/* ==========================================================================
   星龙学院 · 官网样式表
   设计基调：AI 科技风 / 深色为默认，可切换浅色 / 留白充足 / 动效克制

   主题机制：
     - 默认（无 data-theme 或 data-theme="dark"）为深色科技风
     - [data-theme="light"] 覆盖全部颜色变量，切到浅色
     - 所有颜色（含半透明、渐变、光晕）一律走变量，禁止在组件里硬编码色值，
       否则切换到浅色时会出现"深色残片"
   ========================================================================== */

:root {
  /* ---------- 深色（默认主题） ---------- */

  /* 底色（由深到浅，逐层抬升） */
  --bg: #05070e;
  --bg-soft: #0a0f1c;
  --bg-raised: #0e1526;
  --bg-deep: #03050b;
  --surface: #0d1424;
  --surface-2: #121a2e;
  --surface-3: #17203a;

  /* 文字（浅色，保证对比度） */
  --ink: #eef3fb;
  --ink-2: #b3c0d6;
  --ink-3: #7d8ba3;
  --ink-4: #56637a;

  /* 品牌色：电光青 + 深空蓝 */
  --brand: #22d3ee;
  --brand-600: #06b6d4;
  --brand-400: #67e8f9;
  --brand-050: rgba(34, 211, 238, 0.12);
  --accent: #8b5cf6;
  --accent-050: rgba(139, 92, 246, 0.14);
  --accent-ink: #c4b5fd;

  /* 边框（半透明白，深色下才自然） */
  --line: rgba(148, 178, 220, 0.16);
  --line-soft: rgba(148, 178, 220, 0.09);

  /* 形状 */
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 14px 40px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 30px 80px rgba(0, 0, 0, 0.6);
  --glow: 0 0 0 1px rgba(34, 211, 238, 0.25), 0 0 34px rgba(34, 211, 238, 0.16);

  /* 信号色 */
  --danger: #f87171;
  --danger-ink: #fca5a5;
  --danger-050: rgba(248, 113, 113, 0.12);
  --danger-035: rgba(248, 113, 113, 0.35);
  --danger-line: rgba(248, 113, 113, 0.7);
  --success: #34d399;
  --success-ink: #6ee7b7;
  --success-050: rgba(52, 211, 153, 0.12);
  --success-035: rgba(52, 211, 153, 0.32);

  /* 品牌半透明衍生（描边 / 悬停 / 高亮） */
  --brand-line: rgba(34, 211, 238, 0.3);
  --brand-line-strong: rgba(34, 211, 238, 0.35);
  --brand-line-hover: rgba(34, 211, 238, 0.4);
  --brand-line-focus: rgba(34, 211, 238, 0.55);
  --brand-line-focus-2: rgba(34, 211, 238, 0.6);
  --brand-hover-050: rgba(34, 211, 238, 0.1);
  --brand-row-hover: rgba(34, 211, 238, 0.045);
  --brand-shadow-sm: rgba(34, 211, 238, 0.24);
  --brand-shadow-md: rgba(34, 211, 238, 0.36);
  --brand-glow: rgba(34, 211, 238, 0.16);
  --accent-line: rgba(139, 92, 246, 0.35);
  --accent-hover-050: rgba(139, 92, 246, 0.2);

  /* 中性半透明衍生 */
  --neutral-050: rgba(148, 178, 220, 0.1);
  --neutral-035: rgba(148, 178, 220, 0.05);
  --selected-bg: rgba(34, 211, 238, 0.28);
  --selected-ink: #ffffff;
  --selection-ink: #ffffff;
  --grid-line: rgba(148, 178, 220, 0.035);
  --scrollbar-track: var(--bg-deep);
  --scrollbar-thumb: #22304a;
  --scrollbar-thumb-hover: #2f4162;

  /* 表面 / 遮罩 / 控件（深色下多为"深色半透明"） */
  --header-bg: rgba(5, 7, 14, 0.78);
  --header-bg-scrolled: rgba(5, 7, 14, 0.94);
  --header-shadow: 0 6px 30px rgba(0, 0, 0, 0.5);
  --nav-sheet-bg: rgba(6, 10, 20, 0.98);
  --panel-bg: linear-gradient(160deg, rgba(19, 27, 48, 0.92) 0%, rgba(10, 15, 28, 0.92) 100%);
  --card-bg: linear-gradient(165deg, var(--surface-2) 0%, var(--surface) 100%);
  --modal-bg: linear-gradient(170deg, var(--surface-2) 0%, var(--surface) 100%);
  --input-bg: rgba(6, 11, 22, 0.7);
  --input-bg-focus: rgba(9, 16, 30, 0.9);
  --subtle-bg: rgba(6, 11, 22, 0.7);
  --subtle-bg-2: rgba(6, 11, 22, 0.65);
  --overlay: rgba(2, 4, 10, 0.72);
  --cover-bg: linear-gradient(140deg, #10203c 0%, #0a1526 55%, #141a3a 100%);
  --cover-ink: rgba(238, 243, 251, 0.9);
  --tag-bg: rgba(8, 14, 26, 0.85);
  --cta-bg: linear-gradient(120deg, #0c2138 0%, #0b2540 45%, #17244f 100%);
  --cta-ink: #ffffff;
  --cta-lead: rgba(238, 243, 251, 0.72);
  --cta-line: rgba(34, 211, 238, 0.22);
  --footer-ink: rgba(179, 192, 214, 0.78);
  --skeleton-1: #101a2c;
  --skeleton-2: #17233a;
  --avatar-bg: linear-gradient(140deg, rgba(34, 211, 238, 0.22), rgba(139, 92, 246, 0.22));
  --avatar-bg-lg: linear-gradient(140deg, rgba(34, 211, 238, 0.24), rgba(139, 92, 246, 0.24));
  --avatar-shadow: 0 8px 26px rgba(0, 0, 0, 0.35);
  --mark-ink: #04121b;
  --mark-shadow: 0 4px 16px rgba(34, 211, 238, 0.3);
  --on-brand: #04121b;
  --ghost-bg: rgba(148, 178, 220, 0.05);
  --light-btn-bg: #f1f5f9;
  --light-btn-bg-hover: #ffffff;
  --light-btn-ink: #0b1220;
  --outline-light-bg: rgba(255, 255, 255, 0.05);
  --outline-light-ink: #eef3fb;
  --outline-light-line: rgba(255, 255, 255, 0.28);
  --ring: rgba(34, 211, 238, 0.14);

  /* 渐变文字（三档色标） */
  --grad-a: var(--brand);
  --grad-b: #60a5fa;
  --grad-c: var(--accent);
  --grad-hero-a: var(--brand);
  --grad-hero-b: #60a5fa;
  --grad-hero-c: var(--accent);
  --grad-stat-a: var(--brand);
  --grad-stat-b: #60a5fa;
  --mark-grad: linear-gradient(140deg, var(--brand-600) 0%, #4f7df3 55%, var(--accent) 100%);
  --btn-primary-grad: linear-gradient(120deg, var(--brand-600) 0%, var(--brand) 60%, #5eead4 100%);
  --timeline-grad: linear-gradient(180deg, rgba(34, 211, 238, 0.5), rgba(139, 92, 246, 0.3), transparent);
  --hairline-grad: linear-gradient(90deg, transparent, rgba(34, 211, 238, 0.5), transparent);
  --card-glow: radial-gradient(circle, rgba(34, 211, 238, 0.22), transparent 68%);
  --halo-a: radial-gradient(1000px 520px at 78% -12%, rgba(34, 211, 238, 0.13), transparent 62%);
  --halo-b: radial-gradient(760px 480px at 6% 4%, rgba(139, 92, 246, 0.1), transparent 64%);
  --hero-halo-a: radial-gradient(900px 420px at 82% -8%, rgba(34, 211, 238, 0.14), transparent 60%);
  --hero-halo-b: radial-gradient(700px 380px at 8% 104%, rgba(139, 92, 246, 0.12), transparent 62%);
  --cover-halo: radial-gradient(400px 200px at 78% -20%, rgba(34, 211, 238, 0.28), transparent 62%);
  --cta-halo: radial-gradient(600px 320px at 88% -30%, rgba(34, 211, 238, 0.24), transparent 62%);

  /* 明暗切换按钮图标所依赖的变量（浅色下需反转） */
  --icon-sun: #fbbf24;
  --icon-moon: #a5b4fd;

  /* 云端降级提示（深色主题） */
  --degrade-bg: linear-gradient(160deg, #101a30 0%, #0c1424 100%);
  --degrade-line: rgba(34, 211, 238, 0.22);
  --degrade-icon-bg: rgba(34, 211, 238, 0.12);
  --degrade-icon-ink: #22d3ee;
  --degrade-title-ink: #eef3fb;
  --degrade-text-ink: #b3c0d6;
  --degrade-notice-bg: rgba(34, 211, 238, 0.1);
  --degrade-notice-line: rgba(34, 211, 238, 0.28);
  --degrade-notice-ink: #67e8f9;
  --degrade-notice-text: #c7d5e8;
  --degrade-dot: #22d3ee;

  /* ---------- 课程中心（列表 / 详情）----------
     深色底上 категория 色块用低透明铺底 + 亮色文字，保证在深空底上不刺眼 */
  --cat1: #22d3ee;
  --cat1-050: rgba(34, 211, 238, 0.14);
  --cat2: #8b5cf6;
  --cat2-050: rgba(139, 92, 246, 0.16);
  --cat3: #34d399;
  --cat3-050: rgba(52, 211, 153, 0.14);
  --cat4: #f59e0b;
  --cat4-050: rgba(245, 158, 11, 0.15);
  --cat5: #f472b6;
  --cat5-050: rgba(244, 114, 182, 0.15);

  --cat-ink: #eef3fb;
  --cat-band-line: rgba(148, 178, 220, 0.2);
  --ccard-bg: var(--surface);
  --ccard-hover-line: var(--brand-line-hover);
  --chip-bg: var(--surface-2);
  --chip-ink: var(--ink-2);
  --chip-line: var(--line);
  --outline-num-bg: var(--surface-2);
  --outline-num-ink: var(--brand);
  --outline-num-line: var(--line);
  --crumb-ink: var(--ink-3);
  --crumb-cur-ink: var(--ink);
  --badge-bg: var(--surface-2);
  --badge-ink: var(--ink-2);
  --badge-line: var(--line);

  --maxw: 1200px;
  --header-h: 72px;

  --font: "Inter", system-ui, -apple-system, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

/* ==========================================================================
   浅色主题：只覆盖颜色变量，结构与间距完全复用
   基调：瓷白底 + 学院蓝，保留科技感但转为"日光版"
   ========================================================================== */

[data-theme="light"] {
  /* 底色 */
  --bg: #f6f8fc;
  --bg-soft: #eef2f9;
  --bg-raised: #ffffff;
  --bg-deep: #ffffff;
  --surface: #ffffff;
  --surface-2: #f7f9fd;
  --surface-3: #eaeff8;

  /* 文字（深色，保证对比度） */
  --ink: #0d1526;
  --ink-2: #4a5568;
  --ink-3: #6b7789;
  --ink-4: #9aa4b4;

  /* 品牌色：深青（浅底上加深，保证对比度 4.5:1 以上） */
  --brand: #0e7490;
  --brand-600: #0891b2;
  --brand-400: #0e7490;
  --brand-050: rgba(14, 116, 144, 0.1);
  --accent: #6d28d9;
  --accent-050: rgba(109, 40, 217, 0.1);
  --accent-ink: #5b21b6;

  /* 边框（浅色下用深灰半透明） */
  --line: rgba(13, 21, 38, 0.12);
  --line-soft: rgba(13, 21, 38, 0.07);

  /* 阴影（浅色下更轻、更散） */
  --shadow-sm: 0 1px 2px rgba(13, 21, 38, 0.06);
  --shadow-md: 0 14px 40px rgba(13, 21, 38, 0.1);
  --shadow-lg: 0 30px 80px rgba(13, 21, 38, 0.14);
  --glow: 0 0 0 1px rgba(14, 116, 144, 0.16), 0 0 34px rgba(14, 116, 144, 0.1);

  /* 信号色 */
  --danger: #dc2626;
  --danger-ink: #b91c1c;
  --danger-050: rgba(220, 38, 38, 0.08);
  --danger-035: rgba(220, 38, 38, 0.28);
  --danger-line: rgba(220, 38, 38, 0.55);
  --success: #059669;
  --success-ink: #047857;
  --success-050: rgba(5, 150, 105, 0.1);
  --success-035: rgba(5, 150, 105, 0.28);

  /* 品牌半透明衍生 */
  --brand-line: rgba(14, 116, 144, 0.25);
  --brand-line-strong: rgba(14, 116, 144, 0.3);
  --brand-line-hover: rgba(14, 116, 144, 0.4);
  --brand-line-focus: rgba(14, 116, 144, 0.5);
  --brand-line-focus-2: rgba(14, 116, 144, 0.55);
  --brand-hover-050: rgba(14, 116, 144, 0.08);
  --brand-row-hover: rgba(14, 116, 144, 0.045);
  --brand-shadow-sm: rgba(14, 116, 144, 0.18);
  --brand-shadow-md: rgba(14, 116, 144, 0.24);
  --brand-glow: rgba(14, 116, 144, 0.12);
  --accent-line: rgba(109, 40, 217, 0.28);
  --accent-hover-050: rgba(109, 40, 217, 0.14);

  /* 中性半透明衍生 */
  --neutral-050: rgba(13, 21, 38, 0.06);
  --neutral-035: rgba(13, 21, 38, 0.035);
  --selected-bg: rgba(14, 116, 144, 0.2);
  --selected-ink: #0d1526;
  --selection-ink: #0d1526;
  --grid-line: rgba(13, 21, 38, 0.045);
  --scrollbar-track: #eef2f9;
  --scrollbar-thumb: #c3ccdb;
  --scrollbar-thumb-hover: #a7b3c6;

  /* 表面 / 遮罩 / 控件 */
  --header-bg: rgba(255, 255, 255, 0.82);
  --header-bg-scrolled: rgba(255, 255, 255, 0.95);
  --header-shadow: 0 6px 24px rgba(13, 21, 38, 0.08);
  --nav-sheet-bg: rgba(255, 255, 255, 0.99);
  --panel-bg: linear-gradient(160deg, #ffffff 0%, #f4f7fc 100%);
  --card-bg: linear-gradient(165deg, #ffffff 0%, #f8fafd 100%);
  --modal-bg: linear-gradient(170deg, #ffffff 0%, #f8fafd 100%);
  --input-bg: #ffffff;
  --input-bg-focus: #ffffff;
  --subtle-bg: #f1f4fa;
  --subtle-bg-2: #f1f4fa;
  --overlay: rgba(13, 21, 38, 0.42);
  --cover-bg: linear-gradient(140deg, #dbe7f6 0%, #eef3fb 55%, #e4e6fb 100%);
  --cover-ink: rgba(13, 21, 38, 0.78);
  --tag-bg: rgba(255, 255, 255, 0.9);
  --cta-bg: linear-gradient(120deg, #0b3b52 0%, #0e4f6b 45%, #1e3a8a 100%);
  --cta-ink: #ffffff;
  --cta-lead: rgba(238, 243, 251, 0.82);
  --cta-line: rgba(255, 255, 255, 0.2);
  --footer-ink: rgba(74, 85, 104, 0.9);
  --skeleton-1: #e8edf6;
  --skeleton-2: #f2f5fa;
  --avatar-bg: linear-gradient(140deg, rgba(14, 116, 144, 0.16), rgba(109, 40, 217, 0.14));
  --avatar-bg-lg: linear-gradient(140deg, rgba(14, 116, 144, 0.18), rgba(109, 40, 217, 0.16));
  --avatar-shadow: 0 8px 22px rgba(13, 21, 38, 0.12);
  --mark-ink: #ffffff;
  --mark-shadow: 0 4px 14px rgba(14, 116, 144, 0.24);
  --on-brand: #ffffff;
  --ghost-bg: rgba(13, 21, 38, 0.04);
  --light-btn-bg: #0d1526;
  --light-btn-bg-hover: #1e293b;
  --light-btn-ink: #ffffff;
  --outline-light-bg: rgba(255, 255, 255, 0.08);
  --outline-light-ink: #ffffff;
  --outline-light-line: rgba(255, 255, 255, 0.34);
  --ring: rgba(14, 116, 144, 0.14);

  /* 渐变文字（浅底上加深，否则渐变字会发白发飘） */
  --grad-a: #0e7490;
  --grad-b: #2563eb;
  --grad-c: #6d28d9;
  --grad-hero-a: #0891b2;
  --grad-hero-b: #2563eb;
  --grad-hero-c: #7c3aed;
  --grad-stat-a: #0e7490;
  --grad-stat-b: #2563eb;
  --mark-grad: linear-gradient(140deg, #0891b2 0%, #4f7df3 55%, #7c3aed 100%);
  --btn-primary-grad: linear-gradient(120deg, var(--brand-600) 0%, var(--brand) 60%, #0f766e 100%);
  --timeline-grad: linear-gradient(180deg, rgba(14, 116, 144, 0.45), rgba(109, 40, 217, 0.28), transparent);
  --hairline-grad: linear-gradient(90deg, transparent, rgba(14, 116, 144, 0.42), transparent);
  --card-glow: radial-gradient(circle, rgba(14, 116, 144, 0.14), transparent 68%);
  --halo-a: radial-gradient(1000px 520px at 78% -12%, rgba(34, 211, 238, 0.16), transparent 62%);
  --halo-b: radial-gradient(760px 480px at 6% 4%, rgba(139, 92, 246, 0.1), transparent 64%);
  --hero-halo-a: radial-gradient(900px 420px at 82% -8%, rgba(34, 211, 238, 0.16), transparent 60%);
  --hero-halo-b: radial-gradient(700px 380px at 8% 104%, rgba(139, 92, 246, 0.12), transparent 62%);
  --cover-halo: radial-gradient(400px 200px at 78% -20%, rgba(255, 255, 255, 0.75), transparent 62%);
  --cta-halo: radial-gradient(600px 320px at 88% -30%, rgba(34, 211, 238, 0.3), transparent 62%);

  --icon-sun: #d97706;
  --icon-moon: #4338ca;

  /* 云端降级提示（浅色主题） */
  --degrade-bg: linear-gradient(160deg, #ffffff 0%, #f2f7fc 100%);
  --degrade-line: rgba(14, 116, 144, 0.2);
  --degrade-icon-bg: rgba(14, 116, 144, 0.1);
  --degrade-icon-ink: #0e7490;
  --degrade-title-ink: #0d1526;
  --degrade-text-ink: #4a5568;
  --degrade-notice-bg: rgba(14, 116, 144, 0.07);
  --degrade-notice-line: rgba(14, 116, 144, 0.2);
  --degrade-notice-ink: #0e7490;
  --degrade-notice-text: #3d4a5c;
  --degrade-dot: #0e7490;

  /* ---------- 课程中心（列表 / 详情）----------
     浅色底上分类色需要压深，否则浅底 + 亮青完全不可读 */
  --cat1: #0e7490;
  --cat1-050: rgba(14, 116, 144, 0.1);
  --cat2: #6d28d9;
  --cat2-050: rgba(109, 40, 217, 0.1);
  --cat3: #047857;
  --cat3-050: rgba(4, 120, 87, 0.1);
  --cat4: #b45309;
  --cat4-050: rgba(180, 83, 9, 0.11);
  --cat5: #be185d;
  --cat5-050: rgba(190, 24, 93, 0.1);

  --cat-ink: #16233a;
  --cat-band-line: rgba(30, 58, 95, 0.16);
  --ccard-bg: var(--surface);
  --ccard-hover-line: var(--brand-line-hover);
  --chip-bg: var(--surface-2);
  --chip-ink: var(--ink-2);
  --chip-line: var(--line);
  --outline-num-bg: var(--surface-2);
  --outline-num-ink: var(--brand);
  --outline-num-line: var(--line);
  --crumb-ink: var(--ink-3);
  --crumb-cur-ink: var(--ink);
  --badge-bg: var(--surface-2);
  --badge-ink: var(--ink-2);
  --badge-line: var(--line);

  color-scheme: light;
}

:root, [data-theme="dark"] { color-scheme: dark; }

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  letter-spacing: 0.01em;
}

/* 全站科技感底纹：细网格 + 顶部光晕 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    var(--halo-a),
    var(--halo-b),
    linear-gradient(var(--grid-line) 1px, transparent 1px) 0 0 / 100% 56px,
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px) 0 0 / 56px 100%;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; }

h1, h2, h3, h4 {
  margin: 0;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.25;
  color: var(--ink);
}

p { margin: 0; }

::selection { background: var(--selected-bg); color: var(--selection-ink); }

/* 滚动条（跟随主题） */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--scrollbar-track); }
::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb);
  border-radius: 999px;
  border: 2px solid var(--scrollbar-track);
}
::-webkit-scrollbar-thumb:hover { background: var(--scrollbar-thumb-hover); }

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- 通用排版 ---------- */

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--brand);
}

.eyebrow::before {
  content: "";
  width: 24px;
  height: 1px;
  background: var(--brand);
  box-shadow: 0 0 8px var(--brand-shadow-md);
}

.section { padding: 104px 0; }
.section--soft { background: var(--bg-soft); }

.section-head { max-width: 720px; margin-bottom: 56px; }
.section-head h2 {
  font-size: clamp(1.75rem, 3.2vw, 2.5rem);
  margin: 18px 0 16px;
}
.section-head p { color: var(--ink-2); font-size: 1.0625rem; }
.section-head--center { margin-left: auto; margin-right: auto; text-align: center; }
.section-head--center .eyebrow { justify-content: center; }

.muted { color: var(--ink-3); }

/* 渐变标题字（用于强调短语） */
.grad {
  background: linear-gradient(100deg, var(--grad-a) 0%, var(--grad-b) 55%, var(--grad-c) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--brand);
}

/* ---------- 按钮 ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 46px;
  padding: 0 24px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease,
    border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
}

.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.btn--primary {
  background: var(--btn-primary-grad);
  color: var(--on-brand);
  box-shadow: 0 6px 22px var(--brand-shadow-sm);
}
.btn--primary:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 10px 30px var(--brand-shadow-md);
}

.btn--ghost { background: var(--ghost-bg); color: var(--brand-400); border-color: var(--line); }
.btn--ghost:hover:not(:disabled) { border-color: var(--brand-line-focus-2); background: var(--brand-050); color: var(--brand); }

.btn--light { background: var(--light-btn-bg); color: var(--light-btn-ink); }
.btn--light:hover:not(:disabled) { background: var(--light-btn-bg-hover); transform: translateY(-1px); }

.btn--outline-light { background: var(--outline-light-bg); color: var(--outline-light-ink); border-color: var(--outline-light-line); }
.btn--outline-light:hover:not(:disabled) { border-color: var(--brand); color: var(--brand-400); background: var(--brand-hover-050); }

.btn--sm { height: 38px; padding: 0 18px; font-size: 14px; }
.btn--block { width: 100%; }

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
  font-size: 15px;
  color: var(--brand);
}
.link-arrow span { transition: transform 0.2s ease; }
.link-arrow:hover span { transform: translateX(4px); }

/* ---------- 顶部导航 ---------- */

.header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: var(--header-bg);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.25s ease, box-shadow 0.25s ease, background-color 0.25s ease;
}

.header.is-scrolled {
  background: var(--header-bg-scrolled);
  border-bottom-color: var(--line);
  box-shadow: var(--header-shadow);
}

.header__inner {
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand { display: flex; align-items: center; gap: 12px; flex: 0 0 auto; }
.brand__mark {
  width: 38px;
  height: 38px;
  border-radius: 11px;
  background: var(--mark-grad);
  color: var(--mark-ink);
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 15px;
  letter-spacing: -0.02em;
  box-shadow: var(--mark-shadow);
}
.brand__text strong { display: block; font-size: 16px; letter-spacing: 0.02em; color: var(--ink); }
.brand__text span {
  display: block;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--ink-4);
  text-transform: uppercase;
}

.nav { display: flex; align-items: center; gap: 26px; }
.nav__link {
  position: relative;
  font-size: 15px;
  color: var(--ink-2);
  font-weight: 500;
  padding: 6px 0;
  white-space: nowrap;
  transition: color 0.2s ease;
}
.nav__link:hover { color: var(--brand); }
.nav__link.is-active { color: var(--brand); font-weight: 600; }
.nav__link.is-active::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 2px;
  border-radius: 2px;
  background: var(--brand);
  box-shadow: 0 0 10px var(--brand-shadow-md);
}

.header__actions { display: flex; align-items: center; gap: 12px; flex: 0 0 auto; }
#nav-auth { display: flex; align-items: center; gap: 10px; }

/* ---------- 明暗主题切换按钮 ---------- */

.theme-toggle {
  width: 40px; height: 40px;
  flex: 0 0 40px;
  display: inline-grid;
  place-items: center;
  padding: 0;
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 10px;
  color: var(--ink-2);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: border-color 0.2s ease, color 0.2s ease, background-color 0.2s ease, transform 0.2s ease;
}
.theme-toggle:hover {
  border-color: var(--brand-line-focus-2);
  color: var(--brand);
  background: var(--brand-050);
  transform: translateY(-1px);
}
.theme-toggle:focus-visible { outline: 2px solid var(--brand); outline-offset: 2px; }
.theme-toggle:active { transform: scale(0.94); }

/* 两枚图标叠放，靠 data-theme 切换旋转与透明度，避免重排 */
.theme-toggle__icon {
  grid-area: 1 / 1;
  display: grid;
  place-items: center;
  transition: opacity 0.28s ease, transform 0.4s cubic-bezier(0.22, 0.61, 0.36, 1);
}
.theme-toggle__icon svg { width: 19px; height: 19px; display: block; }
.theme-toggle__icon--sun { color: var(--icon-sun); opacity: 0; transform: rotate(-70deg) scale(0.6); }
.theme-toggle__icon--moon { color: var(--icon-moon); opacity: 1; transform: none; }

/* 浅色下显示太阳（即"当前是浅色，点击可切回深色"的语义由 aria-label 承担） */
[data-theme="light"] .theme-toggle__icon--sun { opacity: 1; transform: none; }
[data-theme="light"] .theme-toggle__icon--moon { opacity: 0; transform: rotate(70deg) scale(0.6); }

@media (max-width: 900px) {
  .theme-toggle { width: 38px; height: 38px; flex-basis: 38px; }
}
@media (max-width: 420px) {
  .header__actions { gap: 8px; }
  .theme-toggle { order: 2; }
  #nav-auth { order: 1; }
  .nav-toggle { order: 3; }
}

.nav-toggle {
  display: none;
  width: 40px; height: 40px;
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 10px;
  cursor: pointer;
  padding: 0;
}
.nav-toggle span {
  display: block;
  width: 18px; height: 1.5px;
  margin: 3.5px auto;
  background: var(--ink);
  transition: transform 0.25s ease, opacity 0.2s ease;
}
.nav-toggle.is-open span:nth-child(1) { transform: translateY(5px) rotate(45deg); }
.nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open span:nth-child(3) { transform: translateY(-5px) rotate(-45deg); }

/* 用户区 */
.user-chip {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 4px 14px 4px 4px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
  position: relative;
  transition: border-color 0.2s ease;
}
.user-chip:hover { border-color: var(--brand-line-focus-2); }
.user-chip__avatar {
  width: 32px; height: 32px;
  border-radius: 50%;
  background: var(--brand-050);
  color: var(--brand);
  display: grid;
  place-items: center;
  font-size: 13px;
  font-weight: 700;
  overflow: hidden;
}
.user-chip__avatar img { width: 100%; height: 100%; object-fit: cover; }

.user-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  min-width: 208px;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  padding: 8px;
  display: none;
  text-align: left;
  z-index: 20;
}
.user-menu.is-open { display: block; }
.user-menu__head { padding: 10px 12px 12px; border-bottom: 1px solid var(--line-soft); margin-bottom: 6px; }
.user-menu__head strong { display: block; font-size: 14px; color: var(--ink); }
.user-menu__head span { font-size: 12px; color: var(--ink-3); word-break: break-all; }
.user-menu button {
  display: block;
  width: 100%;
  text-align: left;
  padding: 9px 12px;
  border: 0;
  background: transparent;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--ink-2);
  cursor: pointer;
}
.user-menu button:hover { background: var(--brand-050); color: var(--brand); }

/* ---------- 首屏 ---------- */

.hero {
  position: relative;
  padding: 120px 0 96px;
  overflow: hidden;
  background:
    var(--hero-halo-a),
    var(--hero-halo-b);
}

.hero__grid {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 64px;
  align-items: center;
}

.hero h1 {
  font-size: clamp(2.25rem, 4.6vw, 3.75rem);
  line-height: 1.16;
  margin: 22px 0 22px;
  letter-spacing: -0.02em;
}
.hero h1 em {
  font-style: normal;
  background: linear-gradient(100deg, var(--grad-hero-a) 0%, var(--grad-hero-b) 60%, var(--grad-hero-c) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--brand);
  position: relative;
}
.hero__lead {
  font-size: 1.125rem;
  color: var(--ink-2);
  max-width: 560px;
}
.hero__cta { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 36px; }

.hero__panel {
  position: relative;
  border-radius: var(--radius-lg);
  background: var(--panel-bg);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-lg), var(--glow);
  padding: 28px;
}
.hero__panel-head {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding-bottom: 18px; border-bottom: 1px solid var(--line-soft); margin-bottom: 8px;
}
.hero__panel-head strong { font-size: 15px; }
.hero__panel-head span {
  font-size: 12px;
  color: var(--brand);
  border: 1px solid var(--brand-line-strong);
  background: var(--brand-050);
  padding: 2px 10px;
  border-radius: 999px;
}

.hero__stat-row {
  display: flex; align-items: baseline; justify-content: space-between; gap: 12px;
  padding: 16px 0; border-bottom: 1px dashed var(--line-soft);
}
.hero__stat-row:last-child { border-bottom: 0; }
.hero__stat-row span { font-size: 14px; color: var(--ink-2); }
.hero__stat-row i { font-style: normal; font-size: 12px; color: var(--accent); font-weight: 600; white-space: nowrap; }

.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-top: 72px;
  padding-top: 40px;
  border-top: 1px solid var(--line);
}
.stats__item b {
  display: block;
  font-size: clamp(1.6rem, 2.6vw, 2.25rem);
  background: linear-gradient(120deg, var(--grad-stat-a) 0%, var(--grad-stat-b) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--brand);
  letter-spacing: -0.02em;
}
.stats__item span { font-size: 14px; color: var(--ink-3); }

/* ---------- 卡片 ---------- */

.grid { display: grid; gap: 24px; }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }
.grid--2 { grid-template-columns: repeat(2, 1fr); }

.card {
  background: var(--card-bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 32px;
  position: relative;
  overflow: hidden;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 1px;
  background: var(--hairline-grad);
  opacity: 0;
  transition: opacity 0.25s ease;
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--brand-line-strong);
}
.card:hover::before { opacity: 1; }

.card__icon {
  width: 44px; height: 44px;
  border-radius: 12px;
  background: var(--brand-050);
  border: 1px solid var(--brand-line);
  color: var(--brand);
  display: grid; place-items: center;
  margin-bottom: 20px;
  font-size: 18px;
  font-weight: 700;
}
.card h3 { font-size: 1.125rem; margin-bottom: 10px; }
.card p { color: var(--ink-2); font-size: 15px; }

/* 课程卡 */
.course-card {
  display: flex;
  flex-direction: column;
  background: var(--card-bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.course-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--brand-line-hover); }

.course-card__cover {
  aspect-ratio: 16 / 9;
  background:
    var(--cover-halo),
    var(--cover-bg);
  position: relative;
  display: grid;
  place-items: center;
  color: var(--cover-ink);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.04em;
  border-bottom: 1px solid var(--line-soft);
}
.course-card__cover img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.course-card__tag {
  position: absolute;
  top: 14px; left: 14px;
  background: var(--tag-bg);
  border: 1px solid var(--brand-line-focus);
  color: var(--brand);
  font-size: 12px;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 999px;
  z-index: 2;
  backdrop-filter: blur(6px);
}
.course-card__body { padding: 24px; display: flex; flex-direction: column; gap: 12px; flex: 1; }
.course-card__body h3 { font-size: 1.0625rem; line-height: 1.45; }
.course-card__meta { display: flex; flex-wrap: wrap; gap: 8px 16px; font-size: 13px; color: var(--ink-3); }
.course-card__summary { color: var(--ink-2); font-size: 14.5px; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.course-card__foot {
  margin-top: auto;
  padding-top: 16px;
  border-top: 1px solid var(--line-soft);
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
}
.course-card__price { font-size: 1.125rem; font-weight: 700; color: var(--brand); }
.course-card__price small { font-size: 12px; font-weight: 500; color: var(--ink-4); }

/* ---------- 时间线 ---------- */

.timeline { position: relative; padding-left: 28px; }
.timeline::before {
  content: "";
  position: absolute;
  left: 5px; top: 6px; bottom: 6px;
  width: 1px;
  background: var(--timeline-grad);
}
.timeline__item { position: relative; padding-bottom: 36px; }
.timeline__item:last-child { padding-bottom: 0; }
.timeline__item::before {
  content: "";
  position: absolute;
  left: -28px; top: 8px;
  width: 11px; height: 11px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--brand);
  box-shadow: 0 0 10px var(--brand-shadow-md);
}
.timeline__item.is-key::before { background: var(--accent); border-color: var(--accent); box-shadow: 0 0 12px var(--accent-line); }
.timeline__item b { display: block; font-size: 1rem; color: var(--brand); }
.timeline__item strong { display: block; font-size: 1.0625rem; margin: 4px 0 6px; }
.timeline__item p { color: var(--ink-2); font-size: 15px; }

/* ---------- 讲师 / 师资 ---------- */

.teacher {
  display: flex;
  gap: 18px;
  padding: 24px;
  background: var(--card-bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.teacher:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); border-color: var(--brand-line-hover); }
.teacher__avatar {
  width: 62px; height: 62px; flex: 0 0 62px;
  border-radius: 16px;
  background: var(--avatar-bg);
  border: 1px solid var(--brand-line);
  color: var(--brand);
  display: grid; place-items: center;
  font-weight: 700; font-size: 20px;
  overflow: hidden;
}
.teacher__avatar img { width: 100%; height: 100%; object-fit: cover; }
.teacher strong { display: block; font-size: 1.0625rem; }
.teacher em { display: block; font-style: normal; font-size: 13px; color: var(--brand); margin-bottom: 8px; }
.teacher p { font-size: 14px; color: var(--ink-2); }

/* 师资大卡（学院师资页专用） */
.teacher-card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 30px;
  border-radius: var(--radius-lg);
  background: var(--card-bg);
  border: 1px solid var(--line);
  overflow: hidden;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.teacher-card::after {
  content: "";
  position: absolute;
  width: 220px; height: 220px;
  right: -90px; top: -90px;
  border-radius: 50%;
  background: var(--card-glow);
  pointer-events: none;
}
.teacher-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--brand-line-hover); }
.teacher-card__top { display: flex; align-items: center; gap: 16px; position: relative; z-index: 1; }
.teacher-card__avatar {
  width: 72px; height: 72px; flex: 0 0 72px;
  border-radius: 20px;
  background: var(--avatar-bg-lg);
  border: 1px solid var(--brand-line-strong);
  color: var(--brand);
  display: grid; place-items: center;
  font-size: 26px; font-weight: 700;
  overflow: hidden;
  box-shadow: var(--avatar-shadow);
}
.teacher-card__avatar img { width: 100%; height: 100%; object-fit: cover; }
.teacher-card__name { font-size: 1.25rem; }
.teacher-card__role { font-size: 13.5px; color: var(--brand); margin-top: 4px; }
.teacher-card__tags { display: flex; flex-wrap: wrap; gap: 8px; position: relative; z-index: 1; }
.teacher-card p { color: var(--ink-2); font-size: 14.5px; position: relative; z-index: 1; }
.teacher-card__line {
  display: flex; gap: 10px; align-items: baseline;
  font-size: 14px; color: var(--ink-2);
  position: relative; z-index: 1;
  padding-top: 14px; border-top: 1px solid var(--line-soft);
}
.teacher-card__line b { color: var(--ink-3); font-weight: 600; font-size: 12.5px; letter-spacing: 0.06em; white-space: nowrap; }

/* ---------- 数据条 ---------- */

.cta-banner {
  position: relative;
  background:
    var(--cta-halo),
    var(--cta-bg);
  color: var(--cta-ink);
  border: 1px solid var(--cta-line);
  border-radius: var(--radius-lg);
  padding: 64px 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
  flex-wrap: wrap;
  overflow: hidden;
}
.cta-banner h2 { font-size: clamp(1.5rem, 2.6vw, 2.125rem); color: var(--cta-ink); }
.cta-banner p { color: var(--cta-lead); margin-top: 12px; }
.cta-banner .eyebrow { color: var(--brand-400); }
.cta-banner .eyebrow::before { background: var(--brand); }

/* ---------- 表单 ---------- */

.form-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.field { display: flex; flex-direction: column; gap: 8px; }
.field--full { grid-column: 1 / -1; }
.field label { font-size: 14px; font-weight: 600; color: var(--ink-2); }
.field label .req { color: var(--danger); margin-left: 2px; }

.input, .select, .textarea {
  width: 100%;
  border: 1px solid var(--line);
  background: var(--input-bg);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  font-size: 15px;
  font-family: inherit;
  color: var(--ink);
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background-color 0.2s ease;
}
.input::placeholder, .textarea::placeholder { color: var(--ink-4); }
.textarea { min-height: 128px; resize: vertical; line-height: 1.7; }
.select { appearance: none; -webkit-appearance: none; cursor: pointer; padding-right: 38px;
  background-image: linear-gradient(45deg, transparent 50%, var(--ink-3) 50%), linear-gradient(135deg, var(--ink-3) 50%, transparent 50%);
  background-position: calc(100% - 18px) 50%, calc(100% - 13px) 50%;
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
}
.select option { background: var(--surface-2); color: var(--ink); }
.input:focus, .select:focus, .textarea:focus {
  outline: none;
  background: var(--input-bg-focus);
  border-color: var(--brand-line-focus-2);
  box-shadow: 0 0 0 3px var(--ring);
}
.input.is-error, .textarea.is-error { border-color: var(--danger-line); }
.field__error { font-size: 13px; color: var(--danger); min-height: 0; }
.field__hint { font-size: 12.5px; color: var(--ink-4); }

.input-group { display: flex; gap: 10px; }
.input-group .input { flex: 1; min-width: 0; }
.input-group .btn { flex: 0 0 auto; }

.form-note { font-size: 13px; color: var(--ink-3); margin-top: 4px; }

/* 原生文件选择控件在深色下的可读性 */
input[type="file"].input { padding: 9px 12px; font-size: 13.5px; color: var(--ink-2); }
input[type="file"].input::file-selector-button {
  margin-right: 12px;
  border: 1px solid var(--line);
  background: var(--surface-3);
  color: var(--brand-400);
  padding: 6px 14px;
  border-radius: 999px;
  font-family: inherit;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
}
input[type="file"].input::file-selector-button:hover { border-color: var(--brand-line-focus); color: var(--brand); }

.alert {
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  font-size: 14px;
  border: 1px solid transparent;
}
.alert--error { background: var(--danger-050); border-color: var(--danger-035); color: var(--danger-ink); }
.alert--success { background: var(--success-050); border-color: var(--success-035); color: var(--success-ink); }
.alert--info { background: var(--brand-050); border-color: var(--brand-line-strong); color: var(--brand-400); }

/* ---------- 联系信息卡 ---------- */

.contact-card {
  display: flex; gap: 18px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card-bg);
  transition: transform 0.25s ease, border-color 0.25s ease;
}
.contact-card:hover { transform: translateY(-3px); border-color: var(--brand-line-strong); }
.contact-card__icon {
  width: 42px; height: 42px; flex: 0 0 42px;
  border-radius: 12px;
  background: var(--brand-050);
  border: 1px solid var(--brand-line);
  color: var(--brand);
  display: grid; place-items: center;
  font-size: 17px;
}
.contact-card strong { display: block; font-size: 15px; }
.contact-card span { display: block; font-size: 14.5px; color: var(--ink-2); margin-top: 4px; }
.contact-card small { display: block; font-size: 12.5px; color: var(--ink-4); margin-top: 6px; }

/* ---------- 弹窗 ---------- */

.modal {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: var(--overlay);
  backdrop-filter: blur(6px);
}
.modal.is-open { display: flex; animation: fade 0.2s ease; }

.modal__dialog {
  width: 100%;
  max-width: 460px;
  max-height: calc(100vh - 48px);
  overflow-y: auto;
  background: var(--modal-bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 32px;
  animation: rise 0.24s ease;
}
.modal__dialog--wide { max-width: 620px; }

.modal__head { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; margin-bottom: 22px; }
.modal__head h3 { font-size: 1.375rem; }
.modal__head p { font-size: 14px; color: var(--ink-3); margin-top: 6px; }
.modal__close {
  border: 0; background: transparent; cursor: pointer;
  font-size: 22px; line-height: 1; color: var(--ink-4); padding: 2px 6px; border-radius: 6px;
}
.modal__close:hover { background: var(--surface-3); color: var(--ink); }

.tabs { display: flex; gap: 4px; background: var(--subtle-bg); border: 1px solid var(--line-soft); padding: 4px; border-radius: 999px; margin-bottom: 24px; }
.tabs button {
  flex: 1;
  border: 0; background: transparent;
  padding: 9px 12px;
  border-radius: 999px;
  font-size: 14px; font-weight: 600; color: var(--ink-3);
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease;
}
.tabs button.is-active { background: var(--brand-050); color: var(--brand); box-shadow: inset 0 0 0 1px var(--brand-line-strong); }

.modal__foot { margin-top: 20px; font-size: 13.5px; color: var(--ink-3); text-align: center; }
.modal__foot a { color: var(--brand); font-weight: 600; cursor: pointer; }

.divider {
  display: flex; align-items: center; gap: 12px;
  margin: 22px 0;
  font-size: 12px; color: var(--ink-4);
}
.divider::before, .divider::after { content: ""; flex: 1; height: 1px; background: var(--line); }

/* ---------- 页脚 ---------- */

.footer { background: var(--bg-deep); color: var(--footer-ink); padding: 72px 0 32px; border-top: 1px solid var(--line); }
.footer__grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 40px; }
.footer h4 { color: var(--ink); font-size: 15px; margin-bottom: 18px; }
.footer ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; font-size: 14.5px; }
.footer a:hover { color: var(--brand); }
.footer__brand .brand__mark { background: var(--mark-grad); }
.footer__brand p { font-size: 14.5px; margin-top: 18px; max-width: 320px; }
.footer__bottom {
  margin-top: 56px; padding-top: 24px;
  border-top: 1px solid var(--line);
  display: flex; justify-content: space-between; gap: 16px;
  font-size: 13px; color: var(--ink-4);
  flex-wrap: wrap;
}

/* ICP 备案号：工信部要求首页底部展示并链接到 beian.miit.gov.cn
   用 --ink-3 而非 --ink-4：后者在深空底上对比度约 3:1，低于 WCAG AA 的 4.5:1，
   备案号属于合规信息，必须清晰可读。 */
.footer__icp {
  color: var(--ink-3);
  text-decoration: none;
  transition: color 0.2s ease;
}
.footer__icp:hover { color: var(--brand); text-decoration: underline; }

@media (max-width: 640px) {
  .footer__bottom { flex-direction: column; gap: 10px; }
}

/* ---------- 后台管理 ---------- */

.admin-tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 28px; }
.admin-tabs button {
  border: 1px solid var(--line);
  background: var(--surface);
  padding: 9px 18px;
  border-radius: 999px;
  font-size: 14px; font-weight: 600; color: var(--ink-2);
  cursor: pointer;
  transition: all 0.2s ease;
}
.admin-tabs button:hover { border-color: var(--brand-line-hover); color: var(--brand-400); }
.admin-tabs button.is-active {
  background: var(--brand-050);
  border-color: var(--brand-line-focus-2);
  color: var(--brand);
  box-shadow: 0 0 18px var(--brand-glow);
}

.table-wrap { border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; background: var(--surface); }
.table { width: 100%; border-collapse: collapse; font-size: 14.5px; }
.table th {
  text-align: left;
  padding: 14px 18px;
  background: var(--subtle-bg-2);
  font-size: 13px;
  color: var(--ink-3);
  font-weight: 600;
  white-space: nowrap;
}
.table td { padding: 14px 18px; border-top: 1px solid var(--line-soft); vertical-align: top; color: var(--ink-2); }
.table tr:hover td { background: var(--brand-row-hover); }

.tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  background: var(--brand-050);
  border: 1px solid var(--brand-line);
  color: var(--brand);
}
.tag--gold { background: var(--accent-050); border-color: var(--accent-line); color: var(--accent-ink); }
.tag--gray { background: var(--neutral-050); border-color: var(--line); color: var(--ink-3); }
.tag--green { background: var(--success-050); border-color: var(--success-035); color: var(--success-ink); }

.empty {
  padding: 56px 24px;
  text-align: center;
  color: var(--ink-3);
  font-size: 15px;
}
.empty strong { display: block; color: var(--ink); margin-bottom: 6px; font-size: 16px; }

.skeleton {
  background: linear-gradient(90deg, var(--skeleton-1) 25%, var(--skeleton-2) 37%, var(--skeleton-1) 63%);
  background-size: 400% 100%;
  animation: shimmer 1.3s ease infinite;
  border-radius: var(--radius-sm);
}
@keyframes shimmer { 0% { background-position: 100% 50%; } 100% { background-position: 0 50%; } }

/* ---------- 动效 ---------- */

.reveal { opacity: 0; transform: translateY(16px); }
.reveal.is-in {
  opacity: 1;
  transform: none;
  transition: opacity 0.6s cubic-bezier(0.22, 0.61, 0.36, 1),
    transform 0.6s cubic-bezier(0.22, 0.61, 0.36, 1);
}

@keyframes fade { from { opacity: 0; } to { opacity: 1; } }
@keyframes rise { from { opacity: 0; transform: translateY(12px); } to { opacity: 1; transform: none; } }

/* ---------- 主题切换过渡 ----------
   只在用户点击切换的那一瞬间挂上 .is-theming，避免首屏加载时
   整页颜色渐变造成视觉拖沓。 */

html.is-theming,
html.is-theming *,
html.is-theming *::before,
html.is-theming *::after {
  transition: background-color 0.32s ease, background-image 0.32s ease,
    border-color 0.32s ease, color 0.32s ease, box-shadow 0.32s ease !important;
  transition-delay: 0s !important;
}

/* ---------- 响应式 ---------- */

@media (max-width: 1100px) {
  .nav { gap: 20px; }
  .nav__link { font-size: 14.5px; }
}

@media (max-width: 1024px) {
  .hero__grid { grid-template-columns: 1fr; gap: 48px; }
  .hero { padding: 88px 0 72px; }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
  .grid--3 { grid-template-columns: repeat(2, 1fr); }
  .footer__grid { grid-template-columns: 1fr 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); gap: 28px; }
}

@media (max-width: 900px) {
  .nav {
    position: fixed;
    top: var(--header-h);
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--nav-sheet-bg);
    backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--line);
    padding: 8px 24px 20px;
    box-shadow: var(--shadow-md);
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.22s ease, transform 0.22s ease;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
  }
  .nav.is-open { opacity: 1; transform: none; pointer-events: auto; }
  .nav__link { padding: 14px 0; border-bottom: 1px solid var(--line-soft); font-size: 16px; }
  .nav-toggle { display: block; }
  .section { padding: 72px 0; }
  .cta-banner { padding: 40px 28px; }
  .form-grid { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .grid--2, .grid--3, .grid--4 { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr; }
  .container { padding: 0 20px; }
  .card, .course-card__body, .teacher, .teacher-card { padding: 22px; }
  .header__actions .btn--sm { padding: 0 14px; }
  .modal__dialog { padding: 24px; }
  .table-wrap { overflow-x: auto; }
  .table { min-width: 560px; }
  .brand__text span { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  .reveal { opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}

/* ==========================================================================
   云端降级提示：静态展示地址下，把 CORS 报错换成友好引导
   —— 颜色一律走变量，深色 / 浅色两套均在主题块内定义
   ========================================================================== */

.cloud-degrade {
  max-width: 560px;
  margin: 8px auto;
  padding: 30px 28px;
  text-align: center;
  border: 1px solid var(--degrade-line);
  border-radius: var(--radius);
  background: var(--degrade-bg);
  box-shadow: 0 12px 34px -18px var(--brand-shadow);
}

.cloud-degrade__icon {
  width: 52px;
  height: 52px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 14px;
  background: var(--degrade-icon-bg);
  color: var(--degrade-icon-ink);
}

.cloud-degrade__title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 650;
  color: var(--degrade-title-ink);
  letter-spacing: 0.01em;
}

.cloud-degrade__text {
  margin: 0 0 22px;
  font-size: 13.5px;
  line-height: 1.75;
  color: var(--degrade-text-ink);
  text-align: left;
}

.cloud-degrade__actions {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 4px;
}

/* 顶部轻提示条 */
.cloud-notice {
  position: relative;
  z-index: 40;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 20px;
  font-size: 12.5px;
  background: var(--degrade-notice-bg);
  border-bottom: 1px solid var(--degrade-notice-line);
  color: var(--degrade-notice-text);
}

.cloud-notice__dot {
  flex: 0 0 auto;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--degrade-dot);
  box-shadow: 0 0 0 3px var(--degrade-icon-bg);
}

.cloud-notice__text {
  flex: 1 1 auto;
  min-width: 0;
}

.cloud-notice__link {
  flex: 0 0 auto;
  color: var(--degrade-notice-ink);
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}

.cloud-notice__link:hover { text-decoration: underline; }

.cloud-notice__close {
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  padding: 0;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--degrade-notice-text);
  font-size: 17px;
  line-height: 1;
  cursor: pointer;
  opacity: 0.7;
}

.cloud-notice__close:hover { opacity: 1; background: var(--degrade-icon-bg); }

@media (max-width: 640px) {
  .cloud-degrade { padding: 24px 20px; }
  .cloud-degrade__text { font-size: 13px; }
  .cloud-notice { padding: 9px 14px; font-size: 12px; gap: 8px; }
  .cloud-notice__text { display: none; }
}

/* ==========================================================================
   课程中心：列表页 + 详情页
   —— 课程内容已静态化写进 HTML，本区块只负责版式与主题适配。
   —— 硬规则：所有颜色一律走上方主题块内的变量，深色 / 浅色两套均已定义。
   ========================================================================== */

/* ---------- 分类筛选栏 ---------- */

.cfilter {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 6px 0 2px;
}
.cfilter__btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 40px;
  padding: 0 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  color: var(--ink-2);
  font: inherit;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: color 0.2s ease, background 0.2s ease, border-color 0.2s ease;
}
.cfilter__btn:hover {
  color: var(--ink);
  border-color: var(--brand-line-hover);
  background: var(--surface-2);
}
.cfilter__btn.is-active {
  color: var(--on-brand);
  background: var(--brand);
  border-color: var(--brand);
}
.cfilter__num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 20px;
  height: 20px;
  padding: 0 6px;
  border-radius: 999px;
  background: var(--surface-3);
  color: var(--ink-3);
  font-size: 11.5px;
  font-weight: 700;
}
.cfilter__btn.is-active .cfilter__num {
  background: var(--brand-050);
  color: var(--on-brand);
}

/* ---------- 课程卡片网格 ---------- */

.cgrid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}
.cgrid--mini { grid-template-columns: repeat(3, 1fr); gap: 18px; }

.ccard {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--ccard-bg);
  color: inherit;
  text-decoration: none;
  overflow: hidden;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.ccard:hover {
  transform: translateY(-4px);
  border-color: var(--ccard-hover-line);
  box-shadow: var(--shadow-md);
}
.ccard:focus-visible {
  outline: 2px solid var(--brand-line-focus);
  outline-offset: 3px;
}

/* 顶部色带：按分类换色，颜色取 --catN，深/浅两套均已定义 */
.ccard__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 22px;
  border-bottom: 1px solid var(--cat-band-line);
  background: var(--surface-2);
}
.ccard__top--c1 { background: var(--cat1-050); }
.ccard__top--c2 { background: var(--cat2-050); }
.ccard__top--c3 { background: var(--cat3-050); }
.ccard__top--c4 { background: var(--cat4-050); }
.ccard__top--c5 { background: var(--cat5-050); }
.ccard__top--c1 .ccard__cat { color: var(--cat1); }
.ccard__top--c2 .ccard__cat { color: var(--cat2); }
.ccard__top--c3 .ccard__cat { color: var(--cat3); }
.ccard__top--c4 .ccard__cat { color: var(--cat4); }
.ccard__top--c5 .ccard__cat { color: var(--cat5); }

.ccard__cat { font-size: 13px; font-weight: 700; letter-spacing: 0.02em; }
.ccard__level {
  font-size: 12px;
  font-weight: 600;
  color: var(--ink-3);
  padding: 3px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--ccard-bg);
  white-space: nowrap;
}

.ccard__body {
  display: flex;
  flex-direction: column;
  flex: 1;
  gap: 12px;
  padding: 24px 22px;
}
.ccard__title {
  font-size: 1.0625rem;
  line-height: 1.45;
  color: var(--ink);
  margin: 0;
}
.ccard__summary {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink-2);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.ccard__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  font-size: 12.5px;
  color: var(--ink-3);
}
.ccard__meta span { position: relative; }
.ccard__meta span + span::before {
  content: "";
  position: absolute;
  left: -9px;
  top: 50%;
  width: 3px;
  height: 3px;
  margin-top: -1.5px;
  border-radius: 50%;
  background: var(--ink-4);
}
.ccard__tags { display: flex; flex-wrap: wrap; gap: 7px; }
.ccard__foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-top: auto;
  padding-top: 14px;
  border-top: 1px solid var(--line-soft);
}
.ccard__price { font-size: 1.25rem; font-weight: 700; color: var(--brand); }
.ccard__price small { font-size: 12px; font-weight: 500; color: var(--ink-3); }

/* 迷你卡（详情页「其他课程」）*/
.ccard--mini .ccard__body { padding: 20px; gap: 10px; }
.ccard--mini .ccard__title { font-size: 0.9688rem; }
.ccard__cat--c1 { color: var(--cat1); }
.ccard__cat--c2 { color: var(--cat2); }
.ccard__cat--c3 { color: var(--cat3); }
.ccard__cat--c4 { color: var(--cat4); }
.ccard__cat--c5 { color: var(--cat5); }
.ccard--mini .ccard__cat { font-size: 12px; font-weight: 700; letter-spacing: 0.02em; }

.cempty {
  padding: 72px 24px;
  text-align: center;
  color: var(--ink-3);
  font-size: 15px;
}
.cempty strong { display: block; color: var(--ink); font-size: 17px; margin-bottom: 8px; }

/* ---------- 标签 / 徽章 ---------- */

.chip {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid var(--chip-line);
  background: var(--chip-bg);
  color: var(--chip-ink);
  font-size: 12px;
  font-weight: 600;
  white-space: nowrap;
}

.badge {
  display: inline-flex;
  align-items: center;
  height: 26px;
  padding: 0 12px;
  border-radius: 999px;
  border: 1px solid var(--badge-line);
  background: var(--badge-bg);
  color: var(--badge-ink);
  font-size: 12.5px;
  font-weight: 600;
  white-space: nowrap;
}
.badge--cat { color: var(--cat-ink); border-color: transparent; }
.badge--c1 { background: var(--cat1-050); color: var(--cat1); }
.badge--c2 { background: var(--cat2-050); color: var(--cat2); }
.badge--c3 { background: var(--cat3-050); color: var(--cat3); }
.badge--c4 { background: var(--cat4-050); color: var(--cat4); }
.badge--c5 { background: var(--cat5-050); color: var(--cat5); }

/* ---------- 面包屑 ---------- */

.crumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 13px;
  color: var(--crumb-ink);
}
.crumb a { color: var(--crumb-ink); text-decoration: none; transition: color 0.2s ease; }
.crumb a:hover { color: var(--brand); }
.crumb span { color: var(--ink-4); }
.crumb__cur { color: var(--crumb-cur-ink); font-weight: 600; }

/* ---------- 课程详情头部 ---------- */

.cdetail__head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 340px;
  gap: 48px;
  align-items: start;
}
.cdetail__badges { display: flex; flex-wrap: wrap; gap: 9px; margin-bottom: 4px; }
.cdetail__tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 22px; }

.cdetail__card {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  padding: 28px 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
}
.cdetail__price {
  font-size: 2rem;
  font-weight: 700;
  color: var(--brand);
  line-height: 1.2;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: 20px;
}
.cdetail__price small { font-size: 13px; font-weight: 500; color: var(--ink-3); margin-left: 4px; }

.cdetail__facts {
  display: grid;
  gap: 12px;
  margin: 0 0 24px;
}
.cdetail__facts > div {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
}
.cdetail__facts dt { font-size: 13px; color: var(--ink-3); white-space: nowrap; }
.cdetail__facts dd {
  margin: 0;
  font-size: 13.5px;
  font-weight: 600;
  color: var(--ink);
  text-align: right;
}

/* ---------- 说明面板（适合人群）---------- */

.panel {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  padding: 28px 30px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}
.panel__icon {
  flex: none;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border-radius: 12px;
  background: var(--brand-050);
  color: var(--brand);
}
.panel__title { font-size: 1.0625rem; margin: 0 0 8px; color: var(--ink); }
.panel__text { margin: 0; font-size: 15px; line-height: 1.8; color: var(--ink-2); }

/* ---------- 模块大纲 ---------- */

.outline { display: grid; gap: 18px; }
.outline__item {
  display: flex;
  gap: 22px;
  padding: 26px 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  transition: border-color 0.25s ease, box-shadow 0.25s ease;
}
.outline__item:hover { border-color: var(--ccard-hover-line); box-shadow: var(--shadow-sm); }
.outline__num {
  flex: none;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border-radius: 12px;
  border: 1px solid var(--outline-num-line);
  background: var(--outline-num-bg);
  color: var(--outline-num-ink);
  font-size: 15px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}
.outline__main { flex: 1; min-width: 0; }
.outline__title { font-size: 1.0625rem; margin: 0 0 12px; color: var(--ink); }
.outline__points {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 9px;
}
.outline__points li {
  position: relative;
  padding-left: 20px;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--ink-2);
}
.outline__points li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 10px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--brand);
  box-shadow: 0 0 0 3px var(--brand-050);
}

/* ---------- 报名 CTA ---------- */

.cta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  flex-wrap: wrap;
  padding: 44px 46px;
  border: 1px solid var(--cta-line);
  border-radius: var(--radius-lg);
  background: var(--cta-halo), var(--cta-bg);
}
.cta h2 { font-size: clamp(1.375rem, 2.4vw, 1.875rem); color: var(--cta-ink); margin: 0; }
.cta p { color: var(--cta-lead); margin: 10px 0 0; font-size: 15px; }
.cta__actions { display: flex; gap: 12px; flex-wrap: wrap; }

/* ---------- 响应式 ---------- */

@media (max-width: 1024px) {
  .cdetail__head { grid-template-columns: 1fr; gap: 32px; }
  .cdetail__card { position: static; }
  .cgrid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 760px) {
  .cgrid, .cgrid--mini { grid-template-columns: 1fr; }
  .cfilter { gap: 8px; }
  .cfilter__btn { height: 36px; padding: 0 13px; font-size: 13px; }
  .outline__item { gap: 16px; padding: 22px 20px; }
  .outline__num { width: 40px; height: 40px; font-size: 14px; }
  .panel { flex-direction: column; gap: 14px; padding: 24px 22px; }
  .cta { flex-direction: column; align-items: flex-start; padding: 32px 24px; }
  .cta__actions { width: 100%; }
  .cta__actions .btn { flex: 1; justify-content: center; }
  .cdetail__card { padding: 24px 22px; }
  .cdetail__price { font-size: 1.75rem; }
}