/* ==========================================================================
   ImmTelecom (immtelecom.casa) - 官方网站核心样式表
   Pure Native CSS - 0外部重型框架 · 极致秒开与高转化体验
   ========================================================================== */

:root {
  /* 品牌深邃科技基底配色 */
  --bg-primary: #030712;
  --bg-secondary: #0b1329;
  --bg-tertiary: #111e38;
  --bg-card: rgba(15, 23, 42, 0.72);
  --bg-card-hover: rgba(22, 36, 68, 0.88);
  --bg-glass: rgba(11, 19, 41, 0.82);
  
  --border-color: rgba(56, 189, 248, 0.16);
  --border-hover: rgba(56, 189, 248, 0.45);
  --border-glow: rgba(0, 242, 254, 0.65);
  
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  
  /* 电光青与量子紫核心品牌色板 */
  --cyan-primary: #00f2fe;
  --cyan-hover: #38bdf8;
  --cyan-light: #7dd3fc;
  --cyan-gradient: linear-gradient(135deg, #00f2fe 0%, #4facfe 50%, #0284c7 100%);
  --cyan-glow: rgba(0, 242, 254, 0.35);

  --purple-gradient: linear-gradient(135deg, #c084fc 0%, #9333ea 50%, #6b21a8 100%);
  --gold-gradient: linear-gradient(135deg, #fde047 0%, #eab308 55%, #ca8a04 100%);
  --emerald-gradient: linear-gradient(135deg, #34d399 0%, #10b981 100%);
  
  --accent-emerald: #10b981;
  --accent-gold: #f59e0b;
  --accent-indigo: #6366f1;
  --accent-rose: #f43f5e;
  
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.35);
  --shadow-card: 0 12px 36px -10px rgba(0, 0, 0, 0.75);
  --shadow-glow: 0 0 35px rgba(0, 242, 254, 0.3);
  --shadow-purple-glow: 0 0 35px rgba(147, 51, 234, 0.3);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", Consolas, Monaco, "Courier New", monospace;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --transition: all 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  background-color: var(--bg-primary);
  color: var(--text-main);
}

body {
  font-family: var(--font-sans);
  line-height: 1.68;
  overflow-x: hidden;
  position: relative;
  background-color: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
}

/* 容器规范 */
.container {
  width: 100%;
  max-width: 1280px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
  position: relative;
  z-index: 2;
}

/* ==========================================================================
   动态背景系统 (Dynamic Canvas + Ambient Glows)
   ========================================================================== */
.dynamic-bg-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

#bg-canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.95;
  display: block;
  z-index: 1;
}

.ambient-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(120px);
  will-change: transform;
  pointer-events: none;
  z-index: 0;
  opacity: 0.25;
  animation: floatOrb 22s ease-in-out infinite alternate;
}

.ambient-orb-1 {
  width: 550px;
  height: 550px;
  background: radial-gradient(circle, #00f2fe 0%, rgba(0, 242, 254, 0) 70%);
  top: -150px;
  left: 10%;
}

.ambient-orb-2 {
  width: 650px;
  height: 650px;
  background: radial-gradient(circle, #9333ea 0%, rgba(147, 51, 234, 0) 70%);
  top: 40%;
  right: -100px;
  animation-duration: 28s;
  animation-delay: -5s;
}

.ambient-orb-3 {
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, #10b981 0%, rgba(16, 185, 129, 0) 70%);
  bottom: 5%;
  left: 5%;
  animation-duration: 25s;
  animation-delay: -10s;
}

@keyframes floatOrb {
  0% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(40px, 30px) scale(1.08); }
  100% { transform: translate(-30px, -20px) scale(0.95); }
}

/* ==========================================================================
   页面顶部导航 (Site Header & Top Navigation)
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  background: rgba(3, 7, 18, 0.75);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(56, 189, 248, 0.12);
  transition: var(--transition);
}

.site-header.scrolled {
  background: rgba(3, 7, 18, 0.94);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.6);
  border-bottom-color: rgba(56, 189, 248, 0.25);
}

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

/* 左侧品牌 Logo */
.site-logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  transition: var(--transition);
}

.site-logo:hover {
  transform: translateY(-1px);
}

.site-logo img {
  height: 44px;
  width: auto;
  display: block;
}

/* 中间导航链接 */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-link {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.96rem;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
  padding: 6px 0;
}

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

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--cyan-gradient);
  transition: width 0.25s ease;
  border-radius: 2px;
}

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

/* 导航右侧 CTA 操作 */
.nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.mobile-menu-toggle {
  display: none;
  background: none;
  border: 1px solid rgba(56, 189, 248, 0.25);
  color: var(--text-main);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 1.25rem;
}

/* ==========================================================================
   按钮组件系统 (Buttons System)
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 26px;
  border-radius: var(--radius-full);
  font-size: 0.96rem;
  font-weight: 600;
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
  border: 1px solid transparent;
  white-space: nowrap;
}

.btn-primary {
  background: var(--cyan-gradient);
  color: #030712;
  box-shadow: 0 4px 20px var(--cyan-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(0, 242, 254, 0.5);
  filter: brightness(1.1);
}

.btn-secondary {
  background: var(--purple-gradient);
  color: #ffffff;
  box-shadow: 0 4px 20px var(--shadow-purple-glow);
}

.btn-secondary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(147, 51, 234, 0.5);
  filter: brightness(1.1);
}

.btn-outline {
  background: rgba(15, 23, 42, 0.6);
  color: var(--text-main);
  border-color: rgba(56, 189, 248, 0.35);
  backdrop-filter: blur(8px);
}

.btn-outline:hover {
  border-color: var(--cyan-primary);
  color: var(--cyan-primary);
  background: rgba(0, 242, 254, 0.08);
  transform: translateY(-2px);
}

.btn-lg {
  padding: 15px 36px;
  font-size: 1.08rem;
}

.btn-block {
  width: 100%;
}

/* ==========================================================================
   英雄区域 (Hero Section)
   ========================================================================== */
.hero-section {
  padding-top: 150px;
  padding-bottom: 90px;
  text-align: center;
  position: relative;
}

.hero-badge-wrap {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(0, 242, 254, 0.08);
  border: 1px solid rgba(0, 242, 254, 0.28);
  padding: 6px 18px;
  border-radius: var(--radius-full);
  margin-bottom: 24px;
}

.badge-dot {
  width: 8px;
  height: 8px;
  background: var(--accent-emerald);
  border-radius: 50%;
  box-shadow: 0 0 10px var(--accent-emerald);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% { transform: scale(0.95); opacity: 0.8; }
  50% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(0.95); opacity: 0.8; }
}

.badge-text {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--cyan-light);
  letter-spacing: 0.5px;
}

.hero-title {
  font-size: 3.2rem;
  line-height: 1.2;
  font-weight: 800;
  margin-bottom: 24px;
  letter-spacing: -0.5px;
}

.text-gradient {
  background: var(--cyan-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.text-gradient-purple {
  background: var(--purple-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  max-width: 840px;
  margin-left: auto;
  margin-right: auto;
  font-size: 1.15rem;
  color: var(--text-muted);
  line-height: 1.8;
  margin-bottom: 38px;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 50px;
}

.hero-protocols {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 60px;
}

.protocol-tag {
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid rgba(56, 189, 248, 0.18);
  padding: 5px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

/* 核心信誉指标条 */
.hero-stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px 20px;
  box-shadow: var(--shadow-card);
}

.stat-item {
  text-align: center;
  position: relative;
}

.stat-item:not(:last-child)::after {
  content: '';
  position: absolute;
  right: 0;
  top: 15%;
  height: 70%;
  width: 1px;
  background: rgba(56, 189, 248, 0.15);
}

.stat-num {
  font-size: 2.2rem;
  font-weight: 800;
  color: #ffffff;
  line-height: 1.1;
  margin-bottom: 6px;
  font-family: var(--font-mono);
}

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

/* ==========================================================================
   通用区块头部规范 (Section Header)
   ========================================================================== */
.section-header {
  text-align: center;
  max-width: 820px;
  margin: 0 auto 50px auto;
}

.section-badge {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  color: var(--cyan-primary);
  text-transform: uppercase;
  margin-bottom: 12px;
  background: rgba(0, 242, 254, 0.08);
  border: 1px solid rgba(0, 242, 254, 0.2);
  padding: 4px 12px;
  border-radius: var(--radius-full);
}

.section-title {
  font-size: 2.3rem;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 16px;
}

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

/* ==========================================================================
   套餐定价专区 - 严格规范：所有价格同排排列 (Desktop 4-Col Row)
   ========================================================================== */
.pricing-section {
  padding: 80px 0 100px 0;
  position: relative;
}

/* 计费周期切换栏 */
.pricing-cycle-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-bottom: 38px;
  flex-wrap: wrap;
}

.cycle-btn {
  background: rgba(15, 23, 42, 0.7);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 10px 24px;
  border-radius: var(--radius-full);
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  backdrop-filter: blur(8px);
}

.cycle-btn:hover {
  color: #ffffff;
  border-color: var(--cyan-primary);
  background: rgba(0, 242, 254, 0.08);
}

.cycle-btn.active {
  background: var(--cyan-gradient);
  color: #030712;
  border-color: transparent;
  box-shadow: 0 4px 18px var(--cyan-glow);
  font-weight: 700;
}

.save-pill {
  background: #f43f5e;
  color: #ffffff;
  font-size: 0.72rem;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  font-weight: 800;
}

/* 核心：4 档方案严格同行同排展示 (Desktop 4-Col Same-Row Layout) */
.pricing-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
  align-items: stretch;
}

.price-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 30px 20px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  position: relative;
  transition: var(--transition);
  box-shadow: var(--shadow-card);
  height: 100%;
}

.price-card:hover {
  transform: translateY(-6px);
  border-color: var(--border-hover);
  box-shadow: var(--shadow-glow);
  background: var(--bg-card-hover);
}

/* 热门推荐卡片高亮样式 */
.price-card.featured {
  border-color: var(--cyan-primary);
  background: rgba(14, 28, 56, 0.9);
  box-shadow: 0 16px 48px -8px rgba(0, 242, 254, 0.35);
}

.featured-ribbon {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--cyan-gradient);
  color: #030712;
  font-size: 0.76rem;
  font-weight: 800;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  letter-spacing: 0.5px;
  box-shadow: 0 4px 14px var(--cyan-glow);
  white-space: nowrap;
}

.plan-top-info {
  margin-bottom: 22px;
}

.plan-tier-badge {
  font-size: 0.76rem;
  font-family: var(--font-mono);
  color: var(--cyan-light);
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 6px;
  display: block;
}

.plan-name {
  font-size: 1.4rem;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 8px;
}

.plan-summary {
  font-size: 0.88rem;
  color: var(--text-muted);
  min-height: 44px;
  line-height: 1.5;
  margin-bottom: 18px;
}

.price-amount-box {
  background: rgba(3, 7, 18, 0.65);
  border-radius: var(--radius-md);
  padding: 16px 14px;
  border: 1px solid rgba(56, 189, 248, 0.12);
  margin-bottom: 22px;
  text-align: center;
}

.price-main {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 3px;
  margin-bottom: 4px;
}

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

.price-number {
  font-size: 2.2rem;
  font-weight: 900;
  color: #ffffff;
  font-family: var(--font-mono);
  line-height: 1;
}

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

.price-equivalent {
  font-size: 0.8rem;
  color: var(--cyan-light);
  font-weight: 500;
}

.plan-features-list {
  list-style: none;
  margin-bottom: 28px;
  flex-grow: 1;
}

.plan-features-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.9rem;
  color: var(--text-main);
  margin-bottom: 12px;
  line-height: 1.5;
}

.plan-features-list li.dimmed {
  color: var(--text-dim);
}

.feature-icon-check {
  color: var(--accent-emerald);
  font-weight: bold;
  font-size: 1rem;
}

.feature-icon-cross {
  color: var(--text-dim);
  font-size: 0.95rem;
}

.plan-cta-wrap {
  margin-top: auto;
}

.price-footnote {
  text-align: center;
  font-size: 0.76rem;
  color: var(--text-dim);
  margin-top: 10px;
}

/* ==========================================================================
   核心技术与服务优势专区 (Features Section)
   ========================================================================== */
.features-section {
  padding: 80px 0;
  position: relative;
}

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

.feature-card {
  background: var(--bg-card);
  backdrop-filter: blur(14px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: var(--transition);
}

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

.feature-icon-box {
  width: 54px;
  height: 54px;
  border-radius: var(--radius-md);
  background: rgba(0, 242, 254, 0.1);
  border: 1px solid rgba(0, 242, 254, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 20px;
}

.feature-title {
  font-size: 1.22rem;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 12px;
}

.feature-desc {
  font-size: 0.92rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ==========================================================================
   全球节点网络分布 (Global Nodes Section)
   ========================================================================== */
.nodes-section {
  padding: 80px 0;
  position: relative;
}

.nodes-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.node-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 18px 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  transition: var(--transition);
}

.node-card:hover {
  border-color: var(--cyan-primary);
  background: rgba(14, 28, 56, 0.85);
  transform: translateY(-3px);
}

.node-flag {
  font-size: 1.8rem;
  line-height: 1;
}

.node-info {
  flex-grow: 1;
}

.node-name {
  font-size: 0.98rem;
  font-weight: 600;
  color: #ffffff;
  margin-bottom: 4px;
}

.node-meta {
  font-size: 0.78rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 8px;
}

.node-ping {
  color: var(--accent-emerald);
  font-family: var(--font-mono);
  font-weight: 600;
}

/* ==========================================================================
   文章专栏与知识库预览 (Articles Preview Section)
   ========================================================================== */
.articles-section {
  padding: 80px 0;
  position: relative;
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 40px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition);
  text-decoration: none;
  color: inherit;
}

.article-card:hover {
  border-color: var(--cyan-primary);
  transform: translateY(-5px);
  box-shadow: var(--shadow-sm);
  background: var(--bg-card-hover);
}

.article-tag {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--cyan-light);
  background: rgba(0, 242, 254, 0.1);
  padding: 3px 10px;
  border-radius: var(--radius-full);
  margin-bottom: 14px;
  width: fit-content;
  font-weight: 600;
}

.article-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: #ffffff;
  line-height: 1.45;
  margin-bottom: 12px;
  transition: var(--transition);
}

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

.article-card-snippet {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.65;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-dim);
  border-top: 1px solid rgba(56, 189, 248, 0.1);
  padding-top: 14px;
}

.article-read-more {
  color: var(--cyan-light);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* ==========================================================================
   真实用户好评专区 (Testimonials Section)
   ========================================================================== */
.testimonials-section {
  padding: 80px 0;
  position: relative;
}

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

.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition);
}

.testimonial-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
}

.testimonial-stars {
  color: var(--accent-gold);
  font-size: 1.1rem;
  margin-bottom: 14px;
}

.testimonial-quote {
  font-size: 0.94rem;
  color: #e2e8f0;
  line-height: 1.7;
  margin-bottom: 22px;
  flex-grow: 1;
}

.testimonial-author {
  display: flex;
  align-items: center;
  gap: 14px;
  border-top: 1px solid rgba(56, 189, 248, 0.1);
  padding-top: 14px;
}

.author-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--cyan-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  color: #030712;
  font-size: 1.1rem;
}

.author-info h4 {
  font-size: 0.96rem;
  color: #ffffff;
  margin-bottom: 2px;
}

.author-info p {
  font-size: 0.78rem;
  color: var(--text-dim);
}

/* ==========================================================================
   常见问题 FAQ 手风琴专区 (FAQ Section)
   ========================================================================== */
.faq-section {
  padding: 80px 0;
  position: relative;
}

.faq-list {
  max-width: 880px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

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

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

.faq-item.active {
  border-color: var(--cyan-primary);
  background: var(--bg-card-hover);
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: 22px 26px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  text-align: left;
  cursor: pointer;
  color: #ffffff;
  font-size: 1.05rem;
  font-weight: 600;
  font-family: inherit;
  transition: var(--transition);
}

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

.faq-icon {
  font-size: 1.3rem;
  color: var(--cyan-primary);
  transition: transform 0.28s ease;
  line-height: 1;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s cubic-bezier(0, 1, 0, 1);
}

.faq-answer-inner {
  padding: 0 26px 24px 26px;
  font-size: 0.94rem;
  color: var(--text-muted);
  line-height: 1.8;
  border-top: 1px dashed rgba(56, 189, 248, 0.12);
  margin-top: 4px;
  padding-top: 16px;
}

/* ==========================================================================
   推荐生态与外链资源 (External Links Section)
   ========================================================================== */
.external-links-section {
  padding: 60px 0 80px 0;
  position: relative;
}

.links-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}

.link-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: inherit;
  transition: var(--transition);
}

.link-card:hover {
  border-color: var(--cyan-primary);
  transform: translateY(-3px);
  background: var(--bg-card-hover);
}

.link-icon-title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
}

.link-icon {
  font-size: 1.3rem;
}

.link-title {
  font-size: 0.98rem;
  font-weight: 700;
  color: #ffffff;
}

.link-desc {
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ==========================================================================
   全站页脚 (Site Footer)
   ========================================================================== */
.site-footer {
  background: rgba(2, 6, 23, 0.96);
  border-top: 1px solid rgba(56, 189, 248, 0.15);
  padding: 70px 0 35px 0;
  position: relative;
  z-index: 10;
}

.footer-top-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 50px;
}

.footer-brand p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-top: 16px;
  max-width: 380px;
}

.footer-col h4 {
  font-size: 1rem;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 20px;
  position: relative;
  padding-bottom: 8px;
}

.footer-col h4::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 24px;
  height: 2px;
  background: var(--cyan-primary);
  border-radius: 2px;
}

.footer-col ul {
  list-style: none;
}

.footer-col ul li {
  margin-bottom: 10px;
}

.footer-col ul li a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.88rem;
  transition: var(--transition);
}

.footer-col ul li a:hover {
  color: var(--cyan-primary);
  padding-left: 4px;
}

.footer-bottom {
  border-top: 1px solid rgba(56, 189, 248, 0.1);
  padding-top: 25px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.84rem;
  color: var(--text-dim);
  flex-wrap: wrap;
  gap: 16px;
}

.footer-disclaimer {
  max-width: 780px;
  line-height: 1.6;
}

/* 返回顶部浮动按钮 */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--cyan-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 99;
  opacity: 0;
  pointer-events: none;
  transition: var(--transition);
  font-size: 1.2rem;
  box-shadow: var(--shadow-sm);
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.back-to-top:hover {
  background: var(--cyan-primary);
  color: #030712;
  transform: translateY(-3px);
  box-shadow: 0 6px 20px var(--cyan-glow);
}

/* ==========================================================================
   响应式断点适配 (Responsive Breakpoints)
   ========================================================================== */
@media (max-width: 1200px) {
  .pricing-row {
    grid-template-columns: repeat(4, minmax(0, 1fr)) !important;
    gap: 12px;
  }
  .price-card {
    padding: 24px 14px;
  }
  .price-number {
    font-size: 1.85rem;
  }
  .hero-title {
    font-size: 2.7rem;
  }
  .nodes-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 992px) {
  .header-inner {
    height: 68px;
  }
  .nav-menu {
    position: fixed;
    top: 68px;
    left: 0;
    width: 100%;
    background: rgba(3, 7, 18, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 30px;
    gap: 20px;
    border-bottom: 1px solid var(--border-color);
    transform: translateY(-120%);
    transition: transform 0.3s ease;
    z-index: 99;
  }
  .nav-menu.active {
    transform: translateY(0);
  }
  .mobile-menu-toggle {
    display: block;
  }
  .hero-title {
    font-size: 2.2rem;
  }
  .hero-stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
  }
  .stat-item:nth-child(2)::after {
    display: none;
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  /* 严格规范：所有价格卡片在桌面/平板端坚决保持同排展示 (4-Col Row) */
  .pricing-row {
    grid-template-columns: repeat(4, minmax(0, 1fr)) !important;
    gap: 10px;
  }
  .price-card {
    padding: 20px 10px;
  }
  .price-number {
    font-size: 1.55rem;
  }
  .plan-name {
    font-size: 1.15rem;
  }
  .plan-summary {
    font-size: 0.8rem;
    min-height: 40px;
  }
  .plan-features-list li {
    font-size: 0.82rem;
    margin-bottom: 8px;
  }
  .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .testimonials-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .links-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-top-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  /* 移动端/窄屏：横向滑动流体容器，确保全套价格 100% 同一行水平排列，支持平滑轻扫 */
  .pricing-row {
    display: flex !important;
    flex-wrap: nowrap !important;
    overflow-x: auto !important;
    scroll-snap-type: x mandatory;
    gap: 14px !important;
    padding-bottom: 16px;
    -webkit-overflow-scrolling: touch;
  }
  .price-card {
    min-width: 260px !important;
    flex: 0 0 260px !important;
    scroll-snap-align: start;
    padding: 24px 18px;
  }
  .hero-title {
    font-size: 1.85rem;
  }
  .hero-desc {
    font-size: 0.98rem;
  }
  .hero-stats-grid {
    grid-template-columns: 1fr;
  }
  .stat-item::after {
    display: none !important;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .nodes-grid {
    grid-template-columns: 1fr;
  }
  .articles-grid {
    grid-template-columns: 1fr;
  }
  .testimonials-grid {
    grid-template-columns: 1fr;
  }
  .links-grid {
    grid-template-columns: 1fr;
  }
  .footer-top-grid {
    grid-template-columns: 1fr;
  }
  .hero-cta-group {
    flex-direction: column;
    width: 100%;
  }
  .hero-cta-group .btn {
    width: 100%;
  }
}