/* ==========================================================================
   良心云 - 黑白极简设计系统 (Black & White Minimalist Design System)
   Pure Native CSS · Zero Heavy Frameworks · High Accessibility & Performance
   ========================================================================== */

:root {
  /* 黑白灰极简调色板 (Monochrome Palette) */
  --color-black: #09090b;
  --color-black-soft: #121215;
  --color-black-elevated: #18181b;
  --color-gray-900: #27272a;
  --color-gray-800: #3f3f46;
  --color-gray-700: #52525b;
  --color-gray-600: #71717a;
  --color-gray-500: #a1a1aa;
  --color-gray-400: #d4d4d8;
  --color-gray-300: #e4e4e7;
  --color-gray-200: #f4f4f5;
  --color-gray-100: #fafafa;
  --color-white: #ffffff;

  /* 语义化映射 */
  --bg-primary: var(--color-white);
  --bg-secondary: var(--color-gray-100);
  --bg-tertiary: var(--color-gray-200);
  --bg-card: var(--color-white);
  --bg-dark: var(--color-black);
  
  --text-primary: var(--color-black);
  --text-secondary: var(--color-gray-700);
  --text-muted: var(--color-gray-600);
  --text-light: var(--color-gray-400);
  --text-inverse: var(--color-white);

  --border-light: var(--color-gray-300);
  --border-subtle: var(--color-gray-200);
  --border-dark: var(--color-gray-900);

  /* 现代粗圆与无衬线系统字体 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-brand: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

  /* 阴影系统 */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.08);
  --shadow-float: 0 20px 40px rgba(0, 0, 0, 0.12);

  /* 圆角 */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* 过渡 */
  --transition-fast: 150ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-base: 240ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-smooth: 350ms cubic-bezier(0.16, 1, 0.3, 1);

  /* 布局容器最大宽度 */
  --container-max: 1200px;
  --container-narrow: 840px;
  --nav-height: 72px;
}

/* 基础重置 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  background-color: var(--bg-primary);
}

/* 尊重 prefers-reduced-motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* 通用链接与焦点反馈 */
a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

a:focus-visible, button:focus-visible, input:focus-visible {
  outline: 2px solid var(--color-black);
  outline-offset: 3px;
}

img, svg {
  display: block;
  max-width: 100%;
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

ul, ol {
  list-style: none;
}

/* 布局容器 */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.container-narrow {
  width: 100%;
  max-width: var(--container-narrow);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* 章节通用样式 */
.section {
  padding: 96px 0;
  position: relative;
}

.section-alt {
  background-color: var(--bg-secondary);
}

.section-header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 64px auto;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 14px;
  border-radius: var(--radius-full);
  background: var(--color-gray-200);
  color: var(--color-black);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 16px;
  border: 1px solid var(--border-light);
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.25;
  color: var(--text-primary);
  letter-spacing: -0.03em;
  margin-bottom: 16px;
}

.section-subtitle {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* 按钮规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 26px;
  border-radius: var(--radius-full);
  font-size: 0.9375rem;
  font-weight: 700;
  line-height: 1.2;
  transition: all var(--transition-base);
  text-align: center;
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--color-black);
  color: var(--color-white);
  border: 1.5px solid var(--color-black);
}

.btn-primary:hover {
  background-color: #27272a;
  border-color: #27272a;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background-color: transparent;
  color: var(--color-black);
  border: 1.5px solid var(--border-light);
}

.btn-secondary:hover {
  background-color: var(--color-gray-200);
  border-color: var(--color-black);
  transform: translateY(-2px);
}

.btn-secondary:active {
  transform: translateY(0);
}

.btn-lg {
  padding: 15px 34px;
  font-size: 1.0625rem;
}

.btn-sm {
  padding: 8px 18px;
  font-size: 0.875rem;
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  z-index: 100;
  transition: background-color var(--transition-fast), border-color var(--transition-fast);
}

.header-container {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-link {
  display: flex;
  align-items: center;
  transition: opacity var(--transition-fast);
}

.logo-link:hover {
  opacity: 0.85;
}

.logo-img {
  height: 38px;
  width: auto;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-link {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
  position: relative;
  padding: 6px 0;
}

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

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

.nav-link.active::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-black);
  border-radius: var(--radius-full);
}

.nav-badge-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  background-color: var(--color-gray-100);
  border: 1px solid var(--border-light);
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--color-black);
  transition: all var(--transition-fast);
}

.nav-badge-link:hover {
  background-color: var(--color-black);
  color: var(--color-white);
  border-color: var(--color-black);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* 移动端菜单按钮 */
.mobile-menu-toggle {
  display: none;
  width: 42px;
  height: 42px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  background-color: var(--bg-primary);
  color: var(--color-black);
}

.hamburger-icon {
  width: 20px;
  height: 14px;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hamburger-line {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-black);
  transition: transform var(--transition-base), opacity var(--transition-base);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero-section {
  padding: 72px 0 96px 0;
  background: radial-gradient(circle at 50% 0%, rgba(244, 244, 245, 0.8) 0%, rgba(255, 255, 255, 1) 75%);
  border-bottom: 1px solid var(--border-subtle);
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 56px;
  align-items: center;
}

.hero-content {
  max-width: 620px;
}

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

.hero-pill-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--color-black);
  box-shadow: 0 0 0 3px var(--color-gray-200);
}

.hero-title {
  font-size: 3.25rem;
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.04em;
  color: var(--color-black);
  margin-bottom: 22px;
}

/* 品牌“良心云”粗圆风格突出 */
.brand-bold-rounded {
  display: inline-block;
  font-family: var(--font-brand);
  font-weight: 800;
  letter-spacing: -0.02em;
  position: relative;
  padding: 0 4px;
}

.hero-desc {
  font-size: 1.1875rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 36px;
}

.hero-guarantee {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 24px;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.guarantee-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.guarantee-icon {
  width: 16px;
  height: 16px;
  stroke: var(--color-black);
}

/* Hero 右侧动态错落图卡 */
.hero-visual {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.dynamic-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  padding: 24px;
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth);
}

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

.dynamic-card-matrix {
  position: relative;
  z-index: 2;
  border-left: 4px solid var(--color-black);
}

.dynamic-card-protocol {
  background: var(--color-black);
  color: var(--color-white);
  border-color: var(--color-gray-900);
  margin-left: 28px;
  position: relative;
  z-index: 1;
}

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

.badge-status {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: var(--color-gray-100);
  border: 1px solid var(--border-light);
}

.badge-status-dark {
  background: var(--color-black-elevated);
  border-color: var(--color-gray-800);
  color: var(--color-gray-200);
}

.status-indicator {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--color-black);
}

.status-indicator-white {
  background-color: var(--color-white);
}

/* 核心指标微件 */
.stats-triad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 16px;
}

.stat-box {
  background: var(--color-gray-100);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 12px;
  text-align: center;
}

.stat-box-val {
  font-size: 1.375rem;
  font-weight: 800;
  color: var(--color-black);
  line-height: 1.1;
}

.stat-box-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-top: 4px;
}

/* 协议药丸微件 */
.protocol-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.chip-item {
  display: inline-block;
  padding: 6px 12px;
  border-radius: var(--radius-full);
  font-size: 0.8125rem;
  font-weight: 600;
  background: var(--color-black-elevated);
  border: 1px solid var(--color-gray-800);
  color: var(--color-white);
}

/* ==========================================================================
   Core Advantages (3-6 Cards)
   ========================================================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-xl);
  padding: 36px 28px;
  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
  position: relative;
  display: flex;
  flex-direction: column;
}

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

.feature-icon-wrapper {
  width: 54px;
  height: 54px;
  border-radius: var(--radius-lg);
  background: var(--color-black);
  color: var(--color-white);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
  flex-shrink: 0;
}

.feature-icon-wrapper svg {
  width: 26px;
  height: 26px;
  stroke: var(--color-white);
  fill: none;
}

.feature-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.feature-text {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.65;
  flex-grow: 1;
}

.feature-footer-tag {
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px dashed var(--border-light);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 6px;
}

/* ==========================================================================
   Streaming & AI Support Section
   ========================================================================== */
.streaming-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.support-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-xl);
  padding: 36px;
  box-shadow: var(--shadow-sm);
}

.panel-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 24px;
}

.panel-icon-circle {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-gray-100);
  border: 1.5px solid var(--color-black);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: 800;
}

.panel-title {
  font-size: 1.375rem;
  font-weight: 800;
  color: var(--color-black);
  letter-spacing: -0.02em;
}

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

.service-badges-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-bottom: 24px;
}

.service-badge-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-radius: var(--radius-md);
  background: var(--color-gray-100);
  border: 1px solid var(--border-subtle);
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}

.service-badge-card:hover {
  background: var(--color-white);
  border-color: var(--color-black);
}

.badge-abbr {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: var(--color-black);
  color: var(--color-white);
  font-size: 0.75rem;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.badge-info-name {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--color-black);
  line-height: 1.2;
}

.badge-info-status {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.support-disclaimer {
  padding: 14px 18px;
  border-radius: var(--radius-md);
  background: var(--color-gray-200);
  border-left: 3px solid var(--color-black);
  font-size: 0.8125rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

/* ==========================================================================
   Pricing Table Section
   ========================================================================== */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1.5px solid var(--border-light);
  border-radius: var(--radius-xl);
  padding: 40px 32px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

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

.pricing-card.popular {
  border-color: var(--color-black);
  background: var(--color-white);
  box-shadow: var(--shadow-md);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-black);
  color: var(--color-white);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  padding: 4px 16px;
  border-radius: var(--radius-full);
}

.plan-header {
  margin-bottom: 24px;
}

.plan-name {
  font-size: 1.375rem;
  font-weight: 800;
  color: var(--color-black);
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.plan-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
  min-height: 42px;
}

.plan-pricing-box {
  display: flex;
  align-items: baseline;
  gap: 4px;
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-light);
}

.price-currency {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-black);
}

.price-amount {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--color-black);
}

.price-cycle {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-muted);
}

.plan-features-list {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 32px;
}

.plan-feature-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.plan-check-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  stroke: var(--color-black);
  margin-top: 2px;
}

.plan-action {
  margin-top: auto;
}

.plan-action .btn {
  width: 100%;
}

/* ==========================================================================
   FAQ Section (Accordion)
   ========================================================================== */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  overflow: hidden;
  transition: border-color var(--transition-fast);
}

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

.faq-question-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 22px 28px;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--text-primary);
  text-align: left;
  transition: background-color var(--transition-fast);
}

.faq-toggle-icon {
  width: 20px;
  height: 20px;
  stroke: var(--color-black);
  transition: transform var(--transition-base);
  flex-shrink: 0;
}

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

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-smooth), padding var(--transition-smooth);
  padding: 0 28px;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.faq-item.active .faq-answer {
  max-height: 400px;
  padding: 0 28px 24px 28px;
}

/* ==========================================================================
   Floating Chapter Navigation (上下章节箭头)
   ========================================================================== */
.floating-chapter-nav {
  position: fixed;
  right: 28px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 99;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 8px;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-md);
  transition: opacity var(--transition-base), transform var(--transition-base);
}

.chapter-nav-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-white);
  border: 1px solid var(--border-light);
  color: var(--color-black);
  transition: all var(--transition-fast);
}

.chapter-nav-btn:hover:not(:disabled) {
  background-color: var(--color-black);
  color: var(--color-white);
  border-color: var(--color-black);
  transform: scale(1.08);
}

.chapter-nav-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
  pointer-events: none;
}

.chapter-nav-btn svg {
  width: 18px;
  height: 18px;
  stroke: currentColor;
  stroke-width: 2.2;
}

.chapter-indicator-text {
  font-size: 0.6875rem;
  font-weight: 700;
  color: var(--text-muted);
  writing-mode: vertical-rl;
  text-orientation: mixed;
  padding: 4px 0;
  letter-spacing: 0.1em;
}

/* ==========================================================================
   Footer (Strictly 4 Links)
   ========================================================================== */
.site-footer {
  margin-top: auto;
  background-color: var(--color-black);
  color: var(--color-white);
  padding: 64px 0 40px 0;
  border-top: 1px solid var(--color-gray-900);
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--color-gray-900);
  margin-bottom: 32px;
}

.footer-brand {
  max-width: 420px;
}

.footer-logo-text {
  font-family: var(--font-brand);
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--color-white);
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.footer-brand-desc {
  font-size: 0.875rem;
  color: var(--color-gray-500);
  line-height: 1.6;
}

/* 页脚严格只保留四个入口 */
.footer-links-grid {
  display: flex;
  align-items: center;
  gap: 28px;
  flex-wrap: wrap;
}

.footer-link-item {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-gray-300);
  transition: color var(--transition-fast);
  padding: 6px 0;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.footer-link-item:hover {
  color: var(--color-white);
  text-decoration: underline;
  text-underline-offset: 4px;
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8125rem;
  color: var(--color-gray-600);
}

/* ==========================================================================
   Article Pages & Secondary Pages (关于我们/条款/隐私/网站地图)
   ========================================================================== */
.page-hero {
  padding: 64px 0 48px 0;
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-light);
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.breadcrumb-separator {
  color: var(--color-gray-400);
}

.breadcrumb-active {
  color: var(--text-primary);
  font-weight: 600;
}

.content-article-body {
  padding: 64px 0 96px 0;
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--color-gray-800);
}

.content-article-body h2 {
  font-size: 1.625rem;
  font-weight: 800;
  color: var(--color-black);
  margin: 48px 0 20px 0;
  letter-spacing: -0.02em;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-light);
}

.content-article-body h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-black);
  margin: 32px 0 14px 0;
}

.content-article-body p {
  margin-bottom: 20px;
}

.content-article-body ul, .content-article-body ol {
  margin: 0 0 24px 24px;
  list-style: disc;
}

.content-article-body ol {
  list-style: decimal;
}

.content-article-body li {
  margin-bottom: 8px;
}

.content-article-body blockquote {
  margin: 28px 0;
  padding: 18px 24px;
  border-left: 4px solid var(--color-black);
  background: var(--bg-secondary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.article-promo-box {
  margin: 48px 0;
  padding: 32px;
  border: 2px solid var(--color-black);
  border-radius: var(--radius-xl);
  background: var(--bg-card);
  box-shadow: var(--shadow-md);
  text-align: center;
}

.article-promo-title {
  font-size: 1.375rem;
  font-weight: 800;
  margin-bottom: 10px;
  color: var(--color-black);
}

.article-promo-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

/* 文章列表网格 */
.articles-index-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  margin-top: 48px;
}

.article-summary-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-xl);
  padding: 28px;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
}

.article-summary-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-black);
}

.article-meta-row {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-bottom: 14px;
}

.article-tag-badge {
  padding: 2px 10px;
  border-radius: var(--radius-full);
  background: var(--color-gray-200);
  color: var(--color-black);
  font-weight: 700;
  font-size: 0.75rem;
}

.article-card-title {
  font-size: 1.1875rem;
  font-weight: 800;
  color: var(--color-black);
  line-height: 1.4;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.article-card-title a:hover {
  text-decoration: underline;
}

.article-card-snippet {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-read-more {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--color-black);
  margin-top: auto;
}

.article-read-more:hover {
  gap: 10px;
}

/* ==========================================================================
   Responsive Media Queries
   ========================================================================== */
@media (max-width: 1024px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 48px;
  }
  
  .hero-visual {
    max-width: 520px;
    margin: 0 auto;
  }
  
  .dynamic-card-protocol {
    margin-left: 0;
  }
  
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }
  
  .streaming-grid {
    grid-template-columns: 1fr;
  }
  
  .articles-index-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --nav-height: 64px;
  }
  
  .section {
    padding: 64px 0;
  }
  
  .hero-title {
    font-size: 2.25rem;
  }
  
  .section-title {
    font-size: 1.75rem;
  }
  
  .mobile-menu-toggle {
    display: flex;
  }
  
  .nav-menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    width: 100%;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-light);
    flex-direction: column;
    align-items: flex-start;
    padding: 24px;
    gap: 18px;
    box-shadow: var(--shadow-lg);
    display: none;
  }
  
  .nav-menu.open {
    display: flex;
  }
  
  .nav-link {
    font-size: 1.0625rem;
    width: 100%;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .articles-index-grid {
    grid-template-columns: 1fr;
  }
  
  .footer-top {
    flex-direction: column;
    align-items: flex-start;
    gap: 32px;
  }
  
  .footer-bottom {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }
  
  .floating-chapter-nav {
    right: 12px;
    bottom: 24px;
    top: auto;
    transform: none;
    flex-direction: row;
    padding: 6px;
    background: rgba(255, 255, 255, 0.95);
  }
  
  .chapter-indicator-text {
    display: none;
  }
  
  .chapter-nav-btn {
    width: 36px;
    height: 36px;
  }
  
  .service-badges-grid {
    grid-template-columns: 1fr;
  }
}