/* ==========================================================================
   ImmTelecom (immtelecom.site) - 官方极速落地页纯原生样式表
   规范：纯原生 CSS · 零外部重型框架 · 秒开级加载性能 · 全端自适应响应式
   ========================================================================== */

:root {
  --bg-main: #060913;
  --bg-card: rgba(14, 21, 41, 0.78);
  --bg-card-hover: rgba(20, 31, 61, 0.88);
  --bg-card-featured: rgba(16, 28, 58, 0.92);
  --border-subtle: rgba(56, 189, 248, 0.12);
  --border-glow: rgba(56, 189, 248, 0.35);
  --border-featured: rgba(0, 242, 254, 0.45);
  
  --primary: #ffd000;
  --primary-hover: #fffb91;
  --primary-glow: rgba(255, 208, 0, 0.45);
  
  --ice-yellow: #fffb91;
  --ice-yellow-core: #ffd000;
  --ice-yellow-glow: rgba(255, 208, 0, 0.45);
  
  --accent-cyan: #38bdf8;
  --accent-purple: #8b5cf6;
  --accent-green: #10b981;
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;
  
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-sub: #cbd5e1;
  --text-dark: #0f172a;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 20px 45px -15px rgba(0, 242, 254, 0.15);
  --shadow-card: 0 12px 32px rgba(0, 0, 0, 0.36);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --transition: all 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
  position: relative;
  overflow-x: hidden;
  background-color: var(--bg-main);
  min-height: 100vh;
}

/* 动态背景画布 */
#bg-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 0;
  opacity: 1;
}

/* 页面包裹层 */
.page-wrapper {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

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

/* 通用排版 */
a {
  color: inherit;
  text-decoration: none;
  transition: var(--transition);
}

ul, ol {
  list-style: none;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

.text-gradient {
  background: linear-gradient(135deg, #ffffff 0%, #fffb91 32%, #ffd000 68%, #f59e0b 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.text-gradient-purple {
  background: linear-gradient(135deg, #a78bfa 0%, #38bdf8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* 徽章与标签 */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.badge-cyan {
  background: rgba(0, 242, 254, 0.1);
  color: #00f2fe;
  border: 1px solid rgba(0, 242, 254, 0.3);
}

.badge-purple {
  background: rgba(139, 92, 246, 0.12);
  color: #c084fc;
  border: 1px solid rgba(139, 92, 246, 0.3);
}

.badge-green {
  background: rgba(16, 185, 129, 0.12);
  color: #34d399;
  border: 1px solid rgba(16, 185, 129, 0.3);
}

/* 按钮系统 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
  white-space: nowrap;
  user-select: none;
  border: 1px solid transparent;
}

.btn-primary {
  background: linear-gradient(135deg, #fffb91 0%, #ffd000 55%, #f59e0b 100%);
  color: #0b1120;
  font-weight: 700;
  box-shadow: 0 0 25px rgba(255, 208, 0, 0.45);
  border: 1px solid rgba(255, 255, 255, 0.35);
}

.btn-primary:hover {
  background: linear-gradient(135deg, #ffffff 0%, #fffb91 50%, #ffd000 100%);
  box-shadow: 0 0 35px rgba(255, 208, 0, 0.75);
  transform: translateY(-2px);
  color: #000000;
}

.btn-outline {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-main);
  border-color: var(--border-glow);
  backdrop-filter: blur(8px);
}

.btn-outline:hover {
  background: rgba(56, 189, 248, 0.12);
  border-color: #38bdf8;
  color: #00f2fe;
  transform: translateY(-2px);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 0.88rem;
}

.btn-md {
  padding: 12px 24px;
  font-size: 0.98rem;
}

.btn-lg {
  padding: 16px 36px;
  font-size: 1.1rem;
  font-weight: 700;
  border-radius: 16px;
}

.btn-block {
  width: 100%;
}

/* ==========================================================================
   1. 顶部导航栏 (Header)
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  background: rgba(6, 9, 19, 0.82);
  border-bottom: 1px solid var(--border-subtle);
  transition: var(--transition);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 74px;
}

/* 左侧 Logo 规范：严格包含官方 Logo */
.site-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.site-logo img {
  height: 48px;
  width: auto;
  object-fit: contain;
  transition: var(--transition);
}

.site-logo:hover img {
  filter: drop-shadow(0 0 10px rgba(0, 242, 254, 0.45));
}

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

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-muted);
  position: relative;
  padding: 6px 0;
}

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

.nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background: linear-gradient(90deg, #00f2fe, #38bdf8);
  transition: var(--transition);
}

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

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

.mobile-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border-subtle);
  color: var(--text-main);
  padding: 8px;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

/* ==========================================================================
   2. 首屏 Hero 区域
   ========================================================================== */
.hero-section {
  position: relative;
  padding: 80px 0 60px;
  text-align: center;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: rgba(14, 21, 41, 0.85);
  border: 1px solid var(--border-glow);
  padding: 8px 20px;
  border-radius: var(--radius-full);
  font-size: 0.88rem;
  color: var(--accent-cyan);
  margin-bottom: 24px;
  box-shadow: 0 0 25px rgba(0, 242, 254, 0.12);
}

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

.pulse-dot::after {
  content: "";
  position: absolute;
  top: -4px;
  left: -4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 2px solid var(--accent-green);
  animation: pulse-ring 1.8s infinite;
}

@keyframes pulse-ring {
  0% { transform: scale(0.6); opacity: 1; }
  100% { transform: scale(1.6); opacity: 0; }
}

.hero-title {
  font-weight: 900;
  line-height: 1.3;
  letter-spacing: -0.01em;
  margin-bottom: 22px;
}

.hero-title-main {
  display: block;
  font-size: clamp(2.2rem, 3.8vw, 3.4rem);
  font-weight: 900;
  line-height: 1.22;
  margin-bottom: 12px;
}

.hero-title-sub {
  display: inline-block;
  font-size: clamp(1.35rem, 2.25vw, 2.1rem);
  font-weight: 800;
  letter-spacing: 0.02em;
  white-space: nowrap;
  line-height: 1.35;
}

.hero-desc {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--text-sub);
  max-width: 840px;
  margin: 0 auto 36px;
  line-height: 1.7;
}

.hero-cta-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin-bottom: 50px;
  flex-wrap: wrap;
}

/* 信任统计指标 */
.hero-stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  background: rgba(14, 21, 41, 0.65);
  border: 1px solid var(--border-subtle);
  backdrop-filter: blur(14px);
  border-radius: var(--radius-lg);
  padding: 24px 30px;
  margin-top: 20px;
}

.stat-item {
  text-align: center;
  border-right: 1px solid rgba(255, 255, 255, 0.08);
}

.stat-item:last-child {
  border-right: none;
}

.stat-num {
  font-size: 2.1rem;
  font-weight: 800;
  color: #00f2fe;
  font-family: var(--font-mono);
  line-height: 1.2;
}

.stat-label {
  font-size: 0.86rem;
  color: var(--text-muted);
  margin-top: 4px;
}

/* ==========================================================================
   3. 定价区域 (Pricing) - 核心规范：所有价格同排排列
   ========================================================================== */
.pricing-section {
  padding: 90px 0;
  position: relative;
}

.section-header {
  text-align: center;
  max-width: 800px;
  margin: 0 auto 40px;
}

.section-tag {
  display: inline-block;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: #00f2fe;
  text-transform: uppercase;
  margin-bottom: 10px;
}

.section-title {
  font-size: clamp(2rem, 3.6vw, 2.7rem);
  font-weight: 800;
  margin-bottom: 14px;
  letter-spacing: -0.01em;
}

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

/* 计费周期切换控制器 */
.pricing-cycle-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: rgba(14, 21, 41, 0.8);
  border: 1px solid var(--border-glow);
  padding: 6px;
  border-radius: var(--radius-full);
  max-width: 580px;
  margin: 0 auto 46px;
}

.cycle-btn {
  flex: 1;
  padding: 10px 18px;
  border-radius: var(--radius-full);
  font-size: 0.92rem;
  font-weight: 600;
  border: none;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.cycle-btn:hover {
  color: var(--text-main);
}

.cycle-btn.active {
  background: linear-gradient(135deg, rgba(0, 242, 254, 0.22) 0%, rgba(56, 189, 248, 0.3) 100%);
  color: #00f2fe;
  box-shadow: 0 0 15px rgba(0, 242, 254, 0.2);
  border: 1px solid rgba(0, 242, 254, 0.4);
}

.save-pill {
  font-size: 0.72rem;
  padding: 2px 8px;
  background: var(--accent-rose);
  color: #fff;
  border-radius: var(--radius-full);
  font-weight: 700;
}

/* 4 大套餐严格同排排列 (Desktop 4-Columns Grid - 严格同行无折行) */
.pricing-grid-same-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  align-items: stretch;
}

.price-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 32px 24px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  transition: var(--transition);
  box-shadow: var(--shadow-card);
}

.price-card:hover {
  transform: translateY(-8px);
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  box-shadow: 0 18px 40px rgba(0, 242, 254, 0.16);
}

/* 热门推荐卡片视觉强化 */
.price-card.featured {
  background: var(--bg-card-featured);
  border: 1.5px solid var(--border-featured);
  box-shadow: 0 0 35px rgba(0, 242, 254, 0.2);
  transform: scale(1.02);
}

.price-card.featured:hover {
  transform: scale(1.02) translateY(-8px);
  border-color: #00f2fe;
  box-shadow: 0 0 45px rgba(0, 242, 254, 0.35);
}

.featured-ribbon {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #fffb91 0%, #ffd000 60%, #f59e0b 100%);
  color: #0b1120;
  padding: 4px 18px;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  white-space: nowrap;
  box-shadow: 0 4px 14px rgba(255, 208, 0, 0.45);
}

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

.plan-tier-badge {
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--accent-cyan);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 8px;
  display: block;
}

.plan-name {
  font-size: 1.45rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 8px;
}

.plan-summary {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.55;
  min-height: 42px;
}

/* 价格数值展示盒 */
.price-amount-box {
  background: rgba(6, 9, 19, 0.55);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-md);
  padding: 16px 14px;
  margin: 18px 0;
  text-align: center;
}

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

.price-currency {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--primary);
}

.price-number {
  font-size: 2.7rem;
  font-weight: 900;
  color: #ffffff;
  line-height: 1;
  font-family: var(--font-mono);
}

.price-cycle {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-left: 4px;
}

.price-equivalent {
  font-size: 0.82rem;
  color: var(--accent-cyan);
  margin-top: 6px;
  font-weight: 500;
}

/* 套餐特性清单 */
.plan-features-list {
  margin-bottom: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.plan-features-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.88rem;
  color: var(--text-sub);
  line-height: 1.48;
}

.feature-check {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: rgba(16, 185, 129, 0.15);
  color: #10b981;
  font-size: 0.72rem;
  font-weight: 900;
  flex-shrink: 0;
  margin-top: 2px;
}

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

.price-footnote {
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 10px;
}

/* ==========================================================================
   4. 技术特性与网络架构 (Features)
   ========================================================================== */
.features-section {
  padding: 80px 0;
}

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

.feature-box {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: var(--transition);
  backdrop-filter: blur(12px);
}

.feature-box:hover {
  border-color: var(--border-glow);
  transform: translateY(-5px);
  background: var(--bg-card-hover);
  box-shadow: 0 10px 30px rgba(0, 242, 254, 0.1);
}

.feature-icon-wrap {
  width: 54px;
  height: 54px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, rgba(0, 242, 254, 0.15) 0%, rgba(59, 130, 246, 0.2) 100%);
  border: 1px solid var(--border-glow);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
  color: var(--primary);
}

.feature-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-main);
}

.feature-desc {
  font-size: 0.92rem;
  color: var(--text-muted);
  line-height: 1.65;
}

/* ==========================================================================
   5. 全球骨干节点分布 (Nodes)
   ========================================================================== */
.nodes-section {
  padding: 80px 0;
}

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

.node-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 20px;
  display: flex;
  align-items: center;
  gap: 14px;
  transition: var(--transition);
}

.node-card:hover {
  border-color: var(--border-glow);
  background: var(--bg-card-hover);
  transform: translateY(-3px);
}

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

.node-info {
  flex: 1;
}

.node-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
}

.node-detail {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.node-ping {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent-green);
  font-family: var(--font-mono);
  background: rgba(16, 185, 129, 0.12);
  padding: 4px 8px;
  border-radius: var(--radius-full);
}

/* ==========================================================================
   6. 客户端支持与一键导入
   ========================================================================== */
.clients-section {
  padding: 80px 0;
}

.clients-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 18px;
}

.client-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 24px 18px;
  text-align: center;
  transition: var(--transition);
}

.client-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-5px);
  background: var(--bg-card-hover);
}

.client-icon {
  font-size: 2.2rem;
  margin-bottom: 12px;
}

.client-name {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.client-apps {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* ==========================================================================
   7. 知识专栏与文章展示 (Articles Section on Index)
   ========================================================================== */
.articles-section {
  padding: 80px 0;
}

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

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

.article-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-6px);
  background: var(--bg-card-hover);
  box-shadow: 0 12px 35px rgba(0, 242, 254, 0.12);
}

.article-tag {
  font-size: 0.76rem;
  font-weight: 700;
  color: var(--accent-cyan);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 10px;
  display: inline-block;
}

.article-title {
  font-size: 1.18rem;
  font-weight: 700;
  line-height: 1.45;
  margin-bottom: 12px;
  color: var(--text-main);
}

.article-excerpt {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 20px;
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding-top: 14px;
  font-size: 0.82rem;
  color: var(--text-muted);
}

.article-readmore {
  color: var(--primary);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.article-readmore:hover {
  color: #fff;
  transform: translateX(3px);
}

/* ==========================================================================
   8. 用户评价 (Testimonials) - 规范要求
   ========================================================================== */
.testimonials-section {
  padding: 80px 0;
}

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

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

.testimonial-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-5px);
  background: var(--bg-card-hover);
}

.test-stars {
  color: #fbbf24;
  font-size: 1rem;
  margin-bottom: 14px;
  letter-spacing: 2px;
}

.test-quote {
  font-size: 0.94rem;
  color: var(--text-sub);
  line-height: 1.68;
  margin-bottom: 22px;
  font-style: italic;
}

.test-user {
  display: flex;
  align-items: center;
  gap: 12px;
}

.test-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: linear-gradient(135deg, #00f2fe 0%, #a78bfa 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: #050b1a;
  font-size: 1.1rem;
}

.test-name {
  font-size: 0.96rem;
  font-weight: 700;
  color: var(--text-main);
}

.test-role {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* ==========================================================================
   9. 常见问题 FAQ (Accordion) - 规范要求
   ========================================================================== */
.faq-section {
  padding: 80px 0 100px;
}

.faq-container {
  max-width: 860px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  margin-bottom: 14px;
  overflow: hidden;
  transition: var(--transition);
}

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

.faq-item.active {
  border-color: #00f2fe;
  background: var(--bg-card-hover);
}

.faq-question {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 20px 24px;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  transition: var(--transition);
}

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

.faq-icon {
  font-size: 1.4rem;
  line-height: 1;
  transition: transform 0.3s ease;
  color: var(--accent-cyan);
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
  color: #f43f5e;
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease-out, padding 0.3s ease;
  padding: 0 24px;
}

.faq-item.active .faq-answer {
  max-height: 400px;
  padding: 0 24px 22px;
}

.faq-answer p {
  font-size: 0.94rem;
  color: var(--text-sub);
  line-height: 1.7;
}

/* ==========================================================================
   10. 底部呼召横幅 (CTA Banner)
   ========================================================================== */
.cta-banner-section {
  padding: 40px 0 80px;
}

.cta-banner {
  background: linear-gradient(135deg, rgba(14, 26, 56, 0.95) 0%, rgba(20, 36, 76, 0.95) 100%);
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-lg);
  padding: 50px 40px;
  text-align: center;
  box-shadow: 0 0 50px rgba(0, 242, 254, 0.15);
  position: relative;
  overflow: hidden;
}

.cta-banner::before {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(0, 242, 254, 0.08) 0%, transparent 60%);
  pointer-events: none;
}

.cta-banner-title {
  font-size: clamp(1.8rem, 3.2vw, 2.5rem);
  font-weight: 800;
  margin-bottom: 16px;
}

.cta-banner-desc {
  font-size: 1.05rem;
  color: var(--text-sub);
  max-width: 680px;
  margin: 0 auto 30px;
}

/* ==========================================================================
   11. 权威外链专区 (External Links Shelf) - 规范要求
   ========================================================================== */
.ext-links-section {
  padding: 50px 0 30px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.ext-links-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 18px;
  text-align: center;
}

.ext-links-flex {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}

.ext-link-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(14, 21, 41, 0.6);
  border: 1px solid var(--border-subtle);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  font-size: 0.82rem;
  color: var(--text-muted);
  transition: var(--transition);
}

.ext-link-pill:hover {
  border-color: var(--accent-cyan);
  color: #fff;
  background: rgba(56, 189, 248, 0.12);
  transform: translateY(-2px);
}

/* ==========================================================================
   12. 网站页脚 (Footer)
   ========================================================================== */
.site-footer {
  background: rgba(4, 7, 15, 0.95);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding: 60px 0 30px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

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

.footer-brand p {
  margin-top: 14px;
  line-height: 1.65;
  color: var(--text-sub);
  font-size: 0.88rem;
}

.footer-col-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 18px;
}

.footer-links-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links-list a:hover {
  color: var(--primary);
  transform: translateX(3px);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding-top: 26px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 0.82rem;
}

/* ==========================================================================
   13. 响应式适配媒体查询 (Media Queries)
   ========================================================================== */
@media (max-width: 1200px) {
  .pricing-grid-same-row {
    gap: 14px;
  }
  .price-card {
    padding: 24px 18px 22px;
  }
  .price-number {
    font-size: 2.3rem;
  }
}

@media (max-width: 1024px) {
  /* 平板端横向滚动或 2x2 优雅适配 */
  .pricing-grid-same-row {
    grid-template-columns: repeat(2, 1fr);
    gap: 18px;
  }
  .hero-stats-row {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }
  .stat-item {
    border-right: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    padding-bottom: 12px;
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .nodes-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .clients-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .testimonials-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 30px;
  }
}

@media (max-width: 768px) {
  .hero-title-sub {
    white-space: normal;
    font-size: 1.25rem;
  }
  .nav-menu {
    position: fixed;
    top: 74px;
    left: 0;
    width: 100%;
    background: rgba(6, 9, 19, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 24px 0;
    gap: 18px;
    border-bottom: 1px solid var(--border-subtle);
    display: none;
  }
  .nav-menu.open {
    display: flex;
  }
  .mobile-toggle {
    display: block;
  }
  .header-actions .btn-outline {
    display: none;
  }
  .pricing-grid-same-row {
    grid-template-columns: 1fr;
    max-width: 440px;
    margin: 0 auto;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .clients-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .articles-grid {
    grid-template-columns: 1fr;
  }
  .testimonials-grid {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
}

/* ==========================================================================
   14. 投喂企鹅吃鱼互动浮窗组件 (Feed Penguin Interactive Widget)
   ========================================================================== */
.feed-penguin-widget {
  position: fixed;
  bottom: 28px;
  left: 28px;
  z-index: 99;
}

.feed-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 11px 20px;
  background: rgba(14, 21, 41, 0.94);
  border: 1.5px solid #ffd000;
  border-radius: var(--radius-full);
  color: #fff;
  font-family: var(--font-sans);
  font-size: 0.94rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 6px 24px rgba(255, 208, 0, 0.38), 0 2px 10px rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  transition: transform 0.22s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.22s ease, background 0.22s ease;
  user-select: none;
}

.feed-btn:hover {
  background: rgba(22, 34, 68, 0.98);
  box-shadow: 0 8px 32px rgba(255, 208, 0, 0.65), 0 3px 12px rgba(0, 0, 0, 0.6);
  transform: translateY(-3px) scale(1.05);
  border-color: #ffffff;
}

.feed-btn:active {
  transform: translateY(1px) scale(0.96);
}

.feed-btn-icon {
  font-size: 1.4rem;
  line-height: 1;
  display: inline-block;
  animation: fish-wiggle 1.5s ease-in-out infinite;
}

@keyframes fish-wiggle {
  0%, 100% { transform: rotate(0deg) scale(1); }
  25% { transform: rotate(-14deg) scale(1.15); }
  75% { transform: rotate(14deg) scale(1.15); }
}

.feed-btn-text {
  color: #f8fafc;
  letter-spacing: 0.02em;
}

.feed-btn-badge {
  font-size: 0.74rem;
  padding: 3px 9px;
  background: linear-gradient(135deg, #fffb91 0%, #ffd000 100%);
  color: #0b1120;
  border-radius: var(--radius-full);
  font-weight: 800;
}

@media (max-width: 768px) {
  .feed-penguin-widget {
    bottom: 18px;
    left: 16px;
  }
  .feed-btn {
    padding: 8px 14px;
    font-size: 0.84rem;
  }
  .feed-btn-badge {
    display: none;
  }
}