav a { padding: 5px 8px; }
  .stats { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .stat-card { min-width: 0; padding: 11px 12px; }
  .stat-card .num { font-size: 19px; }

  .phead { gap: 8px; }
  .phead h1 { order: 1; width: calc(100% - 60px); }
  .phead .back { order: 0; }
  .phead .head-tags { order: 2; width: 100%; flex-wrap: wrap; }
  .phead .spacer { display: none; }
  .phead .seg { order: 3; flex: 1; }
  .phead .seg button { flex: 1; padding-inline: 9px; }

  .mobile-work-tabs {
    display: flex; position: sticky; top: 0; z-index: 20; margin-bottom: 10px;
    border: 1px solid var(--border); border-radius: 9px; overflow: hidden; background: var(--card);
  }
  .mobile-work-tabs button {
    flex: 1; border: 0; border-right: 1px solid var(--border); padding: 9px;
    background: var(--card); color: var(--text-2); font-weight: 600;
  }
  .mobile-work-tabs button:last-child { border-right: 0; }
  .mobile-work-tabs button.active { background: var(--primary); color: #fff; }
  .pmain { display: block; }
  .work { display: contents; }
  .problem-pane, .code-pane, .result-pane { width: 100%; }
  .result-pane { padding-bottom: calc(72px + env(safe-area-inset-bottom)); scroll-padding-bottom: 72px; }
  .panel-body { max-height: none; }
  #editor-host, .editor-host { height: min(58vh, 560px); }
  .actions { flex-wrap: wrap; }
  .kbd-hint { display: none; }
  .results-body { max-height: none; }
  .case .kv { align-items: flex-start; flex-wrap: wrap; }
  .case .kv .k { width: 58px; }
  .case .kv pre, .result-long details { flex-basis: calc(100% - 70px); }

  .filters { gap: 7px; }
  .filters input[type='search'] { flex-basis: 100%; }
  .filters .seg { order: 5; width: 100%; }
  .filters .seg button { flex: 1; }
  .plist-row { display: grid; grid-template-columns: 24px 34px minmax(0, 1fr) auto; gap: 5px 8px; padding: 10px 11px; }
  .plist-row .status, .plist-row .pid { width: auto; }
  .plist-row .ptitle { grid-column: 3 / 5; }
  .plist-row .mode-badges { grid-column: 3 / 5; flex-wrap: wrap; }
  .plist-row .row-tags { grid-column: 3 / 4; flex-wrap: wrap; min-width: 0; }
  .plist-row .diff { grid-column: 4; grid-row: 3; align-self: start; }
  .mistake-meta { grid-column: 3 / 5; white-space: normal; }
  .plist-row > input[type='checkbox'] { grid-column: 1; grid-row: 1; }
  .plist-row > .btn { grid-column: auto; padding: 5px 8px; }
  .pgroup-body > .custom-test { margin: 0 8px 10px; }
  .data-bar { justify-content: flex-start; }
  .data-tip { flex-basis: 100%; }
  .pnav .btn { max-width: 50%; padding-inline: 10px; }
  /* 知识卡片错题角标是桌面端增强，移动端保持原有布局 */
  .kcard-mistakes { display: none; }
}

@media (max-width: 480px) {
  .stats { grid-template-columns: 1fr; }
  .topbar { display: block; }
  .nav { margin-top: 8px; justify-content: flex-start; }
  .seg { max-width: 100%; }
  .case { padding: 8px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}