/* ==========================================================================
   flybit 网络加速器 - 官方落地页与全站样式表
   设计美学：日式极简 (Japanese Minimalism) - 克制排版、自然纯净色系、安静留白与细腻质感
   ========================================================================== */

:root {
  /* 自然纯净色彩体系 (以和纸质感、深墨黑、松竹绿与琥珀为核心) */
  --bg-page: #FAF9F5;
  --bg-surface: #FFFFFF;
  --bg-subtle: #F3F1EC;
  --bg-card: #FFFFFF;
  --bg-glass: rgba(255, 255, 255, 0.82);
  
  --text-main: #1D1F21;
  --text-secondary: #585D64;
  --text-muted: #848A93;
  --text-light: #FAF9F5;
  
  --border-color: #E6E4DD;
  --border-light: rgba(0, 0, 0, 0.06);
  --border-focus: #2D5A46;
  
  --primary: #2D5A46;        /* 雅致松针/竹青绿 */
  --primary-hover: #214434;
  --primary-subtle: #EBF2ED;
  --primary-text: #234737;
  
  --accent: #C67D35;         /* 柿红/琥珀温润点缀 */
  --accent-subtle: #FBF4EC;
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.08);

  /* 粗圆体排版与系统字体栈：优先使用本地与系统粗圆字体 */
  --font-heading: system-ui, -apple-system, "PingFang SC Rounded", "Hiragino Maru Gothic ProN", "Yu Gothic Rounded", "Arial Rounded MT Bold", "Microsoft YaHei", sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --max-width: 1160px;
  --header-height: 72px;
  --transition: 0.22s cubic-bezier(0.16, 1, 0.3, 1);
}

/* 基础重置 */
*, *::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: var(--font-body);
  background-color: var(--bg-page);
  color: var(--text-main);
  line-height: 1.68;
  letter-spacing: 0.015em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 尊重减弱动态效果偏好 */
@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;
  }
}

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

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

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

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

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

/* ==========================================================================
   通用标签、按钮与微交互
   ========================================================================== */
.badge-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 14px;
  background-color: var(--primary-subtle);
  color: var(--primary-text);
  font-size: 0.84rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  letter-spacing: 0.02em;
}

.badge-amber {
  background-color: var(--accent-subtle);
  color: var(--accent);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: 0.96rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  transition: all var(--transition);
  cursor: pointer;
  min-height: 46px;
  text-align: center;
}

.btn-primary {
  background-color: var(--primary);
  color: var(--text-light);
  box-shadow: 0 4px 14px rgba(45, 90, 70, 0.22);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(45, 90, 70, 0.28);
}

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

.btn-secondary:hover {
  background-color: var(--bg-subtle);
  border-color: #D2CFCE;
  transform: translateY(-2px);
}

.btn-outline {
  border: 1px solid var(--border-color);
  background-color: transparent;
  color: var(--text-main);
}

.btn-outline:hover {
  background-color: var(--bg-surface);
  border-color: var(--primary);
  color: var(--primary);
}

/* ==========================================================================
   页眉 Header
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  background-color: var(--bg-glass);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-light);
  transition: background-color var(--transition), border-color var(--transition);
}

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

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--text-main);
  letter-spacing: -0.02em;
}

.brand-logo:hover {
  opacity: 0.92;
}

.brand-logo-img {
  width: 36px;
  height: 36px;
  border-radius: 10px;
}

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

.nav-link {
  font-size: 0.94rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 8px 4px;
  position: relative;
}

.nav-link:hover, .nav-link.active {
  color: var(--text-main);
}

.nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background-color: var(--primary);
  transition: width var(--transition);
  border-radius: 2px;
}

.nav-link:hover::after, .nav-link.active::after {
  width: 80%;
}

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

.nav-toggle {
  display: none;
  padding: 8px;
  border-radius: var(--radius-sm);
  color: var(--text-main);
}

/* ==========================================================================
   右侧章节切换箭头 (Chapter Navigator)
   ========================================================================== */
.chapter-nav-fixed {
  position: fixed;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 990;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 10px 6px;
  border-radius: 30px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
  transition: opacity var(--transition), transform var(--transition);
}

.chapter-nav-btn {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-surface);
  color: var(--text-main);
  border: 1px solid var(--border-light);
  transition: all var(--transition);
}

.chapter-nav-btn:hover:not(:disabled) {
  background: var(--primary);
  color: #FFFFFF;
  border-color: var(--primary);
  transform: scale(1.06);
}

.chapter-nav-btn:disabled,
.chapter-nav-btn[aria-disabled="true"] {
  opacity: 0.28;
  cursor: not-allowed;
  pointer-events: none;
  background: var(--bg-subtle);
  border-color: transparent;
}

.chapter-indicator {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  writing-mode: vertical-rl;
  text-orientation: mixed;
  padding: 4px 0;
  letter-spacing: 0.06em;
  user-select: none;
}

/* ==========================================================================
   主视觉 Hero Section
   ========================================================================== */
.hero-section {
  padding: 72px 0 64px 0;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 48px;
  align-items: center;
}

.hero-content {
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.hero-title {
  font-family: var(--font-heading);
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.025em;
  color: var(--text-main);
}

.hero-title .brand-accent {
  color: var(--primary);
  position: relative;
  display: inline-block;
}

.hero-title .brand-accent::after {
  content: "";
  position: absolute;
  bottom: 4px;
  left: 0;
  width: 100%;
  height: 8px;
  background: rgba(45, 90, 70, 0.12);
  z-index: -1;
  border-radius: 4px;
}

.hero-desc {
  font-size: 1.12rem;
  color: var(--text-secondary);
  line-height: 1.8;
  max-width: 560px;
}

.hero-cta-group {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 8px;
}

.hero-notes {
  display: flex;
  align-items: center;
  gap: 20px;
  font-size: 0.86rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.hero-notes span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* 桌面端动态交互图卡 (桌面端随机/画册感排列，手机端单栏上下排列) */
.hero-visual-cards {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.visual-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 22px 24px;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition), box-shadow var(--transition);
}

.visual-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.visual-card-primary {
  transform: rotate(-1deg);
  border-left: 4px solid var(--primary);
}

.visual-card-secondary {
  transform: rotate(1.2deg) translateX(12px);
  border-left: 4px solid var(--accent);
}

.card-header-flex {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.card-header-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 8px;
}

.pulse-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: #2E7D32;
  box-shadow: 0 0 0 3px rgba(46, 125, 50, 0.2);
}

.node-item-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.node-item-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.88rem;
  padding: 8px 12px;
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
}

.node-name {
  font-weight: 600;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 8px;
}

.node-ping {
  font-family: monospace;
  font-size: 0.82rem;
  color: var(--primary);
  font-weight: 700;
}

.speed-metric-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.speed-metric-box {
  background: var(--bg-subtle);
  padding: 12px 14px;
  border-radius: var(--radius-sm);
}

.speed-metric-num {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  font-family: var(--font-heading);
}

.speed-metric-label {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* ==========================================================================
   核心优势 Section
   ========================================================================== */
.section {
  padding: 84px 0;
  position: relative;
}

.section-header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 56px auto;
}

.section-eyebrow {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

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

.section-subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.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-lg);
  padding: 34px 28px;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

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

.feature-icon-box {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: var(--primary-subtle);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

.feature-title {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
}

.feature-desc {
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

/* ==========================================================================
   流媒体与 AI 支持 Section
   ========================================================================== */
.services-card-wrapper {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 44px;
  box-shadow: var(--shadow-sm);
}

.services-group-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.services-grid-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 36px;
}

.service-pill-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  background: var(--bg-subtle);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  transition: all var(--transition);
}

.service-pill-item:hover {
  background: var(--bg-surface);
  border-color: var(--border-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.service-pill-icon {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  background: #FFFFFF;
}

.service-pill-name {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text-main);
}

.service-pill-desc {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.service-disclaimer-box {
  background: var(--bg-page);
  border-left: 3px solid var(--primary);
  padding: 16px 20px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.68;
}

/* ==========================================================================
   套餐对比 Pricing Section
   ========================================================================== */
.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-lg);
  padding: 36px 30px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all var(--transition);
}

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

.pricing-card-featured {
  border: 2px solid var(--primary);
  box-shadow: var(--shadow-md);
  background: #FFFFFF;
}

.pricing-tag-ribbon {
  position: absolute;
  top: -13px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary);
  color: #FFFFFF;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  letter-spacing: 0.04em;
  white-space: nowrap;
}

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

.plan-desc {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 22px;
}

.plan-price-wrapper {
  display: flex;
  align-items: baseline;
  gap: 4px;
  margin-bottom: 26px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--border-light);
}

.plan-currency {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-main);
}

.plan-price {
  font-family: var(--font-heading);
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1;
}

.plan-cycle {
  font-size: 0.92rem;
  color: var(--text-muted);
}

.plan-features-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 13px;
  margin-bottom: 32px;
  flex-grow: 1;
}

.plan-feature-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.plan-feature-item svg {
  flex-shrink: 0;
  margin-top: 3px;
  color: var(--primary);
}

/* ==========================================================================
   常见问题 FAQ Section
   ========================================================================== */
.faq-list {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition);
}

.faq-item:hover {
  border-color: #D2CFCE;
}

.faq-question-btn {
  width: 100%;
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  text-align: left;
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  background: transparent;
}

.faq-icon-arrow {
  transition: transform var(--transition);
  color: var(--text-muted);
  flex-shrink: 0;
}

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

.faq-answer-content {
  padding: 0 24px 22px 24px;
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.75;
  display: none;
}

.faq-item.active .faq-answer-content {
  display: block;
}

/* ==========================================================================
   页脚 Footer
   ========================================================================== */
.site-footer {
  background: #18191B;
  color: #B5B9C0;
  padding: 64px 0 36px 0;
  margin-top: 80px;
  border-top: 1px solid #282A2E;
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 40px;
  border-bottom: 1px solid #2B2D31;
  flex-wrap: wrap;
  gap: 24px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: #FFFFFF;
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
}

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

.footer-link {
  color: #A0A5AE;
  font-size: 0.94rem;
  transition: color var(--transition);
}

.footer-link:hover {
  color: #FFFFFF;
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 28px;
  font-size: 0.85rem;
  color: #72767E;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-disclaimer-text {
  font-size: 0.82rem;
  color: #646870;
  line-height: 1.6;
  max-width: 680px;
}

/* ==========================================================================
   知识科普文章与独立页面样式 (Articles & Pages)
   ========================================================================== */
.page-hero {
  padding: 56px 0 36px 0;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-surface);
  margin-bottom: 48px;
}

.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.86rem;
  color: var(--text-muted);
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.breadcrumbs a {
  color: var(--text-secondary);
}

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

.page-title {
  font-family: var(--font-heading);
  font-size: 2.3rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1.3;
  margin-bottom: 14px;
}

.page-meta {
  display: flex;
  align-items: center;
  gap: 20px;
  font-size: 0.86rem;
  color: var(--text-muted);
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
  margin-bottom: 60px;
}

.article-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 30px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 16px;
  transition: all var(--transition);
}

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

.article-card-title {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.45;
}

.article-card:hover .article-card-title {
  color: var(--primary);
}

.article-card-excerpt {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  border-top: 1px solid var(--border-light);
  font-size: 0.84rem;
  color: var(--text-muted);
}

/* 文章正文排版 (Content Layout) */
.article-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 48px;
  align-items: start;
  margin-bottom: 80px;
}

.article-content {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 48px 44px;
  font-size: 1.05rem;
  line-height: 1.85;
  color: #2D3139;
}

.article-content h2 {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text-main);
  margin-top: 38px;
  margin-bottom: 18px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-light);
}

.article-content h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  margin-top: 26px;
  margin-bottom: 12px;
}

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

.article-content ul, .article-content ol {
  margin-bottom: 22px;
  padding-left: 24px;
}

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

.article-content blockquote {
  border-left: 3px solid var(--primary);
  background: var(--primary-subtle);
  padding: 16px 20px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 24px 0;
  font-size: 0.95rem;
  color: var(--primary-text);
}

.article-promo-box {
  background: #F4F7F5;
  border: 1px solid #D1DFD6;
  border-radius: var(--radius-md);
  padding: 24px;
  margin: 32px 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.article-sidebar {
  position: sticky;
  top: 96px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.sidebar-widget {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 26px 22px;
}

.sidebar-widget-title {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--text-main);
}

/* ==========================================================================
   移动端与响应式适配 (Mobile & Responsive)
   ========================================================================== */
@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 36px;
  }
  
  .hero-visual-cards {
    max-width: 520px;
  }
  
  .visual-card-secondary {
    transform: none;
  }
  
  .visual-card-primary {
    transform: none;
  }

  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }

  .article-layout {
    grid-template-columns: 1fr;
  }
  
  .article-sidebar {
    position: static;
  }
}

@media (max-width: 768px) {
  :root {
    --header-height: 64px;
  }

  .hero-section {
    padding: 36px 0 44px 0;
  }

  .hero-title {
    font-size: 2.2rem;
  }

  .hero-desc {
    font-size: 1rem;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .articles-grid {
    grid-template-columns: 1fr;
  }

  .services-card-wrapper {
    padding: 24px 20px;
  }

  .article-content {
    padding: 28px 20px;
  }

  /* 移动端导航菜单 */
  .main-nav {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-color);
    flex-direction: column;
    padding: 20px 24px;
    gap: 16px;
    box-shadow: var(--shadow-md);
  }

  .main-nav.active {
    display: flex;
  }

  .nav-toggle {
    display: block;
  }

  /* 移动端右侧浮动箭头调整，避免遮挡正文与按钮 */
  .chapter-nav-fixed {
    right: 14px;
    bottom: 24px;
    top: auto;
    transform: none;
    flex-direction: row;
    padding: 6px 10px;
    border-radius: var(--radius-full);
  }

  .chapter-indicator {
    writing-mode: horizontal-tb;
    padding: 0 6px;
  }

  .footer-top {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-nav {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}