/* ===========================================================
   公用基础样式 · 全站共用（第 1~5 章 / 练习页 / 点名页）
   · 设计变量 · 布局 · 卡片 · 按钮 · 表格 · 代码块 ……
   · 章节专属样式一律放 css/access_chN.css
   =========================================================== */

/* ---------- 1. 设计变量 ---------- */
:root {
  --bg: #080c1a;
  --bg-soft: #0d1226;
  --panel: rgba(255, 255, 255, .045);
  --panel-2: rgba(255, 255, 255, .07);
  --border: rgba(255, 255, 255, .1);
  --border-strong: rgba(255, 255, 255, .18);
  --text: #e9edfb;
  --text-dim: #c3cbe6;
  --muted: #8f9dc4;
  --brand: #6366f1;
  --brand-2: #22d3ee;
  --accent: #f472b6;
  --ok: #34d399;
  --warn: #fbbf24;
  --danger: #f87171;
  --code-bg: #0a0f22;
  --code-border: rgba(255, 255, 255, .08);
  --shadow: 0 18px 50px rgba(0, 0, 0, .45);
  --shadow-sm: 0 6px 20px rgba(0, 0, 0, .3);
  --radius: 16px;
  --radius-sm: 10px;
  --font: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Source Han Sans SC", "Noto Sans CJK SC", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", "Fira Code", "Cascadia Code", "PingFang SC", Consolas, "Courier New", monospace;
  --grad: linear-gradient(120deg, #6366f1, #22d3ee 55%, #f472b6);

  /* —— 随主题切换的前景色 / 浅底配色（保证白天模式下也能看清）—— */
  --accent-text: #22d3ee;      /* 强调色文字（青） */
  --num-text: #fdba74;         /* 数字 */
  --yes-text: #34d399;         /* 真值 / 通过 */
  --null-text: #94a3b8;        /* 空值 */
  --code-kw: #c7d2fe;          /* 正文中的行内代码文字 */
  --code-kw-bg: rgba(99, 102, 241, .14);
  --pill-fg: #c7d2fe;          /* 徽标文字 */
  --pill-bg: rgba(99, 102, 241, .16);
  /* 数据表视图表头：渐变 + 不透明底色，避免滚动时内容透出来 */
  --ds-head-fg: #e9edfb;
  --ds-head-bg: linear-gradient(180deg, rgba(99, 102, 241, .3), rgba(99, 102, 241, .16)) padding-box;
  --soft-green-fg: #6ee7b7;
  --soft-green-bg: rgba(52, 211, 153, .14);
  --soft-red-fg: #fca5a5;
  --soft-red-bg: rgba(248, 113, 113, .12);
  --soft-cyan-fg: #a5f3fc;
  --soft-pink-fg: #fbcfe8;
  --soft-amber-fg: #fde68a;
}

html[data-theme="light"] {
  --bg: #f4f6fc;
  --bg-soft: #ffffff;
  --panel: rgba(20, 30, 70, .035);
  --panel-2: rgba(20, 30, 70, .06);
  --border: rgba(20, 30, 70, .12);
  --border-strong: rgba(20, 30, 70, .22);
  --text: #121a33;
  --text-dim: #2c3555;
  --muted: #5c688c;
  --code-bg: #0e1531;
  --shadow: 0 18px 44px rgba(30, 42, 90, .14);
  --shadow-sm: 0 6px 18px rgba(30, 42, 90, .1);

  /* —— 白天模式：全部改为深色文字 / 更实的浅底 —— */
  --accent-text: #0e7490;
  --num-text: #a34700;
  --yes-text: #046c4e;
  --null-text: #64748b;
  --code-kw: #312e81;
  --code-kw-bg: rgba(99, 102, 241, .13);
  --pill-fg: #312e81;
  --pill-bg: rgba(99, 102, 241, .13);
  --ds-head-fg: #1e1b4b;
  --ds-head-bg: linear-gradient(180deg, rgba(99, 102, 241, .3), rgba(99, 102, 241, .14)) padding-box;
  --soft-green-fg: #065f46;
  --soft-green-bg: rgba(52, 211, 153, .2);
  --soft-red-fg: #9f1239;
  --soft-red-bg: rgba(248, 113, 113, .16);
  --soft-cyan-fg: #155e75;
  --soft-pink-fg: #9d174d;
  --soft-amber-fg: #854d0e;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 90px; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.85;
  font-size: 15.5px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background:
    radial-gradient(900px 500px at 12% -5%, rgba(99, 102, 241, .18), transparent 60%),
    radial-gradient(800px 500px at 92% 8%, rgba(34, 211, 238, .12), transparent 60%),
    radial-gradient(700px 600px at 50% 100%, rgba(244, 114, 182, .08), transparent 60%);
}

html[data-theme="light"] body::before { opacity: .55; }

a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { line-height: 1.35; margin: 0 0 .6em; font-weight: 700; letter-spacing: .01em; }
p { margin: 0 0 1em; }
code { font-family: var(--mono); font-size: .92em; }
strong { color: #fff; font-weight: 600; }
html[data-theme="light"] strong { color: #0b1330; }
.muted { color: var(--muted); }
.mt { margin-top: 1.6em; }
.mt-sm { margin-top: .7em; }
.hidden { display: none !important; }

::selection { background: rgba(99, 102, 241, .38); }

/* ---------- 2. 顶栏 & 进度条 ---------- */
.scroll-progress {
  position: fixed; top: 0; left: 0; right: 0; height: 3px;
  z-index: 90; background: transparent;
}
.scroll-progress span {
  display: block; height: 100%; width: 0;
  background: var(--grad);
  box-shadow: 0 0 14px rgba(99, 102, 241, .8);
  transition: width .1s linear;
}

.topbar {
  position: sticky; top: 0; z-index: 80;
  display: flex; align-items: center; gap: 18px;
  padding: 12px 26px;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; }
.brand-mark {
  display: grid; place-items: center;
  width: 34px; height: 34px; border-radius: 10px;
  background: var(--grad); color: #fff;
  font-family: var(--mono); font-size: 12.5px; letter-spacing: -.5px;
  box-shadow: 0 6px 18px rgba(99, 102, 241, .45);
}
.brand-text { font-size: 15px; }

.topnav { display: flex; gap: 4px; margin-left: auto; flex-wrap: wrap; }
.topnav a {
  padding: 6px 12px; border-radius: 999px; font-size: 13.5px;
  color: var(--text-dim); transition: .18s;
}
.topnav a:hover { background: var(--panel); color: var(--text); }
.topnav a.active { background: var(--panel-2); color: var(--text); box-shadow: inset 0 0 0 1px var(--border); }
/* 顶栏“SQL 演练场”按钮 */
.nav-btn {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 6px 14px; border-radius: 999px; cursor: pointer;
  font-family: var(--font); font-size: 13.5px; font-weight: 600;
  color: #fff; background: var(--grad); border: 1px solid transparent;
  transition: .18s; box-shadow: 0 6px 16px rgba(99, 102, 241, .32);
}
.nav-btn:hover { transform: translateY(-1px); box-shadow: 0 9px 22px rgba(99, 102, 241, .44); }

.icon-btn {
  width: 36px; height: 36px; border-radius: 10px; cursor: pointer;
  background: var(--panel); border: 1px solid var(--border);
  color: var(--text); font-size: 15px; display: grid; place-items: center;
  transition: .2s; flex: none;
}
.icon-btn:hover { background: var(--panel-2); transform: translateY(-1px); }
html[data-theme="dark"] .t-sun { display: none; }
html[data-theme="light"] .t-moon { display: none; }

/* ---------- 3. 布局 & 目录 ---------- */
.layout {
  position: relative; z-index: 1;
  display: grid; grid-template-columns: 250px minmax(0, 1fr);
  gap: 40px; max-width: 1500px; margin: 0 auto; padding: 0 26px;
  transition: grid-template-columns .3s ease, gap .3s ease;
}

.sidebar { position: relative; }
.toc {
  position: sticky; top: 82px; padding: 20px 0 30px;
  max-height: calc(100vh - 100px); overflow-y: auto;
}
.toc-title { margin: 0 0 10px; font-size: 12px; letter-spacing: .16em; color: var(--muted); text-transform: uppercase; }
.toc-link {
  display: block; padding: 6px 12px; margin: 1px 0;
  border-left: 2px solid var(--border);
  color: var(--muted); font-size: 13.5px; line-height: 1.6;
  transition: .18s;
}
.toc-link.lv2 { padding-left: 24px; font-size: 13px; }
.toc-link:hover { color: var(--text); border-left-color: var(--border-strong); }
.toc-link.active {
  color: var(--text); border-left-color: var(--brand);
  background: linear-gradient(90deg, rgba(99, 102, 241, .16), transparent);
  font-weight: 600;
}
/* 目录里的“SQL 演练场”按钮（去掉边框，只保留文字强调与背景） */
.toc-link.open-lab {
  display: block; width: 100%; cursor: pointer; text-align: left;
  font-family: var(--font); font-weight: 700; font-size: 13.5px;
  color: var(--brand-2); border: 0; border-left: 0; box-shadow: none;
  background: linear-gradient(90deg, rgba(99, 102, 241, .14), transparent);
}
.toc-link.open-lab:hover { color: #fff; background: rgba(99, 102, 241, .3); }
html[data-theme="light"] .toc-link.open-lab { color: var(--accent-text); }
html[data-theme="light"] .toc-link.open-lab:hover { color: var(--text); }
.toc-meter { margin-top: 14px; height: 3px; background: var(--border); border-radius: 3px; overflow: hidden; }
.toc-meter span { display: block; height: 100%; width: 0; background: var(--grad); transition: width .2s; }

/* 目录折叠 / 展开按钮 */
.toc-toggle {
  display: flex; align-items: center; justify-content: center; gap: 7px;
  width: 100%; padding: 9px 12px; margin-bottom: 12px;
  border: 1px solid var(--border); border-radius: 12px;
  background: var(--panel); color: var(--text-dim);
  font-family: var(--font); font-size: 13px; font-weight: 600; cursor: pointer;
  transition: .2s;
}
.toc-toggle:hover { color: var(--text); border-color: var(--border-strong); background: var(--panel-2); }
.toc-toggle .tt-closed { display: none; }
.toc-toggle .tt-open { display: inline-flex; align-items: center; gap: 7px; }

/* 折叠状态：目录隐藏，左侧只留一个竖排「☰ 目录」小把手 */
.layout.side-closed { grid-template-columns: 44px minmax(0, 1fr); gap: 14px; }
.layout.side-closed .toc { display: none; }
.layout.side-closed .toc-toggle {
  width: 40px; min-height: 130px; padding: 12px 4px; margin: 0 auto;
  display: block; text-align: center;
  writing-mode: vertical-rl; text-orientation: upright; letter-spacing: .3em;
  border-radius: 12px; position: sticky; top: 82px;
}
.layout.side-closed .toc-toggle .tt-open { display: none; }
.layout.side-closed .toc-toggle .tt-closed { display: block; }

/* ---------- 4. HERO ---------- */
.hero {
  position: relative;
  margin: 26px 0 10px;
  padding: 74px 46px 66px;
  border-radius: 26px;
  overflow: hidden;
  border: 1px solid var(--border);
  background: linear-gradient(150deg, rgba(99, 102, 241, .16), rgba(34, 211, 238, .08) 45%, rgba(244, 114, 182, .12));
  box-shadow: var(--shadow);
}
.hero-bg { position: absolute; inset: 0; overflow: hidden; }
.orb { position: absolute; border-radius: 50%; filter: blur(60px); opacity: .55; animation: float 16s ease-in-out infinite; }
.orb1 { width: 380px; height: 380px; background: #6366f1; top: -120px; left: -60px; }
.orb2 { width: 340px; height: 340px; background: #22d3ee; bottom: -140px; right: 6%; animation-delay: -5s; }
.orb3 { width: 300px; height: 300px; background: #f472b6; top: 20%; right: -110px; animation-delay: -9s; }
.grid-lines {
  position: absolute; inset: 0;
  background-image: linear-gradient(rgba(255, 255, 255, .05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, .05) 1px, transparent 1px);
  background-size: 46px 46px;
  mask-image: radial-gradient(ellipse at 60% 40%, #000 20%, transparent 78%);
}
@keyframes float {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(26px, -22px) scale(1.08); }
}

/* 正文最大 700px。≥1250px 漂浮卡出现时，正文自动让出右侧 300px 走廊
   （min() 不支持的旧浏览器会沿用上面的 700px 回退值） */
.hero-inner { position: relative; z-index: 2; max-width: 700px; }
@media (min-width: 1250px) {
  .hero-inner { max-width: min(700px, calc(100% - 300px)); }
}
.hero-eyebrow {
  display: inline-block; margin: 0 0 18px; padding: 5px 14px;
  border: 1px solid var(--border-strong); border-radius: 999px;
  font-size: 12.5px; letter-spacing: .04em; color: var(--text-dim);
  background: rgba(255, 255, 255, .05); backdrop-filter: blur(6px);
}
.hero-title { font-size: clamp(30px, 4.4vw, 52px); margin-bottom: .5em; letter-spacing: .01em; }
.hero-dot { margin: 0 .35em; color: var(--muted); }
.grad {
  background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-lead { font-size: 16.5px; color: var(--text-dim); max-width: 760px; }

.hero-chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0 26px; }
.chip {
  padding: 5px 13px; border-radius: 999px; font-size: 12.5px;
  border: 1px solid var(--border-strong); color: var(--text-dim);
  background: rgba(255, 255, 255, .04);
}
.hero-btns { display: flex; gap: 12px; flex-wrap: wrap; }

.btn {
  display: inline-flex; align-items: center; gap: 8px; cursor: pointer;
  padding: 9px 18px; border-radius: 11px; font-size: 14px; font-weight: 600;
  border: 1px solid var(--border-strong); background: var(--panel);
  color: var(--text); transition: .2s; font-family: var(--font);
}
.btn:hover { transform: translateY(-2px); }
.btn.lg { padding: 12px 24px; font-size: 15px; }
.btn.sm { padding: 6px 13px; font-size: 13px; border-radius: 9px; }
.btn.primary {
  background: var(--grad); color: #fff; border-color: transparent;
  box-shadow: 0 10px 26px rgba(99, 102, 241, .38);
}
.btn.primary:hover { box-shadow: 0 14px 32px rgba(99, 102, 241, .5); }
.btn.ghost:hover { background: var(--panel-2); }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none; }
.btn kbd {
  font-family: var(--mono); font-size: 10.5px; padding: 1px 5px; border-radius: 5px;
  background: rgba(0, 0, 0, .28); border: 1px solid rgba(255, 255, 255, .2);
}

/* 漂浮代码卡：贴 hero 右缘，≥1250px 屏幕显示 */
.float-cards {
  position: absolute; top: 0; right: 0; bottom: 0;
  width: 300px; z-index: 1; pointer-events: none;
}
.float-card {
  position: absolute; padding: 10px 16px; border-radius: 12px;
  background: rgba(10, 15, 34, .72); border: 1px solid var(--border-strong);
  color: #a5b4fc; font-size: 13px; box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px); animation: bob 9s ease-in-out infinite;
  white-space: nowrap;
}
.float-card code { color: #c7d2fe; }
/* 四张卡贴 hero 右缘排布（最靠左的 fc4 距右缘 56px） */
.fc1 { top: 15%; right: 16px; animation-delay: 0s; }
.fc2 { top: 39%; right: 44px; animation-delay: -2.4s; }
.fc3 { bottom: 17%; right: 8px; animation-delay: -4.8s; }
.fc4 { bottom: 35%; right: 56px; animation-delay: -7.2s; }
@keyframes bob {
  0%, 100% { transform: translateY(0) rotate(-1.5deg); }
  50% { transform: translateY(-16px) rotate(1.5deg); }
}

.hero-scroll {
  position: absolute; bottom: 18px; left: 50%; transform: translateX(-50%);
  font-size: 12px; color: var(--muted); letter-spacing: .2em; z-index: 2;
  animation: blink 2.4s ease-in-out infinite;
}
@keyframes blink { 0%, 100% { opacity: .35; } 50% { opacity: 1; } }

/* ---------- 5. 章节 & 正文 ---------- */
.section { padding: 56px 0 20px; scroll-margin-top: 80px; }
.sec-head { margin-bottom: 30px; }
/* 编号徽标与标题同行、与标题文字等高：用 flex 对齐 */
.sec-head { display: flex; flex-wrap: wrap; align-items: center; gap: 14px; }
.sec-head .sec-sub { flex-basis: 100%; }   /* 副标题独占一行，排在标题下方 */
.sec-num {
  display: inline-block; padding: 6px 18px; border-radius: 999px;
  font-family: var(--mono); font-size: 20px; letter-spacing: .06em; font-weight: 700;
  line-height: 1.4;
  color: var(--pill-fg); background: var(--pill-bg);
  border: 1px solid rgba(99, 102, 241, .3);
  white-space: nowrap;
}
.sec-head h2 { font-size: clamp(23px, 2.6vw, 32px); margin: 0; }
.sec-sub { color: var(--muted); max-width: 820px; margin: 0; }

.block { padding-top: 26px; margin-top: 26px; border-top: 1px dashed var(--border); }
.block h3 { font-size: 21px; }
.block h3::before {
  content: ""; display: inline-block; width: 4px; height: 18px;
  margin-right: 10px; border-radius: 3px; background: var(--grad);
  vertical-align: -3px;
}
.block h4 { font-size: 16.5px; margin-top: 1.6em; color: var(--text); }
main p { color: var(--text-dim); }

.quote {
  margin-top: 26px; padding: 20px 24px; border-radius: var(--radius);
  border-left: 3px solid var(--brand);
  background: linear-gradient(90deg, rgba(99, 102, 241, .12), transparent);
  font-size: 15.5px;
}
.quote p { margin: 0; color: var(--text); }

.goal-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; }
.goal-card {
  padding: 22px; border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--panel); transition: .25s;
}
.goal-card:hover { transform: translateY(-4px); border-color: var(--border-strong); box-shadow: var(--shadow-sm); }
.goal-icon {
  width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
  background: var(--grad); color: #fff; font-weight: 700; margin-bottom: 12px;
}
.goal-card h3 { font-size: 16px; }
.goal-card p { margin: 0; font-size: 14px; color: var(--muted); }

/* ---------- 6. 代码块 ---------- */
.code {
  position: relative; margin: 16px 0; border-radius: var(--radius-sm);
  border: 1px solid var(--code-border); background: var(--code-bg);
  overflow: hidden; box-shadow: var(--shadow-sm);
}
html[data-theme="light"] .code { --code-bg: #0e1531; }
.code-head {
  display: flex; align-items: center; gap: 10px; padding: 8px 12px;
  background: rgba(255, 255, 255, .035); border-bottom: 1px solid var(--code-border);
}
.code-dots { display: flex; gap: 5px; }
.code-dots i { width: 10px; height: 10px; border-radius: 50%; background: rgba(255, 255, 255, .18); }
.code-dots i:nth-child(1) { background: #ff5f57; }
.code-dots i:nth-child(2) { background: #febc2e; }
.code-dots i:nth-child(3) { background: #28c840; }
.code-title { font-size: 12px; color: #94a3c8; font-family: var(--mono); letter-spacing: .02em; }
.code-tools { margin-left: auto; display: flex; gap: 6px; }
.code-btn {
  padding: 3px 10px; font-size: 11.5px; border-radius: 6px; cursor: pointer;
  background: rgba(255, 255, 255, .07); border: 1px solid rgba(255, 255, 255, .12);
  color: #cbd5e1; transition: .18s; font-family: var(--font);
}
.code-btn:hover { background: rgba(255, 255, 255, .16); color: #fff; }
.code-btn.ok { background: rgba(52, 211, 153, .22); border-color: rgba(52, 211, 153, .4); color: #6ee7b7; }

.code-body { display: flex; }
.code-gutter {
  padding: 14px 10px 14px 14px; text-align: right; user-select: none;
  font-family: var(--mono); font-size: 13px; line-height: 1.75;
  color: #46507a; background: rgba(0, 0, 0, .22); border-right: 1px solid var(--code-border);
}
.code pre {
  margin: 0; padding: 14px 16px; overflow-x: auto;
  font-family: var(--mono); font-size: 13px; line-height: 1.75;
  color: #dbe3ff; flex: 1;
}
.code.big pre { font-size: 13.5px; padding: 18px; }
.code.compact { margin: 10px 0; }
.code.compact pre { padding: 10px 14px; font-size: 12.5px; }
.code.plain .code-head { background: rgba(255, 255, 255, .02); }

/* SQL 语法高亮 */
.tk-kw { color: #7dd3fc; font-weight: 600; }
.tk-fn { color: #f0abfc; }
.tk-str { color: #86efac; }
.tk-num { color: #fdba74; }
.tk-date { color: #fcd34d; }
.tk-op { color: #94a3c8; }
.tk-punc { color: #64748b; }
.tk-com { color: #64748b; font-style: italic; }
.tk-id { color: #e2e8ff; }

/* ---------- 7. 教材截图 ---------- */
.fig-row { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.figure { margin: 20px 0; }
.fig-frame {
  /* 白底卡片恰好包裹图片：fit-content 收缩到图片宽度，再整体居中 */
  width: fit-content; max-width: 100%;
  margin: 0 auto;
  position: relative; border-radius: 12px; overflow: hidden;
  border: 1px solid var(--border); background: #fff;   /* 白底衬托浅色 Access 截图 */
  box-shadow: var(--shadow-sm);
}
.fig-frame img {
  display: block; max-width: 100%; height: auto; width: auto;
  /* 小图（图 5-5、5-6）不放大，避免模糊；宽图缩放至容器宽 */
}
.fig-cap { margin-top: 8px; font-size: 12.5px; color: var(--muted); text-align: center; }

/* ---------- 8. 时间线 ---------- */
.timeline { position: relative; margin: 24px 0; padding-left: 22px; }
.timeline::before {
  content: ""; position: absolute; left: 6px; top: 6px; bottom: 6px; width: 2px;
  background: linear-gradient(180deg, var(--brand), var(--brand-2), var(--accent));
  opacity: .5;
}
.tl-item { position: relative; margin-bottom: 14px; }
.tl-dot {
  position: absolute; left: -22px; top: 12px; width: 14px; height: 14px; border-radius: 50%;
  background: var(--bg); border: 3px solid var(--brand); box-shadow: 0 0 0 4px rgba(99, 102, 241, .15);
}
.tl-card {
  padding: 14px 18px; border-radius: var(--radius-sm);
  background: var(--panel); border: 1px solid var(--border); transition: .2s;
}
.tl-card:hover { border-color: var(--border-strong); transform: translateX(4px); }
.tl-year { font-family: var(--mono); font-size: 12.5px; color: var(--accent-text); letter-spacing: .04em; font-weight: 600; }
.tl-card p { margin: 4px 0 0; font-size: 14px; }

/* ---------- 9. 四大分类卡片 ---------- */
.cat-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; margin: 22px 0; }
.cat-card { perspective: 1200px; height: 190px; cursor: pointer; outline: none; }
.cat-inner {
  position: relative; width: 100%; height: 100%;
  transition: transform .65s cubic-bezier(.4, .2, .2, 1);
  transform-style: preserve-3d;
}
.cat-card:hover .cat-inner, .cat-card:focus .cat-inner, .cat-card.flipped .cat-inner { transform: rotateY(180deg); }
.cat-front, .cat-back {
  position: absolute; inset: 0; backface-visibility: hidden;
  padding: 20px; border-radius: var(--radius);
  border: 1px solid var(--border); background: var(--bg-soft);
  box-shadow: var(--shadow-sm); display: flex; flex-direction: column;
}
.cat-front { align-items: flex-start; }
.cat-front::before {
  content: ""; position: absolute; inset: 0; border-radius: var(--radius);
  background: radial-gradient(120px 80px at 100% 0, color-mix(in srgb, var(--c) 28%, transparent), transparent 70%);
}
.cat-abbr {
  font-family: var(--mono); font-size: 26px; font-weight: 700; color: var(--c);
  letter-spacing: .04em;
}
.cat-front h4 { margin: 6px 0 4px; font-size: 16px; }
.cat-kw {
  font-family: var(--mono); font-size: 11.5px; color: var(--muted);
  padding: 3px 9px; border-radius: 6px; background: rgba(255, 255, 255, .05);
  border: 1px solid var(--border);
}
.cat-more { margin-top: auto; font-size: 12px; color: var(--muted); }
.cat-back { transform: rotateY(180deg); background: linear-gradient(160deg, var(--bg-soft), color-mix(in srgb, var(--c) 12%, var(--bg-soft))); }
.cat-back h4 { font-size: 14px; color: var(--c); }
/* 白天模式：青/绿/黄等亮色在白底上对比度不足，混一点深色压下去 */
html[data-theme="light"] .cat-abbr,
html[data-theme="light"] .cat-back h4,
html[data-theme="light"] .ddl-kw { color: color-mix(in srgb, var(--c) 58%, #0b1024); }
.cat-back p { font-size: 13.5px; color: var(--text-dim); }
.cat-badge {
  margin-top: auto; align-self: flex-start; padding: 4px 12px; border-radius: 999px;
  font-size: 12px; border: 1px solid;
}
.cat-badge.ok { color: var(--soft-green-fg); border-color: rgba(52, 211, 153, .45); background: var(--soft-green-bg); }
.cat-badge.no { color: var(--soft-red-fg); border-color: rgba(248, 113, 113, .45); background: var(--soft-red-bg); }

/* ---------- 10. 选项卡 / 分段控件 ---------- */
.tabs { margin: 18px 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--panel); overflow: hidden; }
.tab-strip { display: flex; gap: 4px; padding: 8px; border-bottom: 1px solid var(--border); flex-wrap: wrap; }
.tab-btn {
  padding: 7px 15px; border-radius: 9px; cursor: pointer; font-size: 13.5px;
  background: transparent; border: 1px solid transparent; color: var(--muted);
  transition: .18s; font-family: var(--font);
}
.tab-btn:hover { color: var(--text); background: var(--panel-2); }
.tab-btn.active {
  color: #fff; background: var(--grad); border-color: transparent;
  box-shadow: 0 6px 18px rgba(99, 102, 241, .3);
}
html[data-theme="light"] .tab-btn.active { color: #fff; }
.tab-panels { padding: 18px 20px; }
.tab-panel p:last-child { margin-bottom: 0; }

.seg {
  display: inline-flex; gap: 3px; padding: 3px; border-radius: 11px;
  background: var(--panel-2); border: 1px solid var(--border);
}
.seg-btn {
  padding: 6px 14px; border-radius: 8px; cursor: pointer; font-size: 13px;
  background: transparent; border: 0; color: var(--muted); transition: .18s; font-family: var(--font);
}
.seg-btn:hover { color: var(--text); }
.seg-btn.active { background: var(--grad); color: #fff; box-shadow: 0 4px 14px rgba(99, 102, 241, .35); }
.seg.sm .seg-btn { padding: 4px 11px; font-size: 12.5px; }

/* ---------- 11. 表格 ---------- */
.table-wrap { margin: 20px 0; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; background: var(--panel); }
.table-cap { padding: 12px 18px; font-size: 13.5px; font-weight: 600; border-bottom: 1px solid var(--border); background: rgba(255, 255, 255, .03); }
.data-table { width: 100%; border-collapse: collapse; font-size: 13.5px; }
.data-table th {
  padding: 10px 16px; text-align: left; font-weight: 600; font-size: 12.5px;
  color: var(--muted); background: rgba(255, 255, 255, .02);
  border-bottom: 1px solid var(--border); letter-spacing: .04em;
}
.data-table td { padding: 10px 16px; border-bottom: 1px solid var(--border); color: var(--text-dim); }
.data-table tbody tr:last-child td { border-bottom: 0; }
.data-table tbody tr:hover td { background: rgba(99, 102, 241, .07); }
.data-table code {
  padding: 2px 7px; border-radius: 6px; background: var(--code-kw-bg);
  color: var(--code-kw); font-size: 12.5px;
}
.fn-table td:nth-child(odd) { width: 30%; }

/* 结果表（数据表视图风格） */
.datasheet { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: auto; max-height: 420px; background: var(--bg-soft); }
.datasheet table { border-collapse: collapse; width: 100%; font-size: 13px; font-family: var(--mono); }
.datasheet thead th {
  position: sticky; top: 0; z-index: 2; white-space: nowrap;
  padding: 8px 14px; text-align: left; font-weight: 600;
  background: var(--ds-head-bg), var(--bg-soft);
  border-bottom: 1px solid var(--border-strong); border-right: 1px solid var(--border);
  color: var(--ds-head-fg); font-family: var(--font); font-size: 12.5px;
}
.datasheet tbody td {
  padding: 6px 14px; border-bottom: 1px solid var(--border); border-right: 1px solid var(--border);
  white-space: nowrap; color: var(--text-dim);
}
.datasheet tbody tr:nth-child(even) td { background: rgba(99, 102, 241, .05); }
.datasheet tbody tr:hover td { background: rgba(99, 102, 241, .13); }
.datasheet td.num { text-align: right; color: var(--num-text); }
.datasheet td.null { color: var(--null-text); font-style: italic; }
.datasheet td.bool { text-align: center; }
.datasheet .b-yes { color: var(--yes-text); }
.datasheet .b-no { color: var(--null-text); }
.datasheet-wrap { margin-top: 14px; }
.ds-info { display: flex; gap: 14px; flex-wrap: wrap; align-items: center; margin-bottom: 8px; font-size: 12.5px; color: var(--muted); }
.ds-info b { color: var(--accent-text); font-family: var(--mono); }

/* ---------- 12. 提示条 ---------- */
.callout {
  display: flex; gap: 14px; margin: 18px 0; padding: 14px 18px;
  border-radius: var(--radius-sm); border: 1px solid var(--border);
  background: var(--panel); border-left: 3px solid var(--brand);
}
.callout.inline { margin: 12px 0; }
.callout p { margin: 0; font-size: 14px; }
.callout p + p { margin-top: 8px; }
.co-icon {
  flex: none; width: 22px; height: 22px; border-radius: 50%; display: grid; place-items: center;
  font-size: 12px; font-weight: 700; background: var(--brand); color: #fff;
}
.callout.tip { border-left-color: var(--brand-2); }
.callout.tip .co-icon { background: var(--brand-2); color: #062a33; }
.callout.note { border-left-color: var(--brand); }
.callout.warn { border-left-color: var(--warn); background: rgba(251, 191, 36, .07); }
.callout.warn .co-icon { background: var(--warn); color: #3a2a05; }
.callout.danger { border-left-color: var(--danger); background: rgba(248, 113, 113, .08); }
.callout.danger .co-icon { background: var(--danger); color: #3a0d0d; }
.callout code { padding: 1px 6px; border-radius: 5px; background: var(--code-kw-bg); color: var(--code-kw); }

/* ---------- 13. 例题卡片 & 列表 ---------- */
.ex-card {
  position: relative; margin: 22px 0; padding: 22px 24px 20px;
  border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--panel); box-shadow: var(--shadow-sm);
}
.ex-card::before {
  content: ""; position: absolute; left: 0; top: 18px; bottom: 18px; width: 3px;
  border-radius: 0 3px 3px 0; background: var(--grad);
}
.ex-tag {
  display: inline-block; margin-bottom: 10px; padding: 3px 12px; border-radius: 999px;
  font-size: 12px; font-weight: 700; letter-spacing: .05em;
  background: var(--grad); color: #fff;
}
.ex-body > p:first-of-type { margin-top: 0; }

.point-list { margin: 14px 0; padding: 0; list-style: none; }
.point-list li {
  position: relative; padding: 8px 0 8px 26px; font-size: 14.5px; color: var(--text-dim);
  border-bottom: 1px dashed var(--border);
}
.point-list li:last-child { border-bottom: 0; }
.point-list li::before {
  content: "▸"; position: absolute; left: 6px; color: var(--accent-text);
}
.point-list b { color: var(--text); }
.point-list code { padding: 1px 6px; border-radius: 5px; background: var(--code-kw-bg); color: var(--code-kw); }

.split { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.split > div { min-width: 0; }

.op-table { display: grid; gap: 10px; margin: 18px 0; }
.op-row {
  display: grid; grid-template-columns: 90px 1fr 1.4fr; gap: 16px; align-items: center;
  padding: 12px 16px; border-radius: var(--radius-sm);
  background: var(--panel); border: 1px solid var(--border); transition: .2s;
}
.op-row:hover { border-color: var(--border-strong); background: var(--panel-2); }
.op-name code { font-size: 15px; color: var(--accent-text); font-weight: 600; }
.op-fmt code { font-size: 12.5px; color: var(--code-kw); }
.op-desc { font-size: 13.5px; color: var(--text-dim); }

.steps-list { list-style: none; margin: 16px 0; padding: 0; }
.steps-list li { display: flex; gap: 14px; padding: 12px 0; border-bottom: 1px dashed var(--border); }
.steps-list li:last-child { border-bottom: 0; }
.steps-list span {
  flex: none; width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  background: var(--grad); color: #fff; font-size: 13px; font-weight: 700;
}
.steps-list p { margin: 0; font-size: 14px; color: var(--muted); }

.ddl-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 14px; margin: 20px 0; }
.ddl-card {
  padding: 18px 20px; border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--panel); transition: .25s;
  border-top: 3px solid var(--c);
}
.ddl-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-sm); }
.ddl-kw { font-family: var(--mono); font-size: 14px; font-weight: 700; color: var(--c); }
.ddl-card p { margin: 4px 0 0; font-size: 13.5px; color: var(--muted); }

/* ---------- 14. 子句图解 ---------- */
.clause-box {
  margin: 22px 0; border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--panel); overflow: hidden;
}
.clause-sql {
  display: flex; flex-wrap: wrap; gap: 8px; padding: 16px;
  border-bottom: 1px solid var(--border); background: rgba(0, 0, 0, .18);
}
.clause {
  display: flex; align-items: baseline; gap: 7px; cursor: pointer;
  padding: 7px 14px; border-radius: 9px; font-family: var(--mono); font-size: 13px;
  background: rgba(255, 255, 255, .05); border: 1px solid var(--border); color: var(--text-dim);
  transition: .2s;
}
.clause em { font-style: normal; font-size: 11.5px; color: var(--muted); font-family: var(--font); }
.clause:hover { transform: translateY(-2px); border-color: var(--border-strong); }
.clause.active {
  background: var(--grad); color: #fff; border-color: transparent;
  box-shadow: 0 8px 22px rgba(99, 102, 241, .35);
}
.clause.active em { color: rgba(255, 255, 255, .85); }
.clause-panels { padding: 18px 20px; }
.clause-panel h4 { margin: 0 0 6px; font-size: 15px; }
.clause-panel p { margin: 0; font-size: 14px; color: var(--text-dim); }
.clause-panel code { padding: 1px 6px; border-radius: 5px; background: var(--code-kw-bg); color: var(--code-kw); }

/* ---------- 15. 交互实验区通用 ---------- */
.lab-card, .mini-lab {
  margin: 22px 0; border: 1px solid var(--border); border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(99, 102, 241, .07), var(--panel));
  overflow: hidden; box-shadow: var(--shadow-sm);
}
.lab-head, .mini-head {
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
  padding: 12px 16px; border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, .03);
}
.lab-actions { margin-left: auto; display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.lab-body, .mini-body { padding: 16px; }
.lab-foot, .mini-foot {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  padding: 10px 16px; border-top: 1px solid var(--border);
  font-size: 12.5px; color: var(--muted); background: rgba(0, 0, 0, .14);
}
.lab-hint { color: var(--muted); }
.mini-title { font-size: 13.5px; font-weight: 600; }
.mini-actions { margin-left: auto; display: flex; gap: 8px; }
.mini-lab.big .mini-body { padding: 18px; }
.lab-result, .mini-result { padding: 0 16px 16px; }
.lab-result:empty { padding: 0; }
.mini-sql {
  margin-left: auto; font-family: var(--mono); font-size: 12.5px; color: var(--accent-text);
  padding: 4px 10px; border-radius: 7px; background: var(--code-kw-bg);
  border: 1px solid rgba(99, 102, 241, .28); font-weight: 600;
}
.inline-field { display: inline-flex; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); }
.inline-field select, .builder select {
  padding: 5px 10px; border-radius: 8px; font-size: 13px; font-family: var(--font);
  background: var(--bg-soft); color: var(--text); border: 1px solid var(--border-strong);
  cursor: pointer;
}

/* QBE 设计网格 */
.qbe { overflow-x: auto; }
.qbe table { border-collapse: collapse; width: 100%; font-size: 13px; font-family: var(--mono); }
.qbe th, .qbe td {
  border: 1px solid var(--border-strong); padding: 7px 12px; text-align: center;
  min-width: 110px; background: rgba(255, 255, 255, .02);
}
.qbe thead th { background: rgba(99, 102, 241, .2); font-family: var(--font); font-size: 12.5px; white-space: nowrap; }
.qbe tbody th {
  background: rgba(99, 102, 241, .1); font-family: var(--font); font-size: 12.5px;
  text-align: left; white-space: nowrap; width: 74px; color: var(--text-dim);
}
.qbe .cell-cond { background: var(--soft-green-bg); color: var(--soft-green-fg); font-weight: 600; transition: .3s; }
.qbe .cell-show { color: var(--yes-text); }
.qbe .cell-plain { color: var(--muted); }

/* 排序演示 */
.sort-table { width: 100%; border-collapse: collapse; font-size: 13px; font-family: var(--mono); }
.sort-table th {
  cursor: pointer; padding: 8px 12px; text-align: left; white-space: nowrap;
  background: rgba(99, 102, 241, .16); border-bottom: 1px solid var(--border-strong);
  font-family: var(--font); font-size: 12.5px; transition: .2s; user-select: none;
}
.sort-table th:hover { background: rgba(99, 102, 241, .32); }
.sort-table th .arrow { color: var(--accent-text); margin-left: 6px; font-weight: 600; }
.sort-table td { padding: 6px 12px; border-bottom: 1px solid var(--border); color: var(--text-dim); }
.sort-table tbody tr:hover td { background: rgba(99, 102, 241, .09); }

/* 分组流水线 */
.flow { display: grid; gap: 8px; }
.flow-step {
  display: flex; gap: 12px; padding: 10px 12px; border-radius: var(--radius-sm);
  background: var(--panel); border: 1px solid var(--border);
}
.flow-step.dim { opacity: .4; }
.fs-tag {
  flex: none; width: 84px; font-family: var(--mono); font-size: 11.5px; font-weight: 600;
  padding: 3px 0; text-align: center; border-radius: 6px; height: fit-content;
  background: var(--pill-bg); color: var(--pill-fg); border: 1px solid rgba(99, 102, 241, .3);
}
.fs-body { flex: 1; min-width: 0; font-size: 13px; color: var(--text-dim); }
.fs-body .chipset { display: flex; flex-wrap: wrap; gap: 5px; }
.gchip {
  padding: 2px 9px; border-radius: 999px; font-size: 11.5px; font-family: var(--mono);
  background: rgba(255, 255, 255, .06); border: 1px solid var(--border); color: var(--text-dim);
}
.gchip.g { background: var(--soft-green-bg); border-color: rgba(52, 211, 153, .4); color: var(--soft-green-fg); }
.gchip.drop { opacity: .35; text-decoration: line-through; }
.flow-arrow { text-align: center; color: var(--muted); font-size: 14px; line-height: 1; }

/* 嵌套查询 */
.nest-steps { display: grid; gap: 12px; }
.nest-step {
  display: flex; gap: 12px; padding: 12px; border-radius: var(--radius-sm);
  border: 1px dashed var(--border); opacity: .45; transition: .35s;
}
.nest-step.active { opacity: 1; border-style: solid; border-color: var(--brand); background: rgba(99, 102, 241, .08); }
.ns-badge {
  flex: none; width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  background: var(--grad); color: #fff; font-size: 13px; font-weight: 700;
}
.ns-main { flex: 1; min-width: 0; }
.ns-result { margin-top: 8px; }

/* Any / All */
.qt-desc { font-size: 13.5px; color: var(--text-dim); margin: 0 0 10px; }
.quant-result { margin-top: 12px; }
.scoreline { margin: 6px 0 14px; }
.sl-title { font-size: 12px; color: var(--muted); margin-bottom: 6px; }
.sl-track {
  position: relative; height: 30px; border-radius: 8px;
  background: linear-gradient(90deg, rgba(248, 113, 113, .18), rgba(251, 191, 36, .18), rgba(52, 211, 153, .18));
  border: 1px solid var(--border);
}
.sl-dot {
  position: absolute; top: 50%; width: 10px; height: 10px; margin: -5px 0 0 -5px;
  border-radius: 50%; background: #64748b; transition: .3s;
}
.sl-dot.hit { background: var(--ok); box-shadow: 0 0 0 3px rgba(52, 211, 153, .25); transform: scale(1.3); }
.sl-scale { display: flex; justify-content: space-between; font-size: 10.5px; color: var(--muted); font-family: var(--mono); }

/* 多表连接图 */
.join-graph { display: flex; align-items: stretch; gap: 6px; flex-wrap: wrap; }
.jt {
  flex: 1 1 190px; border: 1px solid var(--border); border-radius: var(--radius-sm);
  background: var(--bg-soft); overflow: hidden; transition: .25s;
}
.jt.hot { border-color: var(--brand); box-shadow: 0 0 0 2px rgba(99, 102, 241, .18); }
.jt-head {
  padding: 7px 12px; font-size: 13px; font-weight: 600;
  background: linear-gradient(90deg, rgba(99, 102, 241, .22), transparent);
  border-bottom: 1px solid var(--border);
}
.jt-alias { font-family: var(--mono); font-size: 11px; color: var(--accent-text); font-weight: 600; }
.jt-cols { list-style: none; margin: 0; padding: 6px 0; }
.jt-cols li { padding: 3px 14px; font-size: 12.5px; font-family: var(--mono); color: var(--muted); transition: .2s; }
.jt-cols li.key::before { content: "🔑 "; font-size: 10px; }
.jt-cols li.on { background: rgba(99, 102, 241, .22); color: var(--text); font-weight: 600; }
.jc { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 6px; min-width: 120px; }
.jc code {
  font-size: 11.5px; padding: 4px 8px; border-radius: 7px; color: var(--code-kw);
  background: var(--code-kw-bg); border: 1px solid rgba(99, 102, 241, .3);
  transition: .2s; cursor: default; white-space: nowrap;
}
.jc.hot code { background: var(--grad); color: #fff; border-color: transparent; }
.jc-line { width: 46px; height: 2px; background: linear-gradient(90deg, var(--brand), var(--brand-2)); opacity: .6; }
.join-result { margin-top: 14px; }

/* UNION 合并 */
.union-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.ucol { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; background: var(--bg-soft); }
.ucol-head {
  padding: 7px 12px; font-size: 12.5px; font-weight: 600; color: var(--text-dim);
  background: rgba(99, 102, 241, .14); border-bottom: 1px solid var(--border);
}
.ucol-body { padding: 8px; display: flex; flex-wrap: wrap; gap: 5px; max-height: 180px; overflow-y: auto; }
.uchip {
  padding: 3px 9px; border-radius: 7px; font-size: 11.5px; font-family: var(--mono);
  background: rgba(255, 255, 255, .06); border: 1px solid var(--border); color: var(--text-dim);
  transition: .3s;
}
.uchip.a { border-color: rgba(34, 211, 238, .45); color: var(--soft-cyan-fg); }
.uchip.b { border-color: rgba(244, 114, 182, .45); color: var(--soft-pink-fg); }
.uchip.dup { border-color: rgba(251, 191, 36, .55); background: rgba(251, 191, 36, .16); color: var(--soft-amber-fg); }
.uchip.pop { animation: pop .35s ease; }
@keyframes pop { 0% { transform: scale(.6); opacity: 0; } 60% { transform: scale(1.1); } 100% { transform: scale(1); opacity: 1; } }
.union-merge { margin-top: 14px; }
.um-arrow { text-align: center; color: var(--muted); font-size: 12.5px; margin-bottom: 6px; }
.ucol-count { float: right; font-family: var(--mono); font-size: 11.5px; color: var(--accent-text); font-weight: 600; }

/* 建表器 */
.builder { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.builder-fields { display: grid; gap: 8px; align-content: start; }
.bf {
  display: grid; grid-template-columns: 22px 1fr 140px 108px; gap: 10px; align-items: center;
  padding: 9px 12px; border-radius: var(--radius-sm);
  background: var(--panel); border: 1px solid var(--border); transition: .2s;
}
.bf:hover { border-color: var(--border-strong); }
.bf input[type="checkbox"] { width: 16px; height: 16px; accent-color: var(--brand); cursor: pointer; }
.bf-name { font-family: var(--mono); font-size: 13px; }
.bf.off { opacity: .45; }
.bf-note { font-size: 11.5px; color: var(--muted); }
.builder-preview { margin-top: 12px; }
.bpv { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; }
.bpv-head { padding: 7px 12px; font-size: 12.5px; background: rgba(99, 102, 241, .16); border-bottom: 1px solid var(--border); }
.bpv table { width: 100%; border-collapse: collapse; font-size: 12.5px; font-family: var(--mono); }
.bpv td { padding: 6px 12px; border-bottom: 1px solid var(--border); color: var(--text-dim); }
.bpv td:last-child { color: var(--muted); font-size: 11.5px; }
.bpv tr:last-child td { border-bottom: 0; }

/* 数据操纵演示 */
.dml-body { min-height: 260px; }
.dml-callout {
  padding: 10px 14px; margin: 10px 0 14px; border-radius: var(--radius-sm);
  background: rgba(251, 191, 36, .08); border: 1px solid rgba(251, 191, 36, .25);
  font-size: 13px; color: var(--text-dim);
}
.dml-tables { display: grid; grid-template-columns: 1fr auto 1fr; gap: 12px; align-items: center; }
.dt-col { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; background: var(--bg-soft); }
.dt-head { padding: 6px 12px; font-size: 12.5px; background: rgba(99, 102, 241, .14); border-bottom: 1px solid var(--border); }
.dt-body { padding: 8px; font-family: var(--mono); font-size: 12px; }
.dt-body table { width: 100%; border-collapse: collapse; }
.dt-body td { padding: 4px 8px; border-bottom: 1px solid var(--border); color: var(--text-dim); white-space: nowrap; }
.dt-body tr:last-child td { border-bottom: 0; }
.dt-body tr.row-new td { background: var(--soft-green-bg); color: var(--soft-green-fg); font-weight: 600; animation: slideIn .45s ease; }
.dt-body tr.row-hit td { background: rgba(251, 191, 36, .18); color: var(--soft-amber-fg); font-weight: 600; }
.dt-body tr.row-gone { opacity: .3; text-decoration: line-through; }
.dt-body td.changed { background: rgba(52, 211, 153, .28); color: var(--soft-green-fg); border-radius: 4px; font-weight: 600; }
@keyframes slideIn { from { transform: translateX(-14px); opacity: 0; } to { transform: none; opacity: 1; } }
.dt-arrow { font-size: 12.5px; color: var(--muted); text-align: center; white-space: nowrap; transition: .3s; }
.dt-arrow.on { color: var(--yes-text); font-weight: 700; }
.dml-note { font-size: 12.5px; color: var(--muted); margin-left: auto; }

/* ---------- 15.5 SQL 演练场 · 弹出窗口 ---------- */
body.modal-open { overflow: hidden; }

.modal-overlay {
  position: fixed; inset: 0; z-index: 120;
  display: flex; align-items: center; justify-content: center; padding: 22px;
  background: rgba(5, 8, 20, .66); backdrop-filter: blur(6px);
  animation: fadeIn .22s ease;
}
/* 关键：作者样式 display:flex 会覆盖 HTML 的 hidden 属性（UA 默认 display:none 优先级更低），
   必须用更高优先级的选择器显式关闭，否则弹窗一进页面就显示且无法关闭 */
.modal-overlay[hidden] { display: none !important; }
html[data-theme="light"] .modal-overlay { background: rgba(30, 42, 90, .4); }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

.modal {
  width: min(1160px, 100%); max-height: calc(100vh - 44px);
  display: flex; flex-direction: column; overflow: hidden;
  border: 1px solid var(--border-strong); border-radius: 18px;
  background: var(--bg); box-shadow: 0 30px 80px rgba(0, 0, 0, .55);
  animation: slideUp .28s cubic-bezier(.2, .8, .3, 1);
}
@keyframes slideUp { from { transform: translateY(26px); opacity: 0; } to { transform: none; opacity: 1; } }

.modal-head {
  display: flex; align-items: center; justify-content: space-between; gap: 14px;
  padding: 14px 18px; border-bottom: 1px solid var(--border);
  background: linear-gradient(90deg, rgba(99, 102, 241, .14), transparent);
}
.modal-title { display: flex; align-items: center; gap: 12px; }
.brand-mark.small { width: 38px; height: 38px; font-size: 12px; flex: none; }
.modal-title h3 { margin: 0; font-size: 17px; }
.modal-title p { margin: 0; font-size: 12px; color: var(--muted); }
.modal-close {
  flex: none; width: 34px; height: 34px; border-radius: 10px; cursor: pointer;
  background: var(--panel); border: 1px solid var(--border-strong);
  color: var(--text-dim); font-size: 15px; transition: .18s;
}
.modal-close:hover { background: var(--danger); color: #fff; border-color: transparent; }

.modal .playground {
  overflow: auto; flex: 1; min-height: 0;
  border: 0; border-radius: 0; box-shadow: none;
}
.modal .editor textarea { height: 150px; }
.modal .result { min-height: 90px; }
.modal-foot {
  padding: 10px 18px; border-top: 1px solid var(--border);
  background: rgba(0, 0, 0, .14); font-size: 12.5px; color: var(--muted);
}

/* ---------- 16. 演练场 ---------- */
.playground {
  display: grid; grid-template-columns: minmax(0, 1fr) 280px; gap: 18px;
  border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--bg-soft); overflow: hidden; box-shadow: var(--shadow);
}
.pg-main { display: flex; flex-direction: column; min-width: 0; }
.pg-toolbar {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 10px 14px; border-bottom: 1px solid var(--border);
  background: linear-gradient(90deg, rgba(99, 102, 241, .16), transparent);
}
.pg-title { font-size: 12.5px; color: var(--text-dim); font-family: var(--mono); display: flex; align-items: center; gap: 6px; }
.pg-title .dot-r, .pg-title .dot-y, .pg-title .dot-g { width: 10px; height: 10px; border-radius: 50%; display: inline-block; }
.pg-title .dot-r { background: #ff5f57; } .pg-title .dot-y { background: #febc2e; } .pg-title .dot-g { background: #28c840; }
.pg-actions { margin-left: auto; display: flex; gap: 8px; flex-wrap: wrap; }

.editor { display: flex; background: var(--code-bg); border-bottom: 1px solid var(--border); }
.gutter {
  padding: 14px 10px 14px 14px; text-align: right; user-select: none;
  font-family: var(--mono); font-size: 13px; line-height: 1.75; color: #46507a;
  background: rgba(0, 0, 0, .25); border-right: 1px solid var(--border); min-width: 44px;
}
.editor-wrap { position: relative; flex: 1; min-width: 0; }
.editor-wrap pre, .editor-wrap textarea {
  margin: 0; padding: 14px 16px; border: 0;
  font-family: var(--mono); font-size: 13px; line-height: 1.75;
  white-space: pre; overflow: auto; tab-size: 2;
}
.editor-wrap pre { position: absolute; inset: 0; pointer-events: none; color: #dbe3ff; background: transparent; }
.editor-wrap textarea {
  position: relative; display: block; width: 100%; height: 190px; resize: vertical;
  background: transparent; color: transparent; caret-color: #22d3ee; outline: none;
}
.editor-wrap textarea::placeholder { color: #46507a; }
.editor-wrap textarea::selection { background: rgba(99, 102, 241, .4); }

.ex-chips { display: flex; gap: 6px; padding: 10px 14px; overflow-x: auto; border-bottom: 1px solid var(--border); }
.ex-chip {
  flex: none; padding: 4px 11px; border-radius: 999px; cursor: pointer; font-size: 12px;
  background: rgba(255, 255, 255, .05); border: 1px solid var(--border); color: var(--text-dim);
  transition: .18s; font-family: var(--font); white-space: nowrap;
}
.ex-chip:hover { background: rgba(99, 102, 241, .2); color: #fff; border-color: var(--brand); transform: translateY(-1px); }

.pg-status { padding: 0 14px; font-size: 13px; }
/* 提示条也会出现在演练场之外的演示区，因此不限定在 .pg-status 内 */
.msg { padding: 8px 12px; border-radius: 8px; margin: 10px 0 0; font-size: 13px; }
.msg.err {
  background: var(--soft-red-bg); border: 1px solid rgba(248, 113, 113, .4); color: var(--soft-red-fg);
  font-family: var(--mono); font-size: 12.5px;
}
.msg.ok {
  background: var(--soft-green-bg); border: 1px solid rgba(52, 211, 153, .4); color: var(--soft-green-fg);
}
.result { padding: 14px; min-height: 120px; }
.result-empty { color: var(--muted); font-size: 13.5px; text-align: center; padding: 30px 0; }

.pg-side { border-left: 1px solid var(--border); padding: 16px; background: rgba(255, 255, 255, .02); }
.side-title { margin: 0 0 10px; font-size: 13px; letter-spacing: .06em; color: var(--muted); text-transform: uppercase; }
.db-panel { list-style: none; margin: 0 0 16px; padding: 0; }
.db-panel li {
  display: flex; align-items: center; gap: 8px; padding: 7px 10px; margin-bottom: 5px;
  border-radius: 8px; cursor: pointer; font-size: 13px; color: var(--text-dim);
  border: 1px solid var(--border); background: var(--panel); transition: .18s;
}
.db-panel li:hover { border-color: var(--brand); background: rgba(99, 102, 241, .12); transform: translateX(2px); }
.db-panel .tb-name { font-family: var(--mono); }
.db-panel .tb-count { margin-left: auto; font-size: 11.5px; color: var(--muted); font-family: var(--mono); }
.db-panel .tb-new { animation: pop .4s ease; border-color: var(--ok); }
.side-tip { font-size: 12.5px; color: var(--muted); }
.side-tip p { margin: 0 0 8px; }
.side-tip strong { color: var(--text-dim); font-size: 12.5px; }

/* ---------- 17. 测验 ---------- */
.quiz { border: 1px solid var(--border); border-radius: var(--radius); background: var(--panel); overflow: hidden; }
.q-item { padding: 18px 20px; border-bottom: 1px solid var(--border); }
.q-item:last-child { border-bottom: 0; }
.q-text { font-size: 14.5px; margin-bottom: 12px; font-weight: 600; }
.q-num { color: var(--accent-text); font-family: var(--mono); margin-right: 8px; font-weight: 700; }
.q-opts { display: grid; gap: 8px; }
.q-opt {
  display: flex; gap: 10px; align-items: flex-start; padding: 10px 14px; cursor: pointer;
  border-radius: var(--radius-sm); border: 1px solid var(--border);
  background: var(--bg-soft); font-size: 13.5px; color: var(--text-dim); transition: .18s;
}
.q-opt:hover { border-color: var(--border-strong); background: var(--panel-2); }
.q-opt .qk { font-family: var(--mono); color: var(--muted); flex: none; }
.q-opt.picked { border-color: var(--brand); background: rgba(99, 102, 241, .12); }
.q-opt.right { border-color: var(--ok); background: var(--soft-green-bg); color: var(--soft-green-fg); font-weight: 600; }
.q-opt.wrong { border-color: var(--danger); background: var(--soft-red-bg); color: var(--soft-red-fg); font-weight: 600; }
.q-exp { margin-top: 10px; font-size: 13px; color: var(--muted); display: none; }
.q-exp.show { display: block; animation: slideIn .3s ease; }
.q-foot {
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
  padding: 16px 20px; background: rgba(0, 0, 0, .16); border-top: 1px solid var(--border);
}
.q-score { font-size: 15px; }
.q-score b { font-family: var(--mono); font-size: 22px; color: var(--accent-text); }

/* ---------- 18. 页脚 & 其他 ---------- */
.footer { padding: 40px 0 60px; text-align: center; color: var(--muted); font-size: 13px; }
.footer p { margin: 4px 0; }

.to-top {
  position: fixed; right: 22px; bottom: 22px; z-index: 70;
  width: 42px; height: 42px; border-radius: 50%; cursor: pointer;
  border: 1px solid var(--border-strong); background: var(--bg-soft);
  color: var(--text); font-size: 17px; box-shadow: var(--shadow-sm);
  opacity: 0; pointer-events: none; transition: .25s;
}
.to-top.show { opacity: 1; pointer-events: auto; }
.to-top:hover { transform: translateY(-3px); background: var(--brand); color: #fff; }

/* 滚动出现动画 */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity .6s ease, transform .6s cubic-bezier(.2, .7, .3, 1); }
.reveal.in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .orb, .float-card, .hero-scroll { animation: none; }
}

/* ---------- 19. 响应式 ---------- */
/* 漂浮卡：宽度 <1250px 时隐藏（正文占满整行），≥1250px 出现在右侧走廊 */
@media (max-width: 1249px) {
  .float-cards { display: none; }
}
@media (max-width: 1180px) {
  .layout { grid-template-columns: 1fr; gap: 0; }
  .sidebar { display: none; }
  .topnav { display: none; }
  .playground { grid-template-columns: 1fr; }
  .pg-side { border-left: 0; border-top: 1px solid var(--border); }
}
@media (max-width: 820px) {
  body { font-size: 15px; }
  .hero { padding: 46px 22px 44px; }
  .fig-row, .split, .builder, .union-cols, .dml-tables { grid-template-columns: 1fr; }
  .op-row { grid-template-columns: 1fr; gap: 4px; }
  .dml-tables .dt-arrow { transform: rotate(90deg); }
  .bf { grid-template-columns: 22px 1fr; }
  .bf select { grid-column: 2; }
  .layout { padding: 0 16px; }
  .cat-card { height: 210px; }
}