/* ==========================================================================
   ImmTelecom - 官方推广落地页极简原生样式表
   Design Style: Warm Nordic-minimalist human-centric UI
   Palette: Warm oatmeal canvas (#f9f8f6), Matte graphite wool (#22252a),
            Calming denim blue (#2563eb), Soft parchment white (#ffffff)
   Strictly zero robotic AI figures. Pure Vanilla CSS & HTML.
   ========================================================================== */

/* -------------------- 颜色变量与北欧人本主义设计令牌 -------------------- */
:root {
  /* 默认：白天模式 (Warm Nordic Light Mode) */
  --bg-body: #f9f8f6;               /* 温暖燕麦画布 Warm Oatmeal Canvas */
  --bg-surface: #ffffff;            /* 柔和羊皮纸白 Soft Parchment White */
  --bg-surface-elevated: #ffffff;
  --bg-card: #ffffff;
  --bg-subtle: #f2efe9;             /* 燕麦灰微深底色 */
  --bg-glass: rgba(249, 248, 246, 0.88);
  --bg-tag: #eceae3;                /* 质感羊毛浅灰标签底 */

  --text-main: #18191c;             /* 哑光石墨羊毛深色 Matte Graphite Wool */
  --text-secondary: #525866;        /* 沉稳暖炭灰 */
  --text-muted: #798194;            /* 柔和次级说明灰 */
  --text-tag: #18191c;              /* 质感黑灰标签字 */

  --border-color: #eae6df;          /* 温和燕麦米色边框 */
  --border-hover: #d5cfc4;          /* 悬浮温和边框 */
  --border-focus: #18191c;          /* 聚焦黑灰色 */

  --primary: #18191c;               /* 高级质感哑光石墨黑/黑灰 Matte Graphite Black */
  --primary-hover: #2e323b;         /* 悬浮深炭灰 */
  --primary-light: #eceae3;         /* 羊毛微灰轻盈容器底 */
  --primary-glow: rgba(24, 25, 28, 0.14); /* 柔和暗影光晕 */

  --graphite-wool: #18191c;         /* 哑光石墨羊毛 */
  --wool-banner-bg: #18191c;
  --wool-banner-text: #f9f8f6;

  --accent-green: #15803d;          /* 人本温和植物绿 */
  --accent-amber: #b45309;          /* 温润暖琥珀 */
  --accent-purple: #6d28d9;         /* 雅致深紫 */

  /* 阴影系统：柔和环境光与触觉物理投影 */
  --shadow-sm: 0 1px 3px rgba(24, 25, 28, 0.04), 0 1px 2px rgba(24, 25, 28, 0.03);
  --shadow-md: 0 4px 12px rgba(24, 25, 28, 0.06), 0 2px 4px rgba(24, 25, 28, 0.03);
  --shadow-lg: 0 12px 28px -4px rgba(24, 25, 28, 0.08), 0 4px 8px -2px rgba(24, 25, 28, 0.04);
  --shadow-tactile: 0 4px 0 #dcd6cc, 0 8px 16px rgba(24, 25, 28, 0.06);
  --shadow-tactile-active: 0 1px 0 #dcd6cc, 0 3px 6px rgba(24, 25, 28, 0.04);

  /* 柔和倒角系统 (16px softened rounded corner radii) */
  --radius-xs: 6px;
  --radius-sm: 10px;
  --radius-md: 16px;                /* 核心标准倒角 16px */
  --radius-lg: 20px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* 物理过渡与舒缓节奏 */
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.25s cubic-bezier(0.25, 1, 0.5, 1);
  --transition-theme: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

/* 昼夜模式切换：夜间模式 (Nordic Dark Mode) */
[data-theme="dark"] {
  --bg-body: #14171d;               /* 深色石墨冷夜底色 */
  --bg-surface: #1c2028;            /* 柔和石墨卡片底 */
  --bg-surface-elevated: #242a35;
  --bg-card: #1c2028;
  --bg-subtle: #191c23;
  --bg-glass: rgba(20, 23, 29, 0.88);
  --bg-tag: rgba(255, 255, 255, 0.08);

  --text-main: #f5f4f0;             /* 温暖羊皮纸白字 */
  --text-secondary: #c5cbd5;        /* 次级柔和灰字 */
  --text-muted: #8c95a6;
  --text-tag: #f5f4f0;

  --border-color: #2b313e;
  --border-hover: #3d4658;
  --border-focus: #f5f4f0;

  --primary: #f5f4f0;               /* 钛金白灰高反差主色 */
  --primary-hover: #ffffff;
  --primary-light: rgba(255, 255, 255, 0.08);
  --primary-glow: rgba(255, 255, 255, 0.14);

  --graphite-wool: #1c2028;
  --wool-banner-bg: #101318;
  --wool-banner-text: #f5f4f0;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 12px 28px rgba(0, 0, 0, 0.45);
  --shadow-tactile: 0 4px 0 #12151b, 0 8px 16px rgba(0, 0, 0, 0.3);
  --shadow-tactile-active: 0 1px 0 #12151b, 0 3px 6px rgba(0, 0, 0, 0.2);
}

/* -------------------- 全局重置与呼吸排版 -------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  background-color: var(--bg-body);
  color: var(--text-main);
  line-height: 1.75;                /* Breathable line spacing */
  transition: var(--transition-theme);
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

img, svg {
  vertical-align: middle;
  max-width: 100%;
}

button, input {
  font-family: inherit;
  font-size: inherit;
}

ul {
  list-style: none;
}

/* -------------------- 容器与布局 -------------------- */
.container {
  width: 100%;
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.section {
  padding: 96px 0;
}

.section-muted {
  background-color: var(--bg-subtle);
  transition: var(--transition-theme);
}

.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 56px;
}

.section-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background-color: var(--bg-tag);
  color: var(--text-tag);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  border-radius: var(--radius-full);
  margin-bottom: 16px;
  border: 1px solid rgba(37, 99, 235, 0.15);
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.3;
  color: var(--text-main);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.section-desc {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* -------------------- 触觉物理按键与按钮规范 -------------------- */
/* Tactile soft-physics micro-interactions:
   The CTA button features a gentle pillow-soft compression on click */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 26px;
  font-size: 0.975rem;
  font-weight: 600;
  border-radius: var(--radius-md); /* 16px */
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease, background-color 0.2s ease;
  text-align: center;
  white-space: nowrap;
  line-height: 1;
  position: relative;
  user-select: none;
}

/* 枕柔微弹点击感 (pillow-soft compression) */
.btn:active {
  transform: translateY(2px) scale(0.985);
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff !important;
  box-shadow: 0 4px 14px var(--primary-glow);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 18px var(--primary-glow);
}

.btn-primary:active {
  transform: translateY(2px) scale(0.985);
  box-shadow: 0 2px 6px var(--primary-glow);
}

[data-theme="dark"] .btn-primary {
  background-color: var(--primary);
  color: #14171d !important;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
}

[data-theme="dark"] .btn-primary:hover {
  background-color: var(--primary-hover);
  color: #000000 !important;
  box-shadow: 0 6px 20px rgba(255, 255, 255, 0.18);
}

.btn-secondary {
  background-color: var(--bg-surface);
  color: var(--text-main);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  background-color: var(--bg-subtle);
  border-color: var(--border-hover);
  transform: translateY(-1px);
}

.btn-secondary:active {
  transform: translateY(2px) scale(0.985);
}

.btn-lg {
  padding: 16px 34px;
  font-size: 1.075rem;
  border-radius: var(--radius-md); /* 16px */
}

.btn-block {
  width: 100%;
}

/* -------------------- 顶部导航栏 (Site Header) -------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--bg-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition-theme);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  letter-spacing: -0.02em;
}

.brand-img {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  object-fit: cover;
  display: block;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
  transition: transform 0.2s ease;
}

.brand-logo:hover .brand-img {
  transform: scale(1.05);
}

.footer-brand-img {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  object-fit: cover;
  display: block;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.12);
}

.brand-icon {
  width: 36px;
  height: 36px;
  background-color: var(--primary);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  box-shadow: 0 2px 8px var(--primary-glow);
}

[data-theme="dark"] .brand-icon {
  color: #14171d;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding: 8px 0;
  transition: color var(--transition-fast);
}

.nav-link:hover {
  color: var(--primary);
}

.nav-link.active,
.nav-link:focus-visible {
  color: var(--primary);
  font-weight: 600;
}

.nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--primary);
  transition: width var(--transition-fast);
  border-radius: var(--radius-full);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 14px;
}

/* -------------------- 昼夜模式切换按钮 (精致透明质感) -------------------- */
.theme-toggle-btn {
  position: relative;
  width: 42px;
  height: 42px;
  border-radius: var(--radius-md); /* 16px 舒缓方圆 */
  border: 1px solid var(--border-color);
  background: var(--bg-surface);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  transition: all var(--transition-normal);
  padding: 0;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.theme-toggle-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-1px);
}

.theme-toggle-btn:active {
  transform: translateY(2px);
}

.theme-icon-sun,
.theme-icon-moon {
  width: 19px;
  height: 19px;
  position: absolute;
  transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.25s ease;
}

/* 默认白天模式：显示月亮图标 */
.theme-icon-sun {
  opacity: 0;
  transform: translateY(18px) scale(0.6);
}
.theme-icon-moon {
  opacity: 1;
  transform: translateY(0) scale(1);
}

/* 夜间模式：显示太阳图标 */
[data-theme="dark"] .theme-icon-sun {
  opacity: 1;
  transform: translateY(0) scale(1);
}
[data-theme="dark"] .theme-icon-moon {
  opacity: 0;
  transform: translateY(-18px) scale(0.6);
}

.mobile-toggle-btn {
  display: none;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--text-main);
}

/* -------------------- 主视觉区 (Hero Section) -------------------- */
.hero-section {
  padding: 72px 0 56px;
  position: relative;
}

.hero-content {
  text-align: center;
  max-width: 980px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
}

.hero-badge-dot {
  width: 8px;
  height: 8px;
  background-color: var(--accent-green);
  border-radius: 50%;
}

.hero-title {
  font-size: clamp(2.35rem, 3.4vw, 3.1rem);
  font-weight: 800;
  line-height: 1.32;
  letter-spacing: -0.02em;
  margin-bottom: 24px;
  color: var(--text-main);
  text-wrap: balance;
}

.hero-title-sub {
  display: block;
  font-size: 0.92em;
  letter-spacing: 0.01em;
  margin-bottom: 6px;
}

.hero-title-main {
  display: inline-block;
  white-space: nowrap;
}

.hero-title .brand-highlight {
  display: inline-block;
  position: relative;
  font-weight: 900;
  color: var(--primary);
  background: linear-gradient(135deg, #111317 0%, #3e4452 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

[data-theme="dark"] .hero-title .brand-highlight {
  color: var(--primary);
  background: linear-gradient(135deg, #ffffff 0%, #b0b6c4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-intro {
  font-size: 1.2rem;
  color: var(--text-secondary);
  line-height: 1.8;
  max-width: 760px;
  margin: 0 auto 40px;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 56px;
  flex-wrap: wrap;
}

/* -------------------- 触觉物理操作模块 (3 Tactile Action Keys) --------------------
   Requirements:
   The 3 action modules (Purchase, Invoices, Support) behave like weighted physical tactile keys:
   pressing down visibly depresses the module by 2px with smooth ambient shadow contraction.
   Hovering gently lifts the container with a warm, diffuse drop shadow.
--------------------------------------------------------------------------------- */
.hero-tactile-keys {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  max-width: 960px;
  margin: 0 auto 48px;
  text-align: left;
}

.tactile-key-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 24px 22px;
  box-shadow: var(--shadow-tactile);
  cursor: pointer;
  transition: transform 0.15s cubic-bezier(0.2, 0, 0, 1),
              box-shadow 0.15s cubic-bezier(0.2, 0, 0, 1),
              border-color 0.2s ease;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

/* 悬浮微抬升，温暖漫反射投影 */
.tactile-key-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 0 #dcd6cc, var(--shadow-lg);
  border-color: var(--border-hover);
}

[data-theme="dark"] .tactile-key-card:hover {
  box-shadow: 0 6px 0 #12151b, var(--shadow-lg);
}

/* 物理下沉 2px，阴影收缩 (pressing down visibly depresses by 2px with ambient shadow contraction) */
.tactile-key-card:active {
  transform: translateY(2px);
  box-shadow: var(--shadow-tactile-active);
}

.tactile-key-icon {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}

.tactile-key-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 6px;
}

.tactile-key-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.tactile-key-action {
  margin-top: 16px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
}

/* 核心指标仪表栏 */
.hero-stats-banner {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 28px;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  box-shadow: var(--shadow-sm);
}

.stat-item {
  text-align: center;
  padding: 6px 12px;
}

.stat-number {
  font-size: 1.9rem;
  font-weight: 800;
  color: var(--primary);
  line-height: 1.2;
  margin-bottom: 4px;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* -------------------- 核心优势 (3个图文卡片) -------------------- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 36px 30px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--primary);
  box-shadow: var(--shadow-lg);
}

.feature-icon-wrapper {
  width: 54px;
  height: 54px;
  border-radius: 14px;
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
}

.feature-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-main);
}

.feature-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
}

.feature-points {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: auto;
}

.feature-point-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.feature-point-icon {
  width: 16px;
  height: 16px;
  color: var(--accent-green);
  flex-shrink: 0;
}

/* -------------------- 流媒体图卡展示 (Streaming Cards) -------------------- */
.media-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.media-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 28px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.media-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-hover);
}

.media-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.media-logo-badge {
  font-size: 1.15rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 8px;
}

.media-badge-tag {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: var(--bg-subtle);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.media-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text-main);
}

.media-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 18px;
}

.media-specs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding-top: 16px;
  border-top: 1px solid var(--border-color);
}

.spec-pill {
  font-size: 0.775rem;
  font-weight: 600;
  padding: 4px 10px;
  background: var(--bg-subtle);
  color: var(--text-muted);
  border-radius: var(--radius-xs);
}

/* -------------------- AI 支持图卡展示 (AI Support Cards) --------------------
   Strictly zero robotic AI figures. Humanistic, elegant typography & platform badges.
--------------------------------------------------------------------------- */
.ai-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.ai-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 28px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
}

.ai-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.ai-card-top {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.ai-icon-box {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  font-weight: 800;
  color: #fff;
}

.ai-chatgpt { background-color: #10a37f; }
.ai-claude { background-color: #d97706; }
.ai-gemini { background-color: #2563eb; }
.ai-midjourney { background-color: #6366f1; }
.ai-perplexity { background-color: #0284c7; }
.ai-copilot { background-color: #0f172a; }

.ai-name-group h4 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.2;
}

.ai-name-group span {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.ai-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 16px;
}

.ai-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.ai-tag {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 3px 8px;
  background: var(--bg-subtle);
  border-radius: var(--radius-xs);
  color: var(--text-secondary);
}

/* -------------------- 套餐价格对比表 (真实网络加速器真实定价) -------------------- */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 36px 30px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  position: relative;
}

.pricing-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.pricing-featured {
  border-color: var(--primary);
  border-width: 2px;
  box-shadow: 0 8px 24px var(--primary-glow);
}

.popular-badge {
  position: absolute;
  top: -13px;
  left: 50%;
  transform: translateX(-50%);
  background-color: var(--primary);
  color: #ffffff;
  font-size: 0.775rem;
  font-weight: 700;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  letter-spacing: 0.5px;
}

[data-theme="dark"] .popular-badge {
  background-color: var(--primary);
  color: #14171d;
}

.pricing-header {
  margin-bottom: 24px;
  text-align: center;
}

.plan-name {
  font-size: 1.35rem;
  font-weight: 800;
  margin-bottom: 6px;
  color: var(--text-main);
}

.plan-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.price-box {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 4px;
  margin: 20px 0;
}

.currency {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-main);
}

.amount {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1;
  color: var(--text-main);
}

.period {
  font-size: 0.875rem;
  color: var(--text-muted);
  font-weight: 500;
}

.pricing-features {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 32px;
  padding: 20px 0;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.pricing-feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.925rem;
  color: var(--text-secondary);
}

.pricing-check-icon {
  width: 18px;
  height: 18px;
  color: var(--accent-green);
  flex-shrink: 0;
}

/* -------------------- 用户评价 (User Reviews) -------------------- */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.review-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 30px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.review-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-hover);
}

.stars {
  color: var(--accent-amber);
  margin-bottom: 14px;
  font-size: 1rem;
  letter-spacing: 2px;
}

.review-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 22px;
}

.reviewer-profile {
  display: flex;
  align-items: center;
  gap: 12px;
}

.avatar {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
}

.reviewer-info h5 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.2;
}

.reviewer-info span {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* -------------------- 常见问题解答 (FAQ) -------------------- */
.faq-wrapper {
  max-width: 820px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  margin-bottom: 14px;
  overflow: hidden;
  transition: border-color var(--transition-fast);
}

.faq-item:hover {
  border-color: var(--border-hover);
}

.faq-question {
  width: 100%;
  text-align: left;
  padding: 22px 26px;
  background: none;
  border: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  cursor: pointer;
  transition: color var(--transition-fast);
}

.faq-question:hover {
  color: var(--primary);
}

.faq-icon {
  width: 20px;
  height: 20px;
  color: var(--text-muted);
  transition: transform var(--transition-normal);
  flex-shrink: 0;
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
  color: var(--primary);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  padding: 0 26px;
}

.faq-item.active .faq-answer {
  padding: 0 26px 22px;
}

.faq-answer p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

/* -------------------- 哑光石墨羊毛横幅 (Matte Graphite Wool Banner) -------------------- */
.wool-banner-box {
  background-color: var(--wool-banner-bg);
  color: var(--wool-banner-text);
  border-radius: var(--radius-md); /* 16px */
  padding: 56px 40px;
  text-align: center;
  box-shadow: var(--shadow-lg);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.wool-banner-title {
  font-size: 2.25rem;
  font-weight: 800;
  margin-bottom: 14px;
  line-height: 1.25;
}

.wool-banner-desc {
  font-size: 1.1rem;
  color: #c5cbd5;
  max-width: 620px;
  margin: 0 auto 32px;
  line-height: 1.7;
}

.wool-banner-btn {
  background-color: var(--primary) !important;
  color: #ffffff !important;
  font-size: 1.05rem;
  padding: 15px 36px;
}

.wool-banner-btn:hover {
  background-color: var(--primary-hover) !important;
  transform: translateY(-1px);
}

/* -------------------- 页脚 (严格规范：只保留这四个标题) -------------------- */
.site-footer {
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 50px 0 35px;
  transition: var(--transition-theme);
}

.footer-nav-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 24px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
}

.footer-links-list {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 36px;
  flex-wrap: wrap;
}

.footer-link-item a {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
  padding: 4px 0;
}

.footer-link-item a:hover {
  color: var(--primary);
  text-decoration: underline;
}

.footer-divider {
  width: 100%;
  max-width: 600px;
  height: 1px;
  background: var(--border-color);
  margin: 6px 0;
}

.footer-copyright {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.footer-copyright a {
  color: var(--text-secondary);
  text-decoration: underline;
}

/* -------------------- 子页面通用排版样式 -------------------- */
.subpage-hero {
  padding: 64px 0 44px;
  text-align: center;
  background: var(--bg-subtle);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition-theme);
}

.subpage-title {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 12px;
  color: var(--text-main);
}

.subpage-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto;
}

.content-wrapper {
  max-width: 880px;
  margin: 0 auto;
  padding: 64px 24px 88px;
}

.prose {
  font-size: 1.05rem;
  line-height: 1.85;
  color: var(--text-secondary);
}

.prose h2 {
  font-size: 1.7rem;
  font-weight: 800;
  color: var(--text-main);
  margin: 44px 0 18px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-color);
}

.prose h3 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 28px 0 12px;
}

.prose p {
  margin-bottom: 20px;
}

.prose ul, .prose ol {
  margin-bottom: 24px;
  padding-left: 24px;
}

.prose li {
  margin-bottom: 10px;
  list-style: disc;
}

.callout-box {
  background: var(--bg-surface);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 20px 24px;
  margin: 28px 0;
  border-top: 1px solid var(--border-color);
  border-right: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.callout-alert {
  border-left-color: #dc2626;
  background: rgba(220, 38, 38, 0.04);
}

.callout-title {
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-main);
  margin-bottom: 6px;
}

/* 资讯文章卡片样式 (推荐资讯页面专用) */
.articles-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
  margin-top: 24px;
}

.article-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 28px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
  display: block;
}

/* 资讯条目悬浮轻柔抬升，散发温暖漫反射投影 */
.article-card:hover {
  transform: translateY(-3px);
  border-color: var(--border-hover);
  box-shadow: 0 12px 28px -6px rgba(34, 37, 42, 0.08);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.825rem;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.article-category {
  padding: 3px 10px;
  background-color: var(--bg-tag);
  color: var(--primary);
  font-weight: 600;
  border-radius: var(--radius-full);
}

.article-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 10px;
  line-height: 1.4;
}

.article-excerpt {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 16px;
}

.article-link-text {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--primary);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* -------------------- 深度科普 SEO 文章专用排版 -------------------- */
.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.breadcrumb-nav a {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.breadcrumb-nav a:hover {
  color: var(--primary);
}

.breadcrumb-separator {
  color: var(--border-hover);
}

.article-header {
  margin-bottom: 32px;
}

.article-page-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.35;
  color: var(--text-main);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.article-header-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 0.875rem;
  color: var(--text-muted);
  flex-wrap: wrap;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border-color);
}

.toc-box {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 24px 28px;
  margin: 32px 0;
  box-shadow: var(--shadow-sm);
}

.toc-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.toc-list {
  padding-left: 20px;
  margin-bottom: 0;
}

.toc-list li {
  margin-bottom: 8px;
  font-size: 0.95rem;
  list-style: decimal;
}

.toc-list a {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.toc-list a:hover {
  color: var(--primary);
  text-decoration: underline;
}

.article-table-wrapper {
  overflow-x: auto;
  margin: 28px 0;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  background: var(--bg-surface);
}

.article-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.925rem;
}

.article-table th {
  background: var(--bg-subtle);
  color: var(--text-main);
  font-weight: 700;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border-color);
}

.article-table td {
  padding: 14px 18px;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-secondary);
}

.article-table tr:last-child td {
  border-bottom: none;
}

.article-faq-section {
  margin: 48px 0;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
}

.related-posts-section {
  margin: 56px 0 32px;
  padding-top: 32px;
  border-top: 2px dashed var(--border-color);
}

.related-posts-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
  margin-top: 20px;
}

.related-post-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  padding: 20px;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
  display: block;
}

.related-post-card:hover {
  transform: translateY(-2px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.related-post-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 6px;
  line-height: 1.4;
}

.related-post-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* 网站地图卡片 */
.sitemap-group {
  margin-bottom: 40px;
}

.sitemap-links-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-top: 16px;
}

.sitemap-card {
  display: block;
  padding: 22px;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md); /* 16px */
  transition: all var(--transition-normal);
}

.sitemap-card:hover {
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.sitemap-card-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 6px;
}

.sitemap-card-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* -------------------- 响应式适配 (@media 规范) -------------------- */
.mobile-only-btn {
  display: none !important;
}

@media (max-width: 1024px) {
  .hero-title {
    font-size: 2.75rem;
  }
  .features-grid,
  .media-grid,
  .ai-grid,
  .pricing-grid,
  .reviews-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .hero-tactile-keys {
    grid-template-columns: 1fr;
  }
  .hero-stats-banner {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .section {
    padding: 60px 0;
  }

  .nav-menu {
    position: fixed;
    top: 76px;
    left: 0;
    right: 0;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-color);
    flex-direction: column;
    padding: 24px;
    gap: 18px;
    box-shadow: var(--shadow-lg);
    transform: translateY(-150%);
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
  }

  .nav-menu.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .mobile-toggle-btn {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .mobile-only-btn {
    display: flex !important;
    margin-top: 8px;
    width: 100%;
  }

  .hero-title {
    font-size: 2.1rem;
  }

  .hero-title-main {
    white-space: normal;
    word-break: keep-all;
  }

  .hero-intro {
    font-size: 1.05rem;
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
  }

  .hero-actions .btn {
    width: 100%;
    min-height: 48px;
  }

  /* 手机端单栏完美适配 */
  .features-grid,
  .media-grid,
  .ai-grid,
  .pricing-grid,
  .reviews-grid,
  .hero-stats-banner,
  .hero-tactile-keys,
  .sitemap-links-grid {
    grid-template-columns: 1fr;
  }

  .footer-links-list {
    flex-direction: column;
    gap: 16px;
  }

  .wool-banner-box {
    padding: 40px 20px;
  }

  .wool-banner-title {
    font-size: 1.85rem;
  }

  .btn {
    min-height: 46px; /* 便于手指点击体验 */
  }
}

@media (max-width: 480px) {
  .container {
    padding-left: 18px;
    padding-right: 18px;
  }

  .hero-title {
    font-size: 1.85rem;
  }

  .section-title {
    font-size: 1.75rem;
  }

  .pricing-card {
    padding: 28px 20px;
  }

  .amount {
    font-size: 2.3rem;
  }
}