/* ==========================================================================
   SparkCloud 花火云网 (sparkcloud.mom) - 全站原生极速核心样式表
   零重型框架依赖 | 极致秒开体验 | 现代高质感暗黑花火美学
   ========================================================================== */

/* --- 1. CSS 变量与设计系统 --- */
:root {
  --bg-main: #070a14;
  --bg-card: rgba(15, 23, 42, 0.72);
  --bg-card-hover: rgba(22, 34, 62, 0.88);
  --bg-surface: #0e1526;
  --bg-nav: rgba(7, 10, 20, 0.85);

  /* 花火色彩：暖橙、耀金、火玫瑰与极光青 */
  --spark-primary: #ff6b35;
  --spark-secondary: #f59e0b;
  --spark-accent: #ff3366;
  --spark-cyan: #00f2fe;
  --spark-glow: rgba(255, 107, 53, 0.35);

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --text-spark: #fb923c;

  --border-light: rgba(255, 255, 255, 0.08);
  --border-spark: rgba(255, 107, 53, 0.3);
  --border-focus: rgba(0, 242, 254, 0.45);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.25);
  --shadow-card: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --shadow-spark: 0 8px 28px rgba(255, 107, 53, 0.32);
  --shadow-cyan: 0 8px 28px rgba(0, 242, 254, 0.25);

  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --container-width: 1240px;
}

/* --- 2. 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-primary);
  line-height: 1.65;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  position: relative;
  min-height: 100vh;
  overflow-x: hidden;
  background-color: transparent;
}

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

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

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

/* --- 3. 动态背景层 (HTML5 Canvas 各种绚丽烟花 + CSS 空间背景) --- */
#dynamic-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: 1; /* 正向 z-index 确保在背景之上、在卡片内容之下 */
  pointer-events: none;
  transform: translateZ(0);
  will-change: transform;
}

.bg-nebula-ambient {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  background: 
    radial-gradient(circle at 18% 22%, rgba(255, 107, 53, 0.12) 0%, transparent 45%),
    radial-gradient(circle at 82% 35%, rgba(0, 242, 254, 0.09) 0%, transparent 50%),
    radial-gradient(circle at 50% 80%, rgba(255, 51, 102, 0.08) 0%, transparent 60%);
  animation: nebulaBreathe 18s ease-in-out infinite alternate;
}

main {
  position: relative;
  z-index: 2;
}

@keyframes nebulaBreathe {
  0% { transform: scale(1) translateY(0); opacity: 0.8; }
  50% { transform: scale(1.04) translateY(-10px); opacity: 1; }
  100% { transform: scale(1) translateY(5px); opacity: 0.85; }
}

/* --- 4. 容器与通用排版 --- */
.container {
  width: 100%;
  max-width: var(--container-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.section-spacing {
  padding-top: 96px;
  padding-bottom: 96px;
}

.section-header {
  text-align: center;
  max-width: 780px;
  margin: 0 auto 56px;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: rgba(255, 107, 53, 0.12);
  border: 1px solid var(--border-spark);
  color: var(--spark-secondary);
  font-size: 0.86rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  margin-bottom: 16px;
  text-transform: uppercase;
}

.section-tag .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--spark-primary);
  box-shadow: 0 0 10px var(--spark-primary);
  animation: pulseDot 2s infinite;
}

@keyframes pulseDot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(0.8); }
}

.section-title {
  font-size: 2.35rem;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 18px;
  color: #ffffff;
  letter-spacing: -0.5px;
}

.section-title .text-gradient {
  background: linear-gradient(135deg, #ff6b35 0%, #ffc107 50%, #00f2fe 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

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

/* --- 5. 导航栏 (Header / Navbar) --- */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  background: var(--bg-nav);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-light);
  transition: all var(--transition-smooth);
}

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

.brand-logo-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-logo-wrap img {
  height: 44px;
  width: auto;
  transition: transform var(--transition-fast);
}

.brand-logo-wrap:hover img {
  transform: scale(1.02);
}

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

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding: 8px 0;
  transition: color var(--transition-fast);
}

.nav-link:hover, .nav-link.active {
  color: #ffffff;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--spark-primary), var(--spark-secondary));
  transition: width var(--transition-smooth);
}

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

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

/* CTA 按钮基础规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 11px 24px;
  border-radius: var(--radius-full);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.3px;
  transition: all var(--transition-smooth);
  white-space: nowrap;
}

.btn-spark {
  background: linear-gradient(135deg, #ff6b35 0%, #ff3366 100%);
  color: #ffffff;
  box-shadow: var(--shadow-spark);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn-spark:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(255, 107, 53, 0.45);
  background: linear-gradient(135deg, #ff7e4d 0%, #ff477e 100%);
  color: #ffffff;
}

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

.btn-outline {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-primary);
  border: 1px solid var(--border-light);
  backdrop-filter: blur(8px);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.25);
  color: #ffffff;
  transform: translateY(-2px);
}

.btn-lg {
  padding: 15px 34px;
  font-size: 1.08rem;
  border-radius: var(--radius-full);
}

.mobile-menu-btn {
  display: none;
  font-size: 1.6rem;
  color: var(--text-primary);
  padding: 6px;
}

/* --- 6. 英雄区 (Hero Section) --- */
.hero-section {
  position: relative;
  padding-top: 80px;
  padding-bottom: 90px;
  text-align: center;
  overflow: hidden;
}

.hero-notice-pill {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 7px 20px;
  background: rgba(255, 107, 53, 0.1);
  border: 1px solid var(--border-spark);
  border-radius: var(--radius-full);
  margin-bottom: 28px;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.hero-notice-pill .pill-tag {
  background: var(--spark-primary);
  color: #ffffff;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  text-transform: uppercase;
}

.hero-title {
  font-size: clamp(2rem, 3.15vw, 3.05rem);
  font-weight: 900;
  line-height: 1.28;
  letter-spacing: -0.6px;
  margin-bottom: 24px;
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
}

.hero-title-line1 {
  display: block;
  margin-bottom: 8px;
}

.hero-title-line2 {
  display: block;
}

.title-chunk {
  display: inline-block;
  white-space: nowrap;
}

.title-sep {
  display: inline-block;
  margin: 0 4px;
  opacity: 0.65;
}

.hero-subtitle {
  font-size: 1.22rem;
  color: var(--text-secondary);
  max-width: 820px;
  margin: 0 auto 40px;
  line-height: 1.75;
}

.hero-ctas {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  margin-bottom: 56px;
  flex-wrap: wrap;
}

.hero-trust-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 40px;
  flex-wrap: wrap;
  padding: 22px 32px;
  background: rgba(15, 23, 42, 0.5);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  max-width: 1040px;
  margin: 0 auto;
  backdrop-filter: blur(10px);
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 12px;
  text-align: left;
}

.trust-icon {
  font-size: 1.6rem;
  color: var(--spark-secondary);
}

.trust-item strong {
  display: block;
  font-size: 1.25rem;
  font-weight: 800;
  color: #ffffff;
  line-height: 1.2;
}

.trust-item span {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* --- 7. 核心架构与特性 (Features Section) --- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 32px 26px;
  transition: all var(--transition-smooth);
  backdrop-filter: blur(12px);
  display: flex;
  flex-direction: column;
}

.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-spark);
  transform: translateY(-5px);
  box-shadow: var(--shadow-card);
}

.feature-icon-box {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  background: linear-gradient(135deg, rgba(255, 107, 53, 0.15) 0%, rgba(245, 158, 11, 0.15) 100%);
  border: 1px solid var(--border-spark);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.7rem;
  margin-bottom: 22px;
  color: var(--spark-primary);
}

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

.feature-desc {
  font-size: 0.94rem;
  color: var(--text-muted);
  line-height: 1.68;
}

/* --- 8. 实时全球专线网络节点展示 (Global Nodes) --- */
.nodes-overview-box {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px;
  backdrop-filter: blur(14px);
}

.node-chips-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-top: 28px;
}

.node-chip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 18px;
  background: rgba(14, 21, 38, 0.85);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.node-chip:hover {
  border-color: var(--spark-cyan);
  background: rgba(18, 30, 56, 0.95);
  transform: translateY(-2px);
}

.node-flag-name {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 0.95rem;
}

.node-flag {
  font-size: 1.3rem;
}

.node-status {
  text-align: right;
}

.node-ping {
  font-size: 0.82rem;
  font-weight: 700;
  color: #10b981;
  font-family: var(--font-mono);
}

.node-line {
  font-size: 0.72rem;
  color: var(--text-muted);
  display: block;
}

/* --- 9. 核心套餐价格区域 (Pricing Section - 必须全部同排展示) --- */
.pricing-section {
  position: relative;
  background: linear-gradient(180deg, rgba(7, 10, 20, 0) 0%, rgba(14, 21, 38, 0.45) 50%, rgba(7, 10, 20, 0) 100%);
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr); /* 严格同排展示 4 档套餐 */
  gap: 20px;
  align-items: stretch;
}

.pricing-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px 26px 30px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-smooth);
  backdrop-filter: blur(14px);
}

.pricing-card:hover {
  transform: translateY(-8px);
  border-color: rgba(255, 107, 53, 0.5);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.6), 0 0 25px rgba(255, 107, 53, 0.18);
  background: var(--bg-card-hover);
}

/* 热门力荐高亮样式 */
.pricing-card.popular {
  border-color: var(--spark-primary);
  box-shadow: 0 12px 36px rgba(255, 107, 53, 0.28);
  background: linear-gradient(180deg, rgba(30, 41, 68, 0.9) 0%, rgba(17, 24, 43, 0.85) 100%);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(90deg, #ff6b35, #ff3366);
  color: #ffffff;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  letter-spacing: 0.8px;
  box-shadow: 0 4px 14px rgba(255, 51, 102, 0.4);
  white-space: nowrap;
}

.pricing-header {
  margin-bottom: 24px;
  text-align: left;
}

.plan-name {
  font-size: 1.35rem;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 6px;
}

.plan-desc {
  font-size: 0.86rem;
  color: var(--text-muted);
  min-height: 40px;
  line-height: 1.5;
}

.price-wrap {
  display: flex;
  align-items: baseline;
  gap: 4px;
  margin: 18px 0 14px;
}

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

.price-amount {
  font-size: 2.6rem;
  font-weight: 900;
  color: #ffffff;
  line-height: 1;
  font-family: var(--font-sans);
}

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

.plan-specs-box {
  background: rgba(10, 15, 29, 0.65);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  margin-bottom: 22px;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.spec-row {
  display: flex;
  justify-content: space-between;
  font-size: 0.88rem;
  padding: 4px 0;
}

.spec-label {
  color: var(--text-muted);
}

.spec-val {
  color: #ffffff;
  font-weight: 600;
}

.spec-val.highlight {
  color: var(--spark-secondary);
}

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

.plan-features-list li {
  font-size: 0.88rem;
  color: var(--text-secondary);
  padding: 7px 0;
  display: flex;
  align-items: flex-start;
  gap: 9px;
  line-height: 1.45;
}

.plan-features-list li svg,
.plan-features-list li .check-icon {
  color: #10b981;
  font-size: 1rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.pricing-btn-wrap {
  margin-top: auto;
}

.pricing-btn-wrap .btn {
  width: 100%;
}

.guarantee-note {
  text-align: center;
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 10px;
}

/* --- 10. 文章专栏聚合板块 (Articles Showcase) --- */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 26px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-smooth);
  backdrop-filter: blur(12px);
}

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

.article-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--spark-secondary);
  background: rgba(245, 158, 11, 0.12);
  border: 1px solid rgba(245, 158, 11, 0.25);
  padding: 3px 10px;
  border-radius: var(--radius-full);
  margin-bottom: 14px;
}

.article-title-link {
  font-size: 1.15rem;
  font-weight: 700;
  color: #ffffff;
  line-height: 1.45;
  margin-bottom: 12px;
  display: block;
}

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

.article-snippet {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 20px;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.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-read-more {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--spark-primary);
  font-weight: 600;
  font-size: 0.88rem;
}

.article-read-more:hover {
  color: var(--spark-secondary);
  gap: 9px;
}

/* --- 11. 客户端与简易使用步骤 (Clients & Setup) --- */
.clients-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 18px;
  margin-bottom: 56px;
}

.client-item {
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 24px 18px;
  text-align: center;
  transition: all var(--transition-fast);
}

.client-item:hover {
  border-color: var(--spark-cyan);
  background: rgba(22, 34, 62, 0.8);
  transform: translateY(-4px);
}

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

.client-name {
  font-size: 1.05rem;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 4px;
}

.client-software {
  font-size: 0.82rem;
  color: var(--text-muted);
}

.steps-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  position: relative;
}

.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  position: relative;
}

.step-num {
  position: absolute;
  top: -18px;
  left: 24px;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: linear-gradient(135deg, #ff6b35, #ff3366);
  color: #ffffff;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  box-shadow: 0 4px 12px rgba(255, 107, 53, 0.4);
}

.step-card h4 {
  font-size: 1.15rem;
  color: #ffffff;
  margin: 10px 0 10px;
}

.step-card p {
  font-size: 0.92rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* --- 12. 用户真实评价 (User Reviews) --- */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.review-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  backdrop-filter: blur(12px);
  transition: all var(--transition-fast);
}

.review-card:hover {
  border-color: rgba(255, 107, 53, 0.4);
  transform: translateY(-4px);
}

.review-stars {
  color: #fbbf24;
  font-size: 1.1rem;
  margin-bottom: 14px;
  letter-spacing: 2px;
}

.review-text {
  font-size: 0.93rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 22px;
}

.reviewer-info {
  display: flex;
  align-items: center;
  gap: 14px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding-top: 16px;
}

.reviewer-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: linear-gradient(135deg, rgba(255, 107, 53, 0.25), rgba(0, 242, 254, 0.25));
  border: 1.5px solid var(--border-spark);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
  color: #ffffff;
}

.reviewer-meta h5 {
  font-size: 0.96rem;
  color: #ffffff;
  font-weight: 700;
}

.reviewer-meta p {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* --- 13. 常见问题 FAQ (Accordion 手风琴) --- */
.faq-wrap {
  max-width: 860px;
  margin: 0 auto;
}

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

.faq-item:hover {
  border-color: rgba(255, 255, 255, 0.18);
}

.faq-item.active {
  border-color: var(--border-spark);
  background: rgba(22, 34, 62, 0.65);
}

.faq-question {
  width: 100%;
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  text-align: left;
  font-size: 1.05rem;
  font-weight: 600;
  color: #ffffff;
}

.faq-icon {
  font-size: 1.3rem;
  color: var(--spark-primary);
  transition: transform var(--transition-smooth);
}

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

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.3s ease;
  padding: 0 24px;
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

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

/* --- 14. 权威外链与生态工具 (External Links / Partners) --- */
.partners-section {
  padding-top: 50px;
  padding-bottom: 60px;
  border-top: 1px solid var(--border-light);
}

.partners-title {
  text-align: center;
  font-size: 0.88rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 28px;
}

.partners-grid {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
}

.partner-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 18px;
  background: rgba(15, 23, 42, 0.5);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  color: var(--text-muted);
  transition: all var(--transition-fast);
}

.partner-link:hover {
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.3);
  background: rgba(255, 255, 255, 0.05);
  transform: translateY(-2px);
}

/* --- 15. 页脚 (Footer) --- */
.site-footer {
  background: #04060d;
  border-top: 1px solid var(--border-light);
  padding: 64px 0 32px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.footer-top {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-brand img {
  height: 44px;
  width: auto;
  object-fit: contain;
}

.footer-brand p {
  margin-top: 14px;
  line-height: 1.68;
  max-width: 320px;
}

.footer-col h5 {
  font-size: 1rem;
  color: #ffffff;
  font-weight: 700;
  margin-bottom: 18px;
}

.footer-links {
  list-style: none;
}

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

.footer-links a:hover {
  color: var(--spark-primary);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding-top: 28px;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-bottom a {
  color: var(--text-muted);
}

.footer-bottom a:hover {
  color: #ffffff;
}

/* --- 16. 响应式适配 (Media Queries) --- */
@media (max-width: 1180px) {
  .pricing-grid {
    grid-template-columns: repeat(2, 1fr); /* 平板自适应两列两行 */
    gap: 20px;
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .clients-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .node-chips-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 900px) {
  .hero-title {
    font-size: 2.35rem;
    max-width: 100%;
  }
  .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .reviews-grid {
    grid-template-columns: repeat(1, 1fr);
  }
  .steps-container {
    grid-template-columns: 1fr;
    gap: 36px;
  }
  .footer-top {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
}

@media (max-width: 768px) {
  .main-nav {
    display: none;
    position: absolute;
    top: 76px;
    left: 0;
    width: 100%;
    background: rgba(7, 10, 20, 0.98);
    border-bottom: 1px solid var(--border-light);
    flex-direction: column;
    padding: 24px;
    gap: 18px;
    box-shadow: 0 16px 32px rgba(0, 0, 0, 0.6);
  }

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

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

  .hero-title {
    font-size: 1.85rem;
  }

  .title-chunk {
    white-space: normal;
  }

  .hero-subtitle {
    font-size: 1.05rem;
  }

  .pricing-grid {
    grid-template-columns: 1fr; /* 手机端单列 */
  }

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

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

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

  .node-chips-grid {
    grid-template-columns: 1fr;
  }

  .footer-top {
    grid-template-columns: 1fr;
  }

  .section-spacing {
    padding-top: 64px;
    padding-bottom: 64px;
  }

  .hero-trust-bar {
    gap: 20px;
    padding: 16px;
  }
}