/* ===================================================================
   WgetCloud — Monolithic Linear Precision
   Ultra-minimal developer-first architecture | Pitch-black & Zinc Grey
   Hairline 0.5px borders | Border-Beam | Spring Glider | Inset Flash
   =================================================================== */

:root {
  /* 默认白天模式 (Light Linear Precision) */
  --bg-primary: #fafafa;
  --bg-surface: #ffffff;
  --bg-surface-elevated: #f4f4f6;
  --bg-surface-hover: #ececee;
  --bg-header: rgba(250, 250, 250, 0.92);
  
  --border-hairline: #e4e4e7;
  --border-subtle: #d4d4d8;
  --border-focus: #18181b;
  --beam-color: rgba(0, 0, 0, 0.45);

  --text-primary: #09090b;
  --text-secondary: #52525b;
  --text-muted: #71717a;
  --text-accent: #2563eb;
  --text-mono: #0284c7;

  --accent-primary: #18181b;
  --accent-hover: #27272a;
  --accent-text: #ffffff;
  --accent-cyan: #0284c7;
  --accent-emerald: #10b981;
  --accent-amber: #f59e0b;

  --pill-active-bg: #ffffff;
  --pill-active-shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --container-max: 1220px;

  --transition-fast: 0.15s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-normal: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-spring: 0.35s cubic-bezier(0.175, 0.885, 0.32, 1.15);
}

/* 极致开发者黑夜模式 (Ultra-minimal developer-first dark mode) */
[data-theme="dark"] {
  --bg-primary: #000000;
  --bg-surface: #0c0d0e;
  --bg-surface-elevated: #131518;
  --bg-surface-hover: #191c20;
  --bg-header: rgba(0, 0, 0, 0.88);

  --border-hairline: #1f2328;
  --border-subtle: #2d333b;
  --border-focus: #e6edf3;
  --beam-color: rgba(255, 255, 255, 0.85);

  --text-primary: #f0f6fc;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --text-accent: #58a6ff;
  --text-mono: #38bdf8;

  --accent-primary: #f0f6fc;
  --accent-hover: #ffffff;
  --accent-text: #000000;
  --accent-cyan: #38bdf8;
  --accent-emerald: #238636;
  --accent-amber: #d29922;

  --pill-active-bg: #1c2128;
  --pill-active-shadow: 0 0 0 1px #30363d, 0 4px 12px rgba(0,0,0,0.5);
}

/* ===================================================================
   基础排版与重置
   =================================================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

ul, ol {
  list-style: none;
}

.mono {
  font-family: var(--font-mono);
  letter-spacing: -0.015em;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===================================================================
   顶部导航栏 (Navbar)
   =================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-header);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-hairline);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 1.25rem;
  font-weight: 750;
  letter-spacing: -0.03em;
  color: var(--text-primary);
}

.brand-glyph {
  width: 28px;
  height: 28px;
  border: 1px solid var(--border-hairline);
  background: var(--bg-surface-elevated);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
}

.brand-dot {
  color: var(--text-accent);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.nav-link {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 0.4rem 0.6rem;
  border-radius: 6px;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

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

.nav-link.nav-badge-link {
  color: var(--text-accent);
  border: 1px solid rgba(56, 189, 248, 0.25);
  background: rgba(56, 189, 248, 0.06);
}

.nav-link.nav-badge-link:hover {
  background: rgba(56, 189, 248, 0.15);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* 昼夜切换按钮 */
.theme-toggle-btn {
  width: 38px;
  height: 38px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  color: var(--text-secondary);
  position: relative;
  overflow: hidden;
  transition: all var(--transition-fast);
}

.theme-toggle-btn:hover {
  color: var(--text-primary);
  border-color: var(--border-focus);
}

.theme-toggle-btn svg {
  width: 17px;
  height: 17px;
  transition: transform var(--transition-normal), opacity var(--transition-normal);
}

.theme-toggle-btn .sun-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

.theme-toggle-btn .moon-icon {
  position: absolute;
  opacity: 0;
  transform: rotate(-90deg) scale(0.5);
}

[data-theme="dark"] .theme-toggle-btn .sun-icon {
  opacity: 0;
  transform: rotate(90deg) scale(0.5);
}

[data-theme="dark"] .theme-toggle-btn .moon-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
  display: none;
  width: 38px;
  height: 38px;
  border-radius: 8px;
  border: 1px solid var(--border-hairline);
  background: var(--bg-surface-elevated);
  color: var(--text-primary);
  align-items: center;
  justify-content: center;
}

/* ===================================================================
   通用按钮规范与微妙内发光交互 (Subtle Inset Flash on Click)
   =================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.65rem 1.4rem;
  border-radius: 8px;
  transition: all var(--transition-fast);
  text-align: center;
  white-space: nowrap;
  outline: none;
  position: relative;
}

.btn:active {
  box-shadow: inset 0 0 0 1px var(--beam-color), inset 0 0 8px rgba(255, 255, 255, 0.25) !important;
  transform: scale(0.985);
}

.btn-primary {
  background: var(--accent-primary);
  color: var(--accent-text) !important;
  border: 1px solid var(--accent-primary);
}

.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--border-focus);
}

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

.btn-secondary:hover {
  background: var(--bg-surface-elevated);
  border-color: var(--border-subtle);
}

.btn-sm {
  padding: 0.45rem 0.9rem;
  font-size: 0.825rem;
}

.btn-lg {
  padding: 0.8rem 1.8rem;
  font-size: 0.98rem;
}

.btn-block {
  width: 100%;
}

/* ===================================================================
   主视觉区 (Hero Section) — Asymmetric Two-Column Grid
   =================================================================== */
.hero-section {
  padding: 5.5rem 0 4rem;
  border-bottom: 1px solid var(--border-hairline);
  position: relative;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 3rem;
  align-items: center;
}

.hero-left {
  display: flex;
  flex-direction: column;
}

.hero-badge-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.hero-system-status {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.25rem 0.65rem;
  border-radius: 6px;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.status-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-emerald);
  box-shadow: 0 0 8px rgba(16, 185, 129, 0.8);
}

.hero-headline {
  font-size: clamp(2rem, 3.6vw, 3.2rem);
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.035em;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
}

.hero-subheadline {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 1.75rem;
  max-width: 580px;
}

.hero-metrics-stack {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  margin-bottom: 2rem;
  padding: 0.9rem 1.1rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 8px;
  border-left: 3px solid var(--accent-cyan);
}

.metric-line {
  font-size: 0.84rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.metric-key {
  color: var(--text-muted);
  min-width: 130px;
}

.metric-val {
  color: var(--text-primary);
  font-weight: 600;
}

.metric-val.green {
  color: var(--accent-emerald);
}

.metric-val.cyan {
  color: var(--accent-cyan);
}

.hero-cta-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

/* Hero 右侧：实时动态 SVG 折线遥测容器 */
.hero-right-telemetry {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 16px 36px -12px rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] .hero-right-telemetry {
  box-shadow: 0 16px 36px -12px rgba(0, 0, 0, 0.85);
}

.telemetry-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--border-hairline);
  background: var(--bg-surface-elevated);
}

.telemetry-title-group {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
}

.live-indicator-dot {
  width: 6px;
  height: 6px;
  background: var(--accent-emerald);
  border-radius: 50%;
  animation: telemetryPulse 1.8s infinite;
}

@keyframes telemetryPulse {
  0% { transform: scale(0.9); opacity: 0.5; }
  50% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(0.9); opacity: 0.5; }
}

.telemetry-stats-bar {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--border-hairline);
  background: var(--bg-surface);
}

.stat-cell {
  display: flex;
  flex-direction: column;
}

.stat-cell-label {
  font-size: 0.72rem;
  color: var(--text-muted);
  text-transform: uppercase;
}

.stat-cell-value {
  font-size: 0.96rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 0.15rem;
}

.telemetry-chart-viewport {
  padding: 1.25rem;
  position: relative;
  background: var(--bg-surface);
}

.svg-telemetry-chart {
  width: 100%;
  height: 160px;
  overflow: visible;
}

.grid-line {
  stroke: var(--border-hairline);
  stroke-dasharray: 2 3;
  stroke-width: 0.8;
}

.chart-line {
  fill: none;
  stroke: var(--accent-cyan);
  stroke-width: 1.75;
  stroke-linecap: round;
  stroke-linejoin: round;
  filter: drop-shadow(0 2px 4px rgba(2, 132, 199, 0.35));
}

.chart-area {
  fill: url(#telemetryGradient);
  opacity: 0.25;
}

.chart-ping-dot {
  fill: var(--accent-cyan);
  stroke: var(--bg-surface);
  stroke-width: 2;
  animation: pingPulse 1.8s infinite;
}

@keyframes pingPulse {
  0% { r: 3.5; }
  50% { r: 5.5; }
  100% { r: 3.5; }
}

.telemetry-footer-status {
  padding: 0.65rem 1.25rem;
  font-size: 0.76rem;
  color: var(--text-muted);
  background: var(--bg-surface-elevated);
  border-top: 1px solid var(--border-hairline);
  display: flex;
  justify-content: space-between;
}

/* ===================================================================
   Border-Beam Hover 交互核心规范
   =================================================================== */
.border-beam-card {
  position: relative;
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 12px;
  overflow: hidden;
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.border-beam-card::after {
  content: "";
  position: absolute;
  inset: -1px;
  border-radius: 12px;
  padding: 1px;
  background: conic-gradient(
    from var(--beam-angle, 0deg) at 50% 50%,
    transparent 0deg,
    transparent 65deg,
    var(--beam-color) 90deg,
    transparent 115deg,
    transparent 360deg
  );
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: 0;
  transition: opacity 0.35s ease;
  pointer-events: none;
  z-index: 2;
}

@property --beam-angle {
  syntax: '<angle>';
  initial-value: 0deg;
  inherits: false;
}

.border-beam-card:hover {
  transform: translateY(-2px);
  border-color: var(--border-subtle);
}

.border-beam-card:hover::after {
  opacity: 1;
  animation: beamSpin 3s linear infinite;
}

@keyframes beamSpin {
  0% { --beam-angle: 0deg; }
  100% { --beam-angle: 360deg; }
}

/* ===================================================================
   板块基础布局 (Sections)
   =================================================================== */
.section {
  padding: 5rem 0;
  border-bottom: 1px solid var(--border-hairline);
}

.section-header {
  max-width: 680px;
  margin: 0 auto 3.5rem;
  text-align: center;
}

.section-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-accent);
  margin-bottom: 0.5rem;
}

.section-title {
  font-size: clamp(1.8rem, 2.8vw, 2.4rem);
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.03em;
  margin-bottom: 0.85rem;
}

.section-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

/* ===================================================================
   核心优势卡片
   =================================================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.feature-box {
  padding: 2.2rem 1.8rem;
  display: flex;
  flex-direction: column;
}

.feature-tag-code {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

.feature-heading {
  font-size: 1.25rem;
  font-weight: 750;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.feature-body {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.feature-specs-list {
  border-top: 1px solid var(--border-hairline);
  padding-top: 1.1rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.spec-line {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.84rem;
  color: var(--text-secondary);
}

.spec-bullet {
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent-cyan);
}

/* ===================================================================
   Direct Tab Scrubbing 节点遥测滑动胶囊
   =================================================================== */
.telemetry-explorer-panel {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 14px;
  padding: 2rem;
}

.region-tabs-nav {
  position: relative;
  display: inline-flex;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 10px;
  padding: 4px;
  margin-bottom: 2rem;
  gap: 4px;
  overflow-x: auto;
  max-width: 100%;
}

.region-tab-btn {
  position: relative;
  z-index: 2;
  padding: 0.55rem 1.2rem;
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--text-secondary);
  border-radius: 7px;
  transition: color var(--transition-fast);
  white-space: nowrap;
}

.region-tab-btn:hover,
.region-tab-btn.active {
  color: var(--text-primary);
}

.tab-glider {
  position: absolute;
  top: 4px;
  left: 4px;
  height: calc(100% - 8px);
  background: var(--pill-active-bg);
  box-shadow: var(--pill-active-shadow);
  border-radius: 7px;
  z-index: 1;
  pointer-events: none;
  transition: transform var(--transition-spring), width var(--transition-spring);
}

.region-data-display {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 1.5rem;
  padding: 1.5rem;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 10px;
}

.data-metric-block {
  display: flex;
  flex-direction: column;
}

.data-metric-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
}

.data-metric-number {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 0.2rem 0;
  letter-spacing: -0.02em;
}

.data-metric-sub {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* ===================================================================
   流媒体图卡 & AI 支持图卡
   =================================================================== */
.capability-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.75rem;
}

.capability-card {
  padding: 2.4rem;
  display: flex;
  flex-direction: column;
}

.capability-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent-cyan);
  margin-bottom: 1rem;
}

.capability-title {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  letter-spacing: -0.025em;
}

.capability-desc {
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 1.75rem;
}

.service-pills-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 2rem;
}

.service-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.85rem;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 6px;
  font-size: 0.84rem;
  font-weight: 500;
  color: var(--text-primary);
}

.service-pill-indicator {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-emerald);
}

/* ===================================================================
   套餐价格对比表
   =================================================================== */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
}

.pricing-plan-card {
  padding: 2.4rem 2rem;
  display: flex;
  flex-direction: column;
  position: relative;
}

.pricing-plan-card.recommended {
  border-color: var(--accent-cyan);
  background: var(--bg-surface);
}

.recommended-pill {
  position: absolute;
  top: -12px;
  left: 2rem;
  background: var(--accent-primary);
  color: var(--accent-text);
  font-size: 0.74rem;
  font-weight: 700;
  padding: 0.2rem 0.85rem;
  border-radius: 20px;
  border: 1px solid var(--border-focus);
  letter-spacing: 0.04em;
}

.plan-tier-name {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
}

.plan-tier-summary {
  font-size: 0.86rem;
  color: var(--text-muted);
  min-height: 42px;
}

.plan-price-block {
  margin: 1.5rem 0 1.25rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-hairline);
}

.price-num-row {
  display: flex;
  align-items: baseline;
  gap: 0.3rem;
}

.price-symbol {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
}

.price-number {
  font-size: 2.5rem;
  font-weight: 850;
  color: var(--text-primary);
  letter-spacing: -0.03em;
  line-height: 1;
}

.price-cycle {
  font-size: 0.88rem;
  color: var(--text-muted);
}

.price-billing-alt {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-top: 0.4rem;
}

.plan-perks-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 2rem;
  flex-grow: 1;
}

.perk-item {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.perk-check {
  color: var(--accent-emerald);
  font-weight: bold;
}

.perk-cross {
  color: var(--text-muted);
  opacity: 0.5;
}

/* ===================================================================
   用户口碑评价 (Testimonials)
   =================================================================== */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.testimonial-box {
  padding: 1.8rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.testimonial-quote {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 1.5rem;
}

.author-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  border-top: 1px solid var(--border-hairline);
  padding-top: 1rem;
}

.author-monogram {
  width: 36px;
  height: 36px;
  border-radius: 6px;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--text-primary);
}

.author-info-col {
  display: flex;
  flex-direction: column;
}

.author-title-name {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
}

.author-title-desc {
  font-size: 0.76rem;
  color: var(--text-muted);
}

/* ===================================================================
   常见问题解答 (FAQ Accordion)
   =================================================================== */
.faq-wrap {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.faq-node {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 10px;
  overflow: hidden;
  transition: border-color var(--transition-fast);
}

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

.faq-trigger {
  width: 100%;
  padding: 1.25rem 1.4rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  text-align: left;
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--text-primary);
}

.faq-symbol {
  width: 18px;
  height: 18px;
  color: var(--text-muted);
  transition: transform var(--transition-fast);
}

.faq-node.active .faq-symbol {
  transform: rotate(45deg);
  color: var(--accent-cyan);
}

.faq-collapse-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-normal), padding var(--transition-normal);
  padding: 0 1.4rem;
}

.faq-node.active .faq-collapse-body {
  max-height: 380px;
  padding: 0 1.4rem 1.25rem;
}

.faq-collapse-body p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

/* ===================================================================
   页脚规范 (Footer) — 严格保留仅4个指定标题
   =================================================================== */
.site-footer {
  border-top: 1px solid var(--border-hairline);
  background: var(--bg-surface);
  padding: 3rem 0;
}

.footer-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.75rem;
}

.footer-link {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

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

.footer-legal-copy {
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-hairline);
  padding-top: 1.5rem;
  max-width: 580px;
  margin: 0 auto;
}

/* ===================================================================
   SEO 长篇科普文章专用排版系统 (Article Reading System)
   =================================================================== */
.subpage-container {
  max-width: 920px;
  margin: 3rem auto 5rem;
  padding: 0 1.5rem;
}

.subpage-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 12px;
  padding: 3rem 2.5rem;
}

.subpage-header {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-hairline);
}

.subpage-title {
  font-size: clamp(1.8rem, 3.2vw, 2.35rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin: 0.5rem 0 0.85rem;
  line-height: 1.25;
}

.subpage-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: 0.82rem;
  color: var(--text-muted);
  align-items: center;
}

.meta-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
}

/* 文章目录导航框 (Table of Contents) */
.article-toc {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-left: 3px solid var(--accent-cyan);
  border-radius: 8px;
  padding: 1.35rem 1.6rem;
  margin: 2rem 0 2.5rem;
}

.toc-heading {
  font-size: 0.95rem;
  font-weight: 750;
  color: var(--text-primary);
  margin-bottom: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.toc-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.toc-item a {
  font-size: 0.88rem;
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
}

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

.toc-bullet {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* 正文排版 */
.article-content {
  color: var(--text-secondary);
  line-height: 1.85;
  font-size: 1rem;
}

.article-content h2 {
  font-size: 1.45rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 2.75rem 0 1rem;
  letter-spacing: -0.025em;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-hairline);
}

.article-content h3 {
  font-size: 1.18rem;
  font-weight: 750;
  color: var(--text-primary);
  margin: 1.75rem 0 0.75rem;
  letter-spacing: -0.015em;
}

.article-content p {
  margin-bottom: 1.25rem;
}

.article-content ul, .article-content ol {
  margin-bottom: 1.35rem;
  padding-left: 1.5rem;
}

.article-content ul li {
  list-style-type: disc;
  margin-bottom: 0.5rem;
}

.article-content ol li {
  list-style-type: decimal;
  margin-bottom: 0.5rem;
}

.article-content strong {
  color: var(--text-primary);
  font-weight: 700;
}

.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.75rem 0;
  font-size: 0.88rem;
}

.article-content th, .article-content td {
  padding: 0.75rem 1rem;
  border: 1px solid var(--border-hairline);
  text-align: left;
}

.article-content th {
  background: var(--bg-surface-elevated);
  color: var(--text-primary);
  font-weight: 700;
}

.article-content td {
  background: var(--bg-surface);
}

/* 文章内置 CTA 行动横幅 */
.article-cta-box {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 10px;
  padding: 1.75rem;
  margin: 2.5rem 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.article-cta-box h4 {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.article-cta-box p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  max-width: 580px;
  margin: 0 auto 1.25rem;
}

/* 文章 FAQ 问答区块 */
.article-faq-section {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-hairline);
}

.article-faq-item {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 8px;
  padding: 1.25rem 1.4rem;
  margin-bottom: 1rem;
}

.article-faq-question {
  font-size: 1.02rem;
  font-weight: 750;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

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

/* 相关阅读推荐列表 (Related Reading Silo) */
.related-posts-section {
  margin-top: 3.5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-hairline);
}

.related-posts-heading {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
}

.related-posts-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.related-post-card {
  padding: 1.25rem 1.4rem;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 8px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-fast);
}

.related-post-card:hover {
  border-color: var(--border-focus);
  transform: translateY(-2px);
}

.related-post-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
  line-height: 1.45;
}

.related-post-desc {
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.55;
}

/* 推荐资讯列表网格 */
.insights-feed-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  margin-top: 1.75rem;
}

.insight-item-box {
  padding: 1.85rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: border-color var(--transition-fast), transform var(--transition-fast);
}

.insight-item-box:hover {
  border-color: var(--border-subtle);
  transform: translateY(-2px);
}

.insight-item-date {
  font-size: 0.78rem;
  color: var(--text-accent);
  margin-bottom: 0.5rem;
}

.insight-item-title {
  font-size: 1.15rem;
  font-weight: 750;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
  letter-spacing: -0.02em;
  line-height: 1.4;
}

.insight-item-title a:hover {
  color: var(--text-accent);
}

.insight-item-excerpt {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.25rem;
}

.insight-item-readmore {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--text-accent);
}

.insight-item-readmore:hover {
  text-decoration: underline;
}

.back-home-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.88rem;
  color: var(--text-secondary);
  font-weight: 600;
  margin-bottom: 1.5rem;
  transition: color var(--transition-fast);
}

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

/* ===================================================================
   响应式媒体查询 (@media)
   =================================================================== */
@media (max-width: 1024px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }

  .features-grid,
  .pricing-grid,
  .testimonials-grid,
  .insights-feed-grid,
  .related-posts-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .features-grid .feature-box:last-child,
  .pricing-grid .pricing-plan-card:last-child,
  .testimonials-grid .testimonial-box:last-child {
    grid-column: span 2;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    width: 100%;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-hairline);
    flex-direction: column;
    padding: 1.25rem 1.5rem;
    gap: 0.6rem;
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.2);
  }

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

  .mobile-menu-btn {
    display: flex;
  }

  .hero-section {
    padding: 3.5rem 0 2.5rem;
  }

  .hero-headline {
    font-size: 2.15rem;
  }

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

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

  .features-grid,
  .features-grid .feature-box:last-child,
  .capability-grid,
  .pricing-grid,
  .pricing-plan-card:last-child,
  .testimonials-grid,
  .testimonials-grid .testimonial-box:last-child,
  .region-data-display,
  .insights-feed-grid,
  .related-posts-grid {
    grid-template-columns: 1fr;
    grid-column: auto;
  }

  .footer-nav {
    flex-direction: column;
    gap: 1.25rem;
  }

  .subpage-card {
    padding: 2rem 1.25rem;
  }

  .subpage-title {
    font-size: 1.65rem;
  }
}