```css
/* ==============================================
   油管热浪 · YouTube Flare
   设计系统 — 新波浪粗野主义
   奶油白 × 珊瑚红 × 薄荷绿 × 芥末黄 × 墨黑
   ============================================== */

:root {
  --cream: #FFF9F0;
  --cream-deep: #F5EDE0;
  --ink: #2D3436;
  --coral: #FF6B5B;
  --coral-dark: #E85D4F;
  --teal: #2EC4B6;
  --teal-dark: #27A89C;
  --mustard: #FFD166;
  --light-coral: #FFE8E5;
  --light-teal: #E5F7F5;
  --light-mustard: #FFF1D3;
  --shadow-card: 6px 6px 0 var(--ink);
  --shadow-card-sm: 4px 4px 0 var(--ink);
  --radius-lg: 24px;
  --radius-md: 18px;
  --radius-pill: 50px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: system-ui, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  overflow-x: hidden;
  background: var(--cream);
  color: var(--ink);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ---------- 核心布局 ---------- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 90px 0;
  position: relative;
}

.section:nth-child(even) {
  background-color: var(--cream-deep);
  background-image: radial-gradient(rgba(45, 52, 54, 0.07) 1.5px, transparent 1.5px);
  background-size: 28px 28px;
}

/* ---------- 导航头部 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(255, 249, 240, 0.93);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 2px solid var(--ink);
  transition: box-shadow 0.3s ease;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 1.25rem;
  text-decoration: none;
  color: var(--ink);
  letter-spacing: -0.02em;
}

.logo-icon {
  width: 40px;
  height: 40px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  background: linear-gradient(135deg, var(--coral) 0%, #FF8A75 100%);
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 var(--ink);
  color: #fff;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.main-nav a {
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  transition: color 0.2s;
  color: var(--ink);
  position: relative;
  padding: 6px 0;
}

.main-nav a:not(.nav-cta)::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 3px;
  background: var(--coral);
  border-radius: 3px;
  transition: width 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.main-nav a:not(.nav-cta):hover::after {
  width: 100%;
}

.main-nav a:not(.nav-cta):hover {
  color: var(--coral);
}

.nav-cta {
  padding: 10px 24px;
  border-radius: var(--radius-pill);
  color: #fff !important;
  font-weight: 700;
  background: var(--teal);
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 var(--ink);
  transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.nav-cta:hover {
  transform: translate(2px, 2px);
  box-shadow: 1px 1px 0 var(--ink);
  color: #fff !important;
}

.menu-toggle {
  display: none;
}

/* ---------- Hero 首屏 ---------- */
.hero {
  min-height: 70vh;
  display: flex;
  align-items: center;
  gap: 64px;
  padding: 150px 0 100px;
  position: relative;
  background-image: radial-gradient(rgba(45, 52, 54, 0.05) 1.5px, transparent 1.5px);
  background-size: 48px 48px;
}

.hero-content {
  max-width: 720px;
  flex: 1;
  position: relative;
  z-index: 2;
}

.hero-eyebrow {
  display: inline-block;
  font-size: 0.82rem;
  font-weight: 800;
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  margin-bottom: 24px;
  background: var(--mustard);
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 var(--ink);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  transform: rotate(-2deg);
  transition: all 0.3s;
}

.hero-eyebrow:hover {
  transform: rotate(0deg) translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--ink);
}

.hero h1 {
  font-size: clamp(2.5rem, 5.5vw, 4rem);
  line-height: 1.15;
  margin-bottom: 24px;
  font-weight: 800;
  letter-spacing: -0.03em;
}

.hero h1 strong {
  color: var(--coral);
  font-weight: 800;
}

.hero p {
  font-size: 1.15rem;
  opacity: 0.7;
  max-width: 560px;
  margin-bottom: 36px;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-image {
  flex-shrink: 0;
  width: 42%;
  max-width: 460px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 3px solid var(--ink);
  box-shadow: 12px 12px 0 var(--ink);
  background: var(--light-teal);
  transform: rotate(2deg);
  position: relative;
  transition: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.hero-image:hover {
  transform: rotate(0deg) translate(-3px, -3px);
  box-shadow: 14px 14px 0 var(--ink);
}

.hero-image img {
  width: 100%;
  height: auto;
  display: block;
}

.hero-image::after {
  content: '▶';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 72px;
  height: 72px;
  background: var(--coral);
  border: 3px solid var(--ink);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-left: 4px;
  font-size: 1.3rem;
  color: #fff;
  box-shadow: 4px 4px 0 var(--ink);
  transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  line-height: 1;
}

.hero-image:hover::after {
  transform: translate(-50%, -50%) scale(1.12);
  background: var(--teal);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: var(--radius-pill);
  font-weight: 700;
  cursor: pointer;
  border: 2px solid var(--ink);
  text-decoration: none;
  transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
  font-size: 0.95rem;
}

.btn-primary {
  background: var(--coral);
  color: #fff;
  box-shadow: 4px 4px 0 var(--ink);
}

.btn-primary:hover {
  transform: translate(2px, 2px);
  box-shadow: 2px 2px 0 var(--ink);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--ink);
  color: var(--ink);
  box-shadow: 4px 4px 0 var(--ink);
}

.btn-outline:hover {
  transform: translate(2px, 2px);
  box-shadow: 2px 2px 0 var(--ink);
  background: var(--light-mustard);
}

/* ---------- 标签 / 标题 ---------- */
.section-label {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 2px;
  margin-bottom: 16px;
  text-transform: uppercase;
  color: var(--ink);
  background: var(--light-coral);
  padding: 6px 18px;
  border-radius: var(--radius-pill);
  border: 2px solid var(--ink);
  box-shadow: 2px 2px 0 var(--ink);
}

.section-title {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 14px;
  letter-spacing: -0.02em;
  line-height: 1.3;
}

.section-title::after {
  content: '';
  display: block;
  width: 56px;
  height: 6px;
  background: var(--coral);
  border-radius: 6px;
  margin-top: 10px;
}

.text-center .section-title::after {
  margin: 10px auto 0;
}

.section-desc {
  max-width: 600px;
  opacity: 0.7;
  margin-bottom: 44px;
  font-size: 1.05rem;
  line-height: 1.7;
}

/* ---------- 卡片网格 ---------- */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 28px;
}

.category-card {
  border-radius: var(--radius-md);
  padding: 32px 28px;
  border: 2px solid var(--ink);
  background: #fff;
  box-shadow: var(--shadow-card);
  transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  position: relative;
  overflow: hidden;
}

.category-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 20px;
  right: 20px;
  height: 6px;
  border-radius: 0 0 6px 6px;
  background: var(--coral);
}

.category-card:nth-child(3n+2)::before {
  background: var(--teal);
}

.category-card:nth-child(3n+3)::before {
  background: var(--mustard);
}

.category-card:hover {
  transform: translate(-2px, -6px);
  box-shadow: 8px 10px 0 var(--ink);
}

.card-icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
  font-size: 1.5rem;
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 var(--ink);
}

.category-card:nth-child(3n+1) .card-icon {
  background: var(--light-coral);
}

.category-card:nth-child(3n+2) .card-icon {
  background: var(--light-mustard);
}

.category-card:nth-child(3n+3) .card-icon {
  background: var(--light-teal);
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 700;
  font-size: 0.85rem;
  text-decoration: none;
  color: var(--ink);
  transition: color 0.2s;
}

.card-link::after {
  content: '→';
  font-size: 1rem;
  transition: transform 0.2s;
}

.card-link:hover {
  color: var(--coral);
}

.card-link:hover::after {
  transform: translateX(4px);
}

/* ---------- 特性块 ---------- */
.feature-block {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

.feature-image {
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 3px solid var(--ink);
  box-shadow: 10px 10px 0 var(--ink);
  transition: all 0.3s ease;
  position: relative;
}

.feature-image:hover {
  transform: translate(-2px, -4px);
  box-shadow: 12px 14px 0 var(--ink);
}

.feature-image img {
  width: 100%;
  height: auto;
  display: block;
}

.feature-text {
  position: relative;
}

.feature-list {
  list-style: none;
}

.feature-list li {
  padding: 8px 0;
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 500;
  font-size: 0.95rem;
}

.feature-list li::before {
  content: '✓';
  font-weight: 800;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--teal);
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  border: 2px solid var(--ink);
  box-shadow: 2px 2px 0 var(--ink);
  flex-shrink: 0;
}

/* ---------- 数据条 ---------- */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  text-align: center;
}

.stat-item {
  padding: 32px 16px;
  border-radius: var(--radius-md);
  border: 2px solid var(--ink);
  background: #fff;
  box-shadow: var(--shadow-card-sm);
  position: relative;
  overflow: hidden;
  transition: transform 0.3s, box-shadow 0.3s;
}

.stat-item:hover {
  transform: translate(-2px, -2px);
  box-shadow: 6px 6px 0 var(--ink);
}

.stat-item::before {
  content: '';
  position: absolute;
  top: -10px;
  right: -10px;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--mustard);
  border: 2px solid var(--ink);
}

.stat-item:nth-child(1) {
  background: var(--light-coral);
}

.stat-item:nth-child(2) {
  background: var(--light-mustard);
}

.stat-item:nth-child(3) {
  background: var(--light-teal);
}

.stat-item:nth-child(4) {
  background: #fff;
}

.stat-number {
  font-size: 2.8rem;
  font-weight: