/* ============================================================
   🐝 蜜蜂物理 · 动能定理专项精解
   主题：蜂巢黄 + 深炭黑 + 白色卡片
   ============================================================ */
:root {
  --bee-yellow: #FFD600;
  --bee-amber: #FFA000;
  --bee-dark: #1C1C1E;
  --bee-stripe: #FFFDE7;
  --bg: #F5F0E8;
  --text: #1A1A1A;
  --text-sub: #555;
  --text-muted: #888;
  --border: #E8E0C8;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 6px 24px rgba(0,0,0,0.12);
  --radius: 14px;
  --radius-sm: 8px;
  --sidebar-w: 260px;
  --header-h: 60px;
  --tab-h: 64px;
  --t1: #1565C0; --t1-bg: #E3F2FD;
  --t2: #2E7D32; --t2-bg: #E8F5E9;
  --t3: #E65100; --t3-bg: #FFF3E0;
  --t4: #6A1B9A; --t4-bg: #F3E5F5;
  --t5: #00695C; --t5-bg: #E0F2F1;
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── MathJax 行内公式对齐优化 ── */
mjx-container[jax="CHTML"][display="true"] {
  display: block;
  margin: 8px auto;
  overflow-x: auto;
  overflow-y: hidden;
}
mjx-container[jax="CHTML"]:not([display="true"]) {
  display: inline-block;
  vertical-align: middle;
  margin: 0 1px;
  line-height: 1;
}
.problem-statement mjx-container,
.step-row mjx-container,
.killer-step mjx-container,
.killer-tip mjx-container,
.core-tip mjx-container,
.proc-analysis mjx-container,
.option mjx-container {
  vertical-align: -0.2em;
}
html { scroll-behavior: smooth; }
body {
  font-family: 'PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif;
  background: var(--bg); color: var(--text);
  min-height: 100vh; overflow-x: hidden;
}

/* ── Header ── */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--header-h);
  background: var(--bee-dark);
  border-bottom: 3px solid var(--bee-yellow);
  box-shadow: 0 2px 16px rgba(0,0,0,0.4);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 100%; padding: 0 18px;
}
.header-brand { display: flex; align-items: center; gap: 10px; }
.brand-icon { font-size: 26px; }
.brand-title { font-size: 17px; font-weight: 800; color: var(--bee-yellow); letter-spacing: 1px; }
.brand-sub { font-size: 11px; color: #999; margin-top: 1px; }
.menu-btn {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 8px;
}
.menu-btn span { display: block; width: 22px; height: 2px; background: var(--bee-yellow); border-radius: 2px; transition: all .3s; }

/* ── Sidebar ── */
.sidebar {
  position: fixed; top: var(--header-h); left: 0; bottom: 0;
  width: var(--sidebar-w); z-index: 90;
  background: var(--bee-dark); border-right: 1px solid #333;
  overflow-y: auto; transition: transform .3s ease;
}
.sidebar-header {
  padding: 18px 20px 10px;
  font-size: 10px; font-weight: 800; letter-spacing: 2px;
  color: var(--bee-yellow); text-transform: uppercase;
  border-bottom: 1px solid #333;
}
.sidebar-nav { padding: 6px 0; }
.nav-item {
  display: flex; align-items: center; gap: 10px;
  padding: 11px 20px; color: #BBB; text-decoration: none;
  font-size: 13.5px; font-weight: 500;
  border-left: 3px solid transparent; transition: all .2s; cursor: pointer;
}
.nav-item:hover { background: #2A2A2A; color: var(--bee-yellow); }
.nav-item.active { background: #2A2A2A; color: var(--bee-yellow); border-left-color: var(--bee-yellow); font-weight: 700; }
.nav-icon { font-size: 15px; }
.nav-item em { display: block; font-style: normal; font-size: 10px; color: #777; margin-top: 1px; }
.nav-item.active em { color: #BBA000; }
.sidebar-overlay { display: none; position: fixed; inset: 0; z-index: 89; background: rgba(0,0,0,.5); }

/* ── Main ── */
.main-content {
  margin-left: var(--sidebar-w); margin-top: var(--header-h);
  min-height: calc(100vh - var(--header-h));
  padding: 28px 28px 48px; max-width: 900px;
}
.section { display: none; animation: fadeIn .3s ease; }
.section.active { display: block; }
@keyframes fadeIn { from { opacity:0; transform:translateY(6px); } to { opacity:1; transform:none; } }

/* ── Hero ── */
.section-hero {
  background: linear-gradient(135deg, var(--bee-dark) 0%, #2A2000 100%);
  border-radius: var(--radius); padding: 40px 32px; text-align: center;
  margin-bottom: 24px; border: 2px solid var(--bee-yellow);
  position: relative; overflow: hidden;
}
.section-hero::after { content: '🐝'; position: absolute; right: 20px; top: 10px; font-size: 80px; opacity: .07; pointer-events: none; }
.hero-badge { display: inline-block; background: var(--bee-yellow); color: var(--bee-dark); font-size: 11px; font-weight: 800; letter-spacing: 2px; padding: 3px 14px; border-radius: 20px; margin-bottom: 14px; }
.hero-title { font-size: 34px; font-weight: 900; color: var(--bee-yellow); letter-spacing: 4px; margin-bottom: 16px; }
.hero-formula { background: rgba(255,214,0,.1); border: 1px solid rgba(255,214,0,.3); border-radius: 10px; padding: 14px 20px; margin: 14px auto; font-size: 17px; color: white; max-width: 500px; }
.hero-desc { color: #CCC; font-size: 14px; line-height: 1.8; }

/* ── Intro Grid ── */
.intro-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 14px; margin-bottom: 24px; }
.intro-card { background: white; border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); border-top: 3px solid var(--bee-yellow); }
.intro-card-icon { font-size: 22px; margin-bottom: 8px; }
.intro-card h3 { font-size: 13px; font-weight: 700; margin-bottom: 8px; }
.intro-card ul { padding-left: 14px; }
.intro-card li { font-size: 12.5px; color: var(--text-sub); line-height: 1.8; }

/* ── Type Overview ── */
.type-overview h2 { font-size: 15px; font-weight: 800; margin-bottom: 12px; padding-left: 10px; border-left: 4px solid var(--bee-yellow); }
.type-cards-grid { display: grid; grid-template-columns: repeat(5,1fr); gap: 10px; }
.type-overview-card { background: white; border-radius: var(--radius-sm); padding: 14px 8px; text-align: center; cursor: pointer; box-shadow: var(--shadow); border-bottom: 3px solid var(--bee-yellow); transition: transform .2s, box-shadow .2s; }
.type-overview-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.toc-num { display: block; font-size: 20px; font-weight: 900; color: var(--bee-yellow); }
.type-overview-card strong { display: block; font-size: 11px; margin: 5px 0 3px; }
.type-overview-card span { font-size: 10px; color: var(--text-muted); }

/* ── Section Title Bar ── */
.section-title-bar { display: flex; align-items: center; gap: 14px; background: var(--bee-dark); border-radius: var(--radius); padding: 18px 22px; margin-bottom: 18px; border-left: 5px solid var(--bee-yellow); }
.section-num { font-size: 44px; font-weight: 900; color: var(--bee-yellow); line-height: 1; opacity: .9; }
.section-title-bar h2 { font-size: 20px; font-weight: 800; color: white; }
.section-title-bar p { font-size: 12px; color: #AAA; margin-top: 3px; }

/* ── 🐝 秒杀技巧 ── */
.killer-box { background: linear-gradient(135deg, #FFF8E1, #FFFDE7); border: 2px solid var(--bee-amber); border-radius: var(--radius); padding: 18px 20px; margin-bottom: 22px; position: relative; overflow: hidden; }
.killer-box::after { content: '🐝'; position: absolute; right: 14px; top: 8px; font-size: 36px; opacity: .12; pointer-events: none; }
.killer-title { font-size: 14px; font-weight: 800; color: var(--bee-amber); margin-bottom: 12px; }
.killer-step { display: flex; gap: 8px; align-items: flex-start; margin-bottom: 8px; font-size: 13px; line-height: 1.7; }
.ks-num { display: inline-flex; align-items: center; justify-content: center; width: 20px; height: 20px; border-radius: 50%; background: var(--bee-amber); color: white; font-size: 11px; font-weight: 800; flex-shrink: 0; margin-top: 2px; }
.killer-tip { margin-top: 10px; padding: 9px 12px; background: rgba(255,160,0,.12); border-radius: var(--radius-sm); font-size: 12.5px; color: #7A5200; line-height: 1.6; border-left: 3px solid var(--bee-amber); }

/* ── Method Banner ── */
.method-banner { display: flex; align-items: center; gap: 10px; background: var(--bee-stripe); border-radius: var(--radius-sm); padding: 11px 14px; margin-bottom: 18px; border: 1px solid var(--bee-yellow); }
.method-tag { background: var(--bee-yellow); color: var(--bee-dark); font-size: 10px; font-weight: 800; padding: 2px 10px; border-radius: 20px; white-space: nowrap; }
.method-text { font-size: 13px; }

/* ── Problem Card ── */
.problem-card { background: white; border-radius: var(--radius); box-shadow: var(--shadow-lg); margin-bottom: 22px; overflow: hidden; border: 1px solid var(--border); }
.problem-header { padding: 14px 18px 12px; border-bottom: 1px solid #F0EBD8; background: #FAFAF7; }
.problem-meta { display: flex; align-items: center; gap: 8px; margin-bottom: 5px; }
.problem-tag { font-size: 10px; font-weight: 700; padding: 2px 9px; border-radius: 20px; }
.problem-tag.type1 { background: var(--t1-bg); color: var(--t1); }
.problem-tag.type2 { background: var(--t2-bg); color: var(--t2); }
.problem-tag.type3 { background: var(--t3-bg); color: var(--t3); }
.problem-tag.type4 { background: var(--t4-bg); color: var(--t4); }
.problem-tag.type5 { background: var(--t5-bg); color: var(--t5); }
.problem-difficulty { font-size: 12px; color: var(--bee-amber); }
.problem-title { font-size: 15px; font-weight: 700; }
.problem-body { padding: 18px; }
.problem-statement { font-size: 13.5px; line-height: 1.9; margin-bottom: 14px; }

/* ── Options ── */
.options-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 7px; margin: 12px 0; }
.option { padding: 9px 12px; border-radius: var(--radius-sm); background: #F8F8F8; border: 1.5px solid #E0E0E0; font-size: 12.5px; line-height: 1.6; }
.option.correct { background: #E8F5E9; border-color: #2E7D32; color: #1B5E20; font-weight: 600; }
.option.wrong { background: #FFEBEE; border-color: #C62828; color: #B71C1C; }

/* ── Diagram Label ── */
.diagram-label { font-size: 11px; font-weight: 700; color: var(--text-muted); letter-spacing: 1px; margin-bottom: 6px; }

/* ── Steps ── */
.steps-toggle-btn { display: inline-flex; align-items: center; gap: 6px; background: none; border: 1.5px solid var(--bee-amber); color: var(--bee-amber); font-size: 12.5px; font-weight: 600; padding: 7px 16px; border-radius: 20px; cursor: pointer; margin: 14px 0 0; transition: all .2s; }
.steps-toggle-btn:hover { background: var(--bee-amber); color: white; }
.steps-toggle-btn .arr { transition: transform .3s; font-size: 9px; }
.steps-toggle-btn.open .arr { transform: rotate(90deg); }
.steps-content { display: none; border-left: 3px solid var(--bee-amber); padding-left: 14px; margin-top: 10px; margin-bottom: 4px; }
.steps-content.open { display: block; }
.step-row { display: flex; gap: 10px; align-items: flex-start; padding: 8px 0; border-bottom: 1px dashed #F0E8D0; font-size: 13px; line-height: 1.8; }
.step-row:last-child { border-bottom: none; }
.step-lbl { background: var(--bee-dark); color: var(--bee-yellow); font-size: 10px; font-weight: 700; padding: 2px 7px; border-radius: 4px; white-space: nowrap; flex-shrink: 0; margin-top: 3px; }

/* ── Core Tip ── */
.core-tip { display: flex; gap: 8px; align-items: flex-start; background: #FFFDE7; border: 1px solid var(--bee-yellow); border-radius: var(--radius-sm); padding: 10px 14px; margin-top: 10px; font-size: 12.5px; line-height: 1.7; }
.tip-bee { font-size: 18px; flex-shrink: 0; }

/* ════════════ HTML情境图 ════════════ */

/* 例1：两过程对比 */
.two-proc { display: flex; flex-direction: column; background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; overflow: hidden; }
.proc-block { padding: 14px 16px 10px; }
.proc-block + .proc-block { border-top: 1.5px dashed #D0D0D0; }
.proc-badge { display: inline-block; font-size: 10px; font-weight: 800; letter-spacing: 1px; padding: 2px 10px; border-radius: 20px; margin-bottom: 10px; }
.pb1 { background: #E3F2FD; color: #1565C0; }
.pb2 { background: #E8F5E9; color: #2E7D32; }
.force-row { position: relative; height: 68px; }
.fr-ground { position: absolute; bottom: 0; left: 0; right: 0; height: 4px; background: repeating-linear-gradient(-45deg,#777,#777 3px,#ccc 3px,#ccc 9px); border-top: 2px solid #444; }
.fr-block { position: absolute; bottom: 4px; left: 50px; width: 48px; height: 36px; background: #BBDEFB; border: 2px solid #1565C0; border-radius: 4px; display: flex; align-items: center; justify-content: center; font-weight: 700; color: #1565C0; font-size: 13px; }
.fr-pull { position: absolute; bottom: 20px; left: 98px; display: flex; align-items: center; }
.fr-pull-shaft { height: 2.5px; background: #E53935; }
.fr-pull-head { width: 0; height: 0; border-top: 5px solid transparent; border-bottom: 5px solid transparent; border-left: 8px solid #E53935; }
.fr-pull-lbl { font-size: 11px; font-weight: 700; color: #E53935; margin-left: 3px; }
.fr-fric { position: absolute; bottom: 20px; left: 10px; display: flex; align-items: center; }
.fr-fric-head { width: 0; height: 0; border-top: 5px solid transparent; border-bottom: 5px solid transparent; border-right: 8px solid #6A1B9A; }
.fr-fric-shaft { height: 2.5px; background: #6A1B9A; }
.fr-fric-lbl { font-size: 11px; font-weight: 700; color: #6A1B9A; margin-left: 3px; }
.fr-vel { position: absolute; bottom: 20px; right: 8px; display: flex; align-items: center; gap: 3px; }
.fr-vel-shaft { height: 2px; background: #2E7D32; }
.fr-vel-head { width: 0; height: 0; border-top: 4px solid transparent; border-bottom: 4px solid transparent; border-left: 7px solid #2E7D32; }
.fr-vel-lbl { font-size: 12px; font-weight: 700; color: #2E7D32; margin-left: 2px; }
.fr-v0 { position: absolute; top: 2px; left: 50px; font-size: 10px; color: #888; }
.fr-time { position: absolute; top: 2px; right: 8px; font-size: 10px; color: #888; }
.proc-analysis { background: #F8F9FA; border-radius: var(--radius-sm); padding: 10px 14px; margin-top: 10px; font-size: 12.5px; line-height: 1.8; }
.pa-title { font-weight: 800; color: var(--bee-amber); font-size: 11px; margin-bottom: 4px; }
.pa-line { color: var(--text-sub); }
.pa-ans { color: #1565C0; font-weight: 600; }

/* 例2：三辆车 */
.cars-wrap { background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; padding: 16px; }
.car-item { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; }
.car-item:last-of-type { margin-bottom: 0; }
.car-tag { width: 56px; flex-shrink: 0; background: var(--bee-dark); color: var(--bee-yellow); border-radius: 6px; padding: 5px 6px; text-align: center; font-size: 11px; font-weight: 700; line-height: 1.4; }
.car-track { flex: 1; position: relative; height: 28px; }
.car-road { position: absolute; bottom: 0; left: 0; right: 0; height: 3px; background: repeating-linear-gradient(-45deg,#777,#777 3px,#ccc 3px,#ccc 9px); border-top: 1.5px solid #444; }
.car-bar { position: absolute; bottom: 3px; left: 0; height: 20px; border-radius: 3px; display: flex; align-items: center; justify-content: flex-end; padding-right: 5px; font-size: 10px; font-weight: 700; color: white; }
.car-bar.ca { background: #1565C0; width: 85%; }
.car-bar.cb { background: #2E7D32; width: 50%; }
.car-bar.cc { background: #E53935; width: 33%; }
.car-dist { width: 72px; flex-shrink: 0; font-size: 11px; color: var(--text-sub); text-align: right; }
.cars-formula { background: #F3F4F6; border-radius: var(--radius-sm); padding: 9px 12px; margin-top: 10px; font-size: 12.5px; line-height: 1.8; color: var(--text-sub); }
.cars-answer { background: #E8F5E9; border: 1.5px solid #2E7D32; border-radius: var(--radius-sm); padding: 7px 12px; margin-top: 8px; font-size: 14px; font-weight: 700; color: #1B5E20; text-align: center; }

/* 例3：踢皮球 */
.kick-wrap { background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; padding: 16px; }
.kick-top { display: flex; align-items: center; gap: 14px; padding-bottom: 12px; border-bottom: 1.5px dashed #D0D0D0; margin-bottom: 12px; }
.kick-emoji { font-size: 36px; }
.kick-arrow { display: flex; align-items: center; gap: 2px; }
.ka-shaft { height: 2.5px; width: 50px; background: #E53935; }
.ka-head { width: 0; height: 0; border-top: 5px solid transparent; border-bottom: 5px solid transparent; border-left: 8px solid #E53935; }
.kick-vel-lbl { font-size: 12px; font-weight: 700; color: #E53935; margin-left: 4px; }
.kick-ball { font-size: 28px; }
.kick-bottom { position: relative; height: 52px; }
.kick-gnd { position: absolute; bottom: 0; left: 0; right: 0; height: 4px; background: repeating-linear-gradient(-45deg,#777,#777 3px,#ccc 3px,#ccc 9px); border-top: 2px solid #444; }
.kick-ball-roll { position: absolute; bottom: 4px; left: 16px; font-size: 18px; }
.kick-fric { position: absolute; bottom: 16px; left: 50px; display: flex; align-items: center; gap: 2px; font-size: 10px; color: #6A1B9A; font-weight: 700; }
.kf-head { width: 0; height: 0; border-top: 4px solid transparent; border-bottom: 4px solid transparent; border-right: 7px solid #6A1B9A; }
.kf-shaft { height: 2px; width: 28px; background: #6A1B9A; }
.kick-dist { position: absolute; bottom: 6px; left: 50%; transform: translateX(-50%); font-size: 10px; color: #888; }
.kick-stop { position: absolute; bottom: 4px; right: 16px; font-size: 18px; }
.kick-analysis { background: #FFF8E1; border: 1.5px solid var(--bee-amber); border-radius: var(--radius-sm); padding: 10px 12px; margin-top: 10px; font-size: 12.5px; line-height: 1.8; }
.kab-title { font-weight: 800; color: var(--bee-amber); font-size: 11px; margin-bottom: 4px; }
.kab-warn { color: #C62828; font-weight: 600; }
.kab-ans { color: #1565C0; font-weight: 700; }

/* 例4：转台 */
.tt-wrap { display: flex; gap: 18px; align-items: flex-start; background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; padding: 16px; }
.tt-disk-area { flex-shrink: 0; text-align: center; }
.tt-disk { width: 130px; height: 130px; border-radius: 50%; background: radial-gradient(circle, #E3F2FD 60%, #BBDEFB 100%); border: 3px solid #1565C0; position: relative; margin: 0 auto; }
.tt-center-dot { position: absolute; top: 50%; left: 50%; transform: translate(-50%,-50%); width: 10px; height: 10px; background: #1565C0; border-radius: 50%; }
.tt-center-lbl { position: absolute; top: 50%; left: 50%; transform: translate(-50%,-180%); font-size: 11px; font-weight: 700; color: #1565C0; }
.tt-radius { position: absolute; top: 50%; left: 50%; width: 50px; height: 2px; background: #1565C0; transform-origin: left center; transform: rotate(-30deg); }
.tt-block { position: absolute; top: 26%; right: 10%; width: 26px; height: 20px; background: #BBDEFB; border: 2px solid #1565C0; border-radius: 3px; display: flex; align-items: center; justify-content: center; font-size: 10px; font-weight: 700; color: #1565C0; }
.tt-R-lbl { position: absolute; top: 50%; left: 55%; font-size: 11px; font-weight: 700; color: #E53935; transform: translateY(-100%); }
.tt-omega { position: absolute; top: 8px; right: 8px; font-size: 12px; font-weight: 700; color: #6A1B9A; }
.tt-rot { font-size: 26px; color: #1565C0; margin-top: 5px; }
.tt-view-lbl { font-size: 10px; color: #888; margin-top: 3px; }
.tt-analysis { flex: 1; background: #F8F9FA; border-radius: var(--radius-sm); padding: 12px; font-size: 12.5px; line-height: 1.8; }
.tta-title { font-weight: 800; color: var(--bee-amber); font-size: 11px; margin-bottom: 6px; }
.tta-divider { border-top: 1px dashed #D0D0D0; margin: 7px 0; }
.tta-line { color: var(--text-sub); }
.tta-ans { color: #1565C0; font-weight: 700; margin-top: 3px; }

/* 例5：滑草场 */
.ski-wrap { position: relative; width: 100%; height: 210px; background: linear-gradient(180deg,#E3F2FD 0%,#F1F8E9 60%,#E8F5E9 100%); border-radius: var(--radius); overflow: hidden; }
.ski-mountain { position: absolute; bottom: 40px; left: 0; width: 0; height: 0; border-right: 160px solid transparent; border-bottom: 150px solid #8D6E63; }
.ski-slope-a { position: absolute; bottom: 40px; left: 0; width: 110px; height: 2px; background: #5D4037; transform-origin: right bottom; transform: rotate(-54deg); }
.ski-slope-b { position: absolute; bottom: 40px; left: 0; width: 160px; height: 2px; background: #795548; transform-origin: right bottom; transform: rotate(-37deg); }
.ski-pt-A { position: absolute; top: 16px; left: 12px; width: 8px; height: 8px; background: #E53935; border-radius: 50%; }
.ski-lbl-A { position: absolute; top: 6px; left: 6px; font-size: 12px; font-weight: 700; color: #E53935; }
.ski-pt-B { position: absolute; bottom: 40px; left: 104px; width: 7px; height: 7px; background: #1565C0; border-radius: 50%; }
.ski-lbl-B { position: absolute; bottom: 50px; left: 98px; font-size: 11px; font-weight: 700; color: #1565C0; }
.ski-pt-B2 { position: absolute; bottom: 40px; left: 152px; width: 7px; height: 7px; background: #2E7D32; border-radius: 50%; }
.ski-lbl-B2 { position: absolute; bottom: 50px; left: 146px; font-size: 11px; font-weight: 700; color: #2E7D32; }
.ski-ground { position: absolute; bottom: 0; left: 0; right: 0; height: 40px; background: #A5D6A7; border-top: 2px solid #66BB6A; }
.ski-pt-C { position: absolute; bottom: 40px; left: 240px; width: 8px; height: 8px; background: #2E7D32; border-radius: 50%; }
.ski-lbl-C { position: absolute; bottom: 52px; left: 228px; font-size: 11px; font-weight: 700; color: #2E7D32; }
.ski-pt-jia { position: absolute; bottom: 40px; left: 320px; width: 8px; height: 8px; background: #E53935; border-radius: 50%; }
.ski-lbl-jia { position: absolute; bottom: 52px; left: 300px; font-size: 10px; font-weight: 700; color: #E53935; }
.ski-lbl-jia-slope { position: absolute; top: 48px; left: 26px; font-size: 10px; font-weight: 700; color: #E53935; background: rgba(255,255,255,.85); border-radius: 3px; padding: 1px 4px; }
.ski-lbl-yi-slope { position: absolute; top: 72px; left: 60px; font-size: 10px; font-weight: 700; color: #1565C0; background: rgba(255,255,255,.85); border-radius: 3px; padding: 1px 4px; }
.ski-h-line { position: absolute; top: 16px; right: 18px; width: 2px; height: 150px; background: #888; }
.ski-h-lbl { position: absolute; top: 80px; right: 8px; font-size: 12px; font-weight: 700; color: #888; background: rgba(255,255,255,.85); padding: 0 3px; border-radius: 3px; }
.ski-analysis { position: absolute; bottom: 44px; right: 8px; background: rgba(255,255,255,.93); border: 1.5px solid var(--bee-amber); border-radius: 8px; padding: 7px 9px; font-size: 10.5px; line-height: 1.7; max-width: 150px; }
.sab-title { font-weight: 800; color: var(--bee-amber); font-size: 10px; margin-bottom: 3px; }
.sab-ans { color: #1565C0; font-weight: 700; }

/* 例6：拍篮球 */
.bball-wrap { display: flex; gap: 14px; background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; padding: 16px; }
.bball-proc { flex: 1; background: #F8F9FA; border-radius: var(--radius-sm); padding: 12px; text-align: center; }
.bball-title { font-size: 11px; font-weight: 800; color: var(--bee-amber); margin-bottom: 8px; }
.bball-diag { position: relative; height: 130px; }
.bball-top-icon { position: absolute; top: 0; left: 50%; transform: translateX(-50%); font-size: 20px; }
.bball-down-arr { position: absolute; top: 26px; left: 50%; transform: translateX(-50%); font-size: 18px; color: #E53935; }
.bball-h-lbl { position: absolute; top: 40px; right: 8px; font-size: 10px; font-weight: 700; color: #888; writing-mode: vertical-rl; }
.bball-gnd { position: absolute; bottom: 18px; left: 0; right: 0; height: 3px; background: repeating-linear-gradient(-45deg,#777,#777 3px,#ccc 3px,#ccc 9px); border-top: 1.5px solid #444; }
.bball-up-arr { position: absolute; bottom: 21px; left: 50%; transform: translateX(-50%); font-size: 18px; color: #2E7D32; }
.bball-h2-lbl { position: absolute; bottom: 28px; right: 8px; font-size: 10px; font-weight: 700; color: #888; writing-mode: vertical-rl; }
.bball-note { font-size: 10.5px; color: var(--text-sub); line-height: 1.6; margin-top: 6px; text-align: left; }

/* 例7：平抛 */
.proj-wrap { position: relative; width: 100%; height: 190px; background: linear-gradient(180deg,#E3F2FD 0%,#F5F5F5 100%); border-radius: var(--radius); overflow: hidden; }
.proj-cliff { position: absolute; left: 0; top: 0; bottom: 0; width: 55px; background: #8D6E63; border-right: 2px solid #5D4037; }
.proj-cliff-top { position: absolute; top: 28px; left: 0; width: 55px; height: 4px; background: #5D4037; }
.proj-throw-pt { position: absolute; top: 24px; left: 51px; width: 8px; height: 8px; background: #E53935; border-radius: 50%; }
.proj-lbl-throw { position: absolute; top: 14px; left: 57px; font-size: 10px; font-weight: 700; color: #E53935; }
.proj-curve-jia { position: absolute; top: 28px; left: 55px; width: 200px; height: 122px; border: 2px solid #1565C0; border-top: none; border-left: none; border-radius: 0 0 70% 0; }
.proj-curve-yi { position: absolute; top: 28px; left: 55px; width: 110px; height: 122px; border: 2px solid #2E7D32; border-top: none; border-left: none; border-radius: 0 0 70% 0; }
.proj-lbl-jia { position: absolute; top: 58px; left: 185px; font-size: 10px; font-weight: 700; color: #1565C0; background: rgba(255,255,255,.85); padding: 1px 4px; border-radius: 3px; }
.proj-lbl-yi { position: absolute; top: 78px; left: 110px; font-size: 10px; font-weight: 700; color: #2E7D32; background: rgba(255,255,255,.85); padding: 1px 4px; border-radius: 3px; }
.proj-h-line { position: absolute; top: 28px; left: 18px; width: 2px; height: 122px; background: #888; }
.proj-h-lbl { position: absolute; top: 82px; left: 8px; font-size: 12px; font-weight: 700; color: #888; background: rgba(255,255,255,.85); padding: 0 3px; border-radius: 3px; }
.proj-ground { position: absolute; bottom: 0; left: 0; right: 0; height: 30px; background: #A5D6A7; border-top: 2px solid #66BB6A; }
.proj-target { position: absolute; bottom: 30px; right: 24px; font-size: 18px; }
.proj-analysis { position: absolute; top: 8px; right: 8px; background: rgba(255,255,255,.93); border: 1.5px solid var(--bee-amber); border-radius: 8px; padding: 7px 9px; font-size: 10.5px; line-height: 1.7; max-width: 140px; }
.pab-title { font-weight: 800; color: var(--bee-amber); font-size: 10px; margin-bottom: 3px; }
.pab-ans { color: #1565C0; font-weight: 700; }
.pab-wrong { color: #C62828; }

/* 例8：综合大题 */
.comp-wrap { position: relative; width: 100%; height: 190px; background: #F8F9FA; border-radius: var(--radius); overflow: hidden; border: 1.5px solid #E0E0E0; }
.comp-slope-fill { position: absolute; bottom: 55px; left: 16px; width: 0; height: 0; border-right: 100px solid transparent; border-bottom: 75px solid #D7CCC8; }
.comp-slope-line { position: absolute; bottom: 55px; left: 16px; width: 125px; height: 2px; background: #5D4037; transform-origin: right bottom; transform: rotate(-37deg); }
.comp-pt-A { position: absolute; top: 14px; left: 12px; width: 7px; height: 7px; background: #E53935; border-radius: 50%; }
.comp-lbl-A { position: absolute; top: 4px; left: 4px; font-size: 12px; font-weight: 700; color: #E53935; }
.comp-pt-B { position: absolute; bottom: 55px; left: 112px; width: 7px; height: 7px; background: #1565C0; border-radius: 50%; }
.comp-lbl-B { position: absolute; bottom: 65px; left: 104px; font-size: 11px; font-weight: 700; color: #1565C0; }
.comp-arc { position: absolute; bottom: 55px; left: 112px; width: 55px; height: 55px; border: 2px solid #1565C0; border-top: none; border-right: none; border-radius: 0 0 0 100%; }
.comp-pt-C { position: absolute; bottom: 55px; left: 165px; width: 7px; height: 7px; background: #2E7D32; border-radius: 50%; }
.comp-lbl-C { position: absolute; bottom: 65px; left: 157px; font-size: 11px; font-weight: 700; color: #2E7D32; }
.comp-belt-top { position: absolute; bottom: 75px; left: 168px; right: 16px; height: 3px; background: #777; }
.comp-belt-bot { position: absolute; bottom: 55px; left: 168px; right: 16px; height: 3px; background: #777; }
.comp-wheel-l { position: absolute; bottom: 51px; left: 160px; width: 24px; height: 24px; border-radius: 50%; background: #E0E0E0; border: 2px solid #777; display: flex; align-items: center; justify-content: center; font-size: 10px; color: #555; }
.comp-wheel-r { position: absolute; bottom: 51px; right: 12px; width: 24px; height: 24px; border-radius: 50%; background: #E0E0E0; border: 2px solid #777; display: flex; align-items: center; justify-content: center; font-size: 10px; color: #555; }
.comp-belt-arr { position: absolute; bottom: 82px; left: 50%; transform: translateX(-50%); font-size: 10px; color: #555; font-weight: 700; }
.comp-pt-D { position: absolute; bottom: 55px; right: 12px; width: 7px; height: 7px; background: #E53935; border-radius: 50%; }
.comp-lbl-D { position: absolute; bottom: 65px; right: 8px; font-size: 11px; font-weight: 700; color: #E53935; }
.comp-ground { position: absolute; bottom: 0; left: 0; right: 0; height: 55px; background: #ECEFF1; border-top: 2px solid #B0BEC5; }
.comp-H-lbl { position: absolute; top: 14px; right: 8px; font-size: 10px; font-weight: 700; color: #888; }
.comp-theta { position: absolute; bottom: 68px; left: 30px; font-size: 10px; font-weight: 700; color: #5D4037; }
/* comp-params moved to inline param-tags in HTML */

/* 情境图下方分析条 */
.ski-analysis-bar, .proj-analysis-bar {
  background: rgba(255,160,0,.1);
  border: 1.5px solid var(--bee-amber);
  border-radius: var(--radius-sm);
  padding: 8px 12px;
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--text);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}
.sab-title, .pab-title {
  font-weight: 700;
  color: var(--bee-amber);
  flex-shrink: 0;
}
.sab-ans {
  font-weight: 700;
  color: #1565C0;
  margin-left: 6px;
}
.pab-wrong {
  color: #C62828;
  font-weight: 600;
}

/* 例9：W-x图像 */
.wx-wrap { display: flex; gap: 14px; background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; padding: 16px; }
.wx-graph { flex: 1; position: relative; height: 190px; background: white; border: 1.5px solid #E0E0E0; border-radius: var(--radius-sm); }
.wx-graph svg { position: absolute; inset: 0; width: 100%; height: 100%; }
.wx-analysis { width: 200px; flex-shrink: 0; background: #F8F9FA; border-radius: var(--radius-sm); padding: 12px; font-size: 12px; line-height: 2.2; overflow: visible; }
.wxa-title { font-weight: 800; color: var(--bee-amber); font-size: 11px; margin-bottom: 6px; }
.wxa-line { color: var(--text-sub); }
.wxa-ans { color: #1565C0; font-weight: 700; }

/* 例10：传送带 */
.belt-wrap { background: #FAFBFF; border-radius: var(--radius); border: 1.5px solid #E8EAF6; padding: 16px; }
.belt-main { position: relative; height: 90px; background: #F0F4F8; border-radius: var(--radius-sm); overflow: hidden; margin-bottom: 12px; }
.belt-gnd { position: absolute; bottom: 0; left: 0; right: 0; height: 16px; background: #ECEFF1; border-top: 2px solid #B0BEC5; }
.belt-frame { position: absolute; bottom: 16px; left: 36px; right: 36px; height: 26px; border-top: 3px solid #555; border-bottom: 3px solid #555; background: #E0E0E0; }
.belt-wl { position: absolute; bottom: 12px; left: 24px; width: 24px; height: 24px; border-radius: 50%; background: #BDBDBD; border: 2.5px solid #555; display: flex; align-items: center; justify-content: center; font-size: 9px; color: #333; }
.belt-wr { position: absolute; bottom: 12px; right: 24px; width: 24px; height: 24px; border-radius: 50%; background: #BDBDBD; border: 2.5px solid #555; display: flex; align-items: center; justify-content: center; font-size: 9px; color: #333; }
.belt-v-arr { position: absolute; bottom: 48px; left: 50%; transform: translateX(-50%); display: flex; align-items: center; gap: 3px; font-size: 11px; font-weight: 700; color: #1565C0; }
.bva-shaft { width: 36px; height: 2px; background: #1565C0; }
.bva-head { width: 0; height: 0; border-top: 4px solid transparent; border-bottom: 4px solid transparent; border-left: 7px solid #1565C0; }
.belt-lbl-A { position: absolute; bottom: 44px; left: 32px; font-size: 11px; font-weight: 700; color: #333; }
.belt-lbl-B { position: absolute; bottom: 44px; right: 32px; font-size: 11px; font-weight: 700; color: #333; }
.belt-coal { position: absolute; bottom: 42px; left: 70px; width: 26px; height: 20px; background: #37474F; border-radius: 3px; display: flex; align-items: center; justify-content: center; font-size: 9px; color: white; font-weight: 700; }
.belt-trace { position: absolute; bottom: 16px; left: 60px; height: 3px; width: 70px; background: #37474F; opacity: .5; }
.belt-trace-lbl { position: absolute; bottom: 3px; left: 60px; font-size: 9px; color: #555; font-weight: 600; }
.belt-L-lbl { position: absolute; top: 6px; left: 50%; transform: translateX(-50%); font-size: 10px; color: #888; }
.belt-phases { display: flex; gap: 10px; margin-bottom: 10px; }
.belt-ph { flex: 1; border-radius: var(--radius-sm); padding: 10px; font-size: 11.5px; line-height: 1.7; }
.belt-ph.ph1 { background: #FFF3E0; border: 1.5px solid #FFA000; }
.belt-ph.ph2 { background: #E8F5E9; border: 1.5px solid #2E7D32; }
.bph-title { font-weight: 800; font-size: 10px; margin-bottom: 4px; }
.ph1 .bph-title { color: #E65100; }
.ph2 .bph-title { color: #1B5E20; }
.bph-line { color: var(--text-sub); }
.belt-core { background: white; border: 1.5px solid #E0E0E0; border-radius: var(--radius-sm); overflow: hidden; }
.bc-row { display: flex; border-bottom: 1px solid #F0F0F0; }
.bc-row:last-child { border-bottom: none; }
.bc-lbl { width: 110px; flex-shrink: 0; padding: 9px 10px; background: #F8F8F8; font-size: 11px; font-weight: 700; color: #333; border-right: 1px solid #E0E0E0; }
.bc-formula { flex: 1; padding: 9px 10px; font-size: 12.5px; }
.bc-ans { padding: 8px 12px; background: #E8F5E9; font-size: 13px; font-weight: 700; color: #1B5E20; text-align: center; border-top: 1px solid #E0E0E0; }

/* ── Bottom Tab ── */
.bottom-tab { display: none; position: fixed; bottom: 0; left: 0; right: 0; z-index: 100; height: var(--tab-h); background: var(--bee-dark); border-top: 2px solid var(--bee-yellow); padding-bottom: env(safe-area-inset-bottom); }
.bottom-tab-inner { display: flex; height: 100%; }
.tab-btn { flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 2px; background: none; border: none; cursor: pointer; color: #888; transition: color .2s; padding: 4px 0; }
.tab-btn.active { color: var(--bee-yellow); }
.tab-icon { font-size: 17px; line-height: 1; }
.tab-lbl { font-size: 9px; font-weight: 600; }

/* ── Responsive ── */
@media (max-width: 768px) {
  .menu-btn { display: flex; }
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .sidebar-overlay.show { display: block; }
  .main-content { margin-left: 0; padding: 14px 12px calc(var(--tab-h) + 14px); }
  .bottom-tab { display: block; }
  .intro-grid { grid-template-columns: 1fr; }
  .type-cards-grid { grid-template-columns: repeat(3,1fr); }
  .options-grid { grid-template-columns: 1fr; }
  .tt-wrap { flex-direction: column; }
  .bball-wrap { flex-direction: column; }
  .wx-wrap { flex-direction: column; }
  .wx-analysis { width: 100%; }
  .belt-phases { flex-direction: column; }
  .hero-title { font-size: 26px; }
  .section-num { font-size: 36px; }
}
@media (max-width: 480px) {
  .type-cards-grid { grid-template-columns: repeat(2,1fr); }
  .car-dist { display: none; }
}