/* 
 * 51视频 - 现代科技感 + 动漫社区融合设计
 * 色彩方案：深紫蓝 #1a1a2e + 亮紫粉 #ff006e + 天蓝 #00d4ff + 金色 #ffd60a
 * 字体：Poppins (标题) + Noto Sans SC (正文)
 */

/* ==================== 全局样式 ==================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600;700;800&family=Noto+Sans+SC:wght@400;500;600;700&display=swap');

:root {
  --primary-dark: #1a1a2e;
  --primary-blue: #2d3561;
  --accent-pink: #ff006e;
  --accent-cyan: #00d4ff;
  --accent-gold: #ffd60a;
  --text-light: #f8f9fa;
  --text-dark: #0a0e27;
  --border-light: rgba(255, 255, 255, 0.1);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.15);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.25);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.35);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Noto Sans SC', sans-serif;
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-blue) 100%);
  color: var(--text-light);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
}

/* ==================== 排版 ==================== */
h1, h2, h3, h4, h5, h6 {
  font-family: 'Poppins', sans-serif;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: -0.5px;
}

h1 {
  font-size: 3.5rem;
  line-height: 1.2;
  background: linear-gradient(135deg, var(--accent-pink), var(--accent-cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

h2 {
  font-size: 2.5rem;
  line-height: 1.2;
}

h3 {
  font-size: 1.75rem;
  line-height: 1.3;
}

h4 {
  font-size: 1.5rem;
}

h5 {
  font-size: 1.25rem;
}

h6 {
  font-size: 1rem;
}

p {
  font-size: 1rem;
  line-height: 1.6;
  margin-bottom: 1rem;
}

a {
  color: var(--accent-cyan);
  text-decoration: none;
  transition: all 0.3s ease;
}

a:hover {
  color: var(--accent-pink);
  text-shadow: 0 0 10px rgba(255, 0, 110, 0.5);
}

/* ==================== 容器与布局 ==================== */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 2rem;
}

@media (max-width: 768px) {
  .container {
    padding: 0 1rem;
  }
}

.section {
  padding: 5rem 0;
}

@media (max-width: 768px) {
  .section {
    padding: 3rem 0;
  }
}

/* ==================== 导航栏 ==================== */
header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(26, 26, 46, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-light);
  padding: 1rem 0;
}

nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-pink), var(--accent-cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo::before {
  content: '▶';
  font-size: 1.2rem;
}

.nav-menu {
  display: flex;
  gap: 2rem;
  list-style: none;
  align-items: center;
}

.nav-menu a {
  color: var(--text-light);
  font-weight: 500;
  position: relative;
  padding: 0.5rem 0;
}

.nav-menu a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-pink), var(--accent-cyan));
  transition: width 0.3s ease;
}

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

.search-box {
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid var(--border-light);
  border-radius: 50px;
  padding: 0.5rem 1rem;
  gap: 0.5rem;
  cursor: pointer;
  transition: all 0.3s ease;
}

.search-box:hover {
  background: rgba(255, 255, 255, 0.15);
  border-color: var(--accent-cyan);
}

.search-box input {
  background: transparent;
  border: none;
  color: var(--text-light);
  outline: none;
  width: 200px;
  font-size: 0.9rem;
}

.search-box input::placeholder {
  color: rgba(255, 255, 255, 0.5);
}

.sign-in-btn {
  background: linear-gradient(135deg, var(--accent-pink), #ff3d7f);
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: 50px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(255, 0, 110, 0.3);
}

.sign-in-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(255, 0, 110, 0.4);
}

@media (max-width: 768px) {
  .nav-menu {
    gap: 1rem;
    font-size: 0.9rem;
  }
  
  .search-box input {
    width: 120px;
  }
  
  .sign-in-btn {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
  }
}

/* ==================== 英雄区 ==================== */
.hero {
  margin-top: 70px;
  background: linear-gradient(135deg, rgba(26, 26, 46, 0.8), rgba(45, 53, 97, 0.8)), 
              url('https://d2xsxph8kpxj0f.cloudfront.net/310519663692640375/Z4NiLynnKzYugHSrYCS76c/hero-banner-JKudWCQSZUbpajqDSM7SAF.webp');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  min-height: 600px;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 20% 50%, rgba(255, 0, 110, 0.1) 0%, transparent 50%),
              radial-gradient(circle at 80% 80%, rgba(0, 212, 255, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 2;
  animation: slideInUp 0.8s ease-out;
}

.hero h1 {
  font-size: 4rem;
  margin-bottom: 1rem;
  text-shadow: 0 0 30px rgba(255, 0, 110, 0.3);
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-light);
  margin-bottom: 2rem;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.btn {
  padding: 1rem 2rem;
  border-radius: 50px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  border: none;
  font-size: 1rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-pink), #ff3d7f);
  color: white;
  box-shadow: 0 8px 25px rgba(255, 0, 110, 0.3);
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 35px rgba(255, 0, 110, 0.4);
}

.btn-secondary {
  background: transparent;
  color: var(--text-light);
  border: 2px solid var(--accent-cyan);
}

.btn-secondary:hover {
  background: rgba(0, 212, 255, 0.1);
  border-color: var(--accent-pink);
  color: var(--accent-pink);
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin-top: 3rem;
}

.stat-item {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-light);
  border-radius: 15px;
  padding: 1.5rem;
  backdrop-filter: blur(10px);
  text-align: center;
  transition: all 0.3s ease;
}

.stat-item:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--accent-cyan);
  transform: translateY(-5px);
}

.stat-number {
  font-size: 2rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-pink), var(--accent-cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  font-size: 0.9rem;
  color: rgba(255, 255, 255, 0.7);
  margin-top: 0.5rem;
}

@media (max-width: 768px) {
  .hero {
    min-height: 400px;
    margin-top: 60px;
  }
  
  .hero h1 {
    font-size: 2.5rem;
  }
  
  .hero-subtitle {
    font-size: 1rem;
  }
  
  .hero-buttons {
    flex-direction: column;
  }
  
  .hero-stats {
    grid-template-columns: 1fr;
  }
}

/* ==================== 卡片样式 ==================== */
.card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-light);
  border-radius: 15px;
  padding: 1.5rem;
  backdrop-filter: blur(10px);
  transition: all 0.3s ease;
  overflow: hidden;
  position: relative;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-pink), var(--accent-cyan), transparent);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.card:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--accent-cyan);
  transform: translateY(-8px);
  box-shadow: 0 20px 40px rgba(0, 212, 255, 0.2);
}

.card:hover::before {
  opacity: 1;
}

/* ==================== 视频卡片 ==================== */
.video-card {
  position: relative;
  border-radius: 15px;
  overflow: hidden;
  cursor: pointer;
  group: 'video';
}

.video-thumbnail {
  width: 100%;
  height: 200px;
  background: linear-gradient(135deg, var(--primary-blue), var(--primary-dark));
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.video-thumbnail img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.3s ease;
}

.video-card:hover .video-thumbnail img {
  transform: scale(1.05);
}

.play-button {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--accent-pink), #ff3d7f);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: all 0.3s ease;
  box-shadow: 0 0 20px rgba(255, 0, 110, 0.5);
}

.play-button::after {
  content: '▶';
  color: white;
  font-size: 1.5rem;
  margin-left: 3px;
}

.video-card:hover .play-button {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1.1);
}

.video-info {
  padding: 1rem;
  background: rgba(26, 26, 46, 0.8);
}

.video-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-light);
}

.video-stats {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.6);
}

.stat {
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

/* ==================== 网格布局 ==================== */
.grid {
  display: grid;
  gap: 2rem;
}

.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.grid-4 {
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

@media (max-width: 768px) {
  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }
}

/* ==================== 模块标题 ==================== */
.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-title {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.section-subtitle {
  font-size: 1.1rem;
  color: rgba(255, 255, 255, 0.7);
  max-width: 600px;
  margin: 0 auto;
}

/* ==================== 专家展示 ==================== */
.expert-card {
  text-align: center;
}

.expert-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  margin: 0 auto 1rem;
  background: linear-gradient(135deg, var(--accent-pink), var(--accent-cyan));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  box-shadow: 0 0 30px rgba(255, 0, 110, 0.3);
}

.expert-name {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.expert-title {
  color: var(--accent-cyan);
  font-size: 0.9rem;
  margin-bottom: 1rem;
}

.expert-bio {
  font-size: 0.95rem;
  color: rgba(255, 255, 255, 0.7);
  margin-bottom: 1rem;
  line-height: 1.6;
}

.expert-links {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

.expert-btn {
  padding: 0.5rem 1rem;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid var(--border-light);
  border-radius: 25px;
  color: var(--text-light);
  cursor: pointer;
  transition: all 0.3s ease;
  font-size: 0.85rem;
}

.expert-btn:hover {
  background: var(--accent-cyan);
  border-color: var(--accent-cyan);
  color: var(--text-dark);
}

/* ==================== FAQ ==================== */
.faq-item {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-light);
  border-radius: 10px;
  margin-bottom: 1rem;
  overflow: hidden;
  transition: all 0.3s ease;
}

.faq-question {
  padding: 1.5rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  transition: all 0.3s ease;
}

.faq-question:hover {
  background: rgba(255, 255, 255, 0.1);
  color: var(--accent-cyan);
}

.faq-toggle {
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.3s ease;
}

.faq-item.active .faq-toggle {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  padding: 0 1.5rem;
}

.faq-item.active .faq-answer {
  max-height: 500px;
  padding: 0 1.5rem 1.5rem;
}

.faq-answer p {
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: 0;
}

/* ==================== 用户评论 ==================== */
.review-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-light);
  border-radius: 15px;
  padding: 2rem;
  position: relative;
}

.review-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.review-avatar {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-pink), var(--accent-cyan));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.review-user {
  flex: 1;
}

.review-name {
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.review-role {
  font-size: 0.85rem;
  color: var(--accent-cyan);
}

.review-rating {
  display: flex;
  gap: 0.25rem;
}

.star {
  color: var(--accent-gold);;
  font-size: 1rem;
}

.review-text {
  color: rgba(255, 255, 255, 0.8);
  line-height: 1.6;
  margin-bottom: 1rem;
}

.review-quote {
  position: absolute;
  top: 1rem;
  right: 1.5rem;
  font-size: 3rem;
  opacity: 0.1;
  color: var(--accent-pink);
}

/* ==================== 页脚 ==================== */
footer {
  background: rgba(26, 26, 46, 0.95);
  border-top: 1px solid var(--border-light);
  padding: 3rem 0 1rem;
  margin-top: 5rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-section h4 {
  margin-bottom: 1rem;
  color: var(--accent-cyan);
}

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

.footer-section ul li {
  margin-bottom: 0.5rem;
}

.footer-section a {
  color: rgba(255, 255, 255, 0.7);
  transition: all 0.3s ease;
}

.footer-section a:hover {
  color: var(--accent-pink);
}

.footer-bottom {
  border-top: 1px solid var(--border-light);
  padding-top: 2rem;
  text-align: center;
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.9rem;
}

.footer-qr {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1rem;
}

.qr-item {
  text-align: center;
}

.qr-code {
  width: 100px;
  height: 100px;
  background: white;
  border-radius: 10px;
  padding: 5px;
  margin-bottom: 0.5rem;
}

.qr-label {
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.7);
}

/* ==================== 动画 ==================== */
@keyframes slideInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

@keyframes glow {
  0%, 100% {
    box-shadow: 0 0 10px rgba(255, 0, 110, 0.3);
  }
  50% {
    box-shadow: 0 0 20px rgba(255, 0, 110, 0.6);
  }
}

.animate-in {
  animation: slideInUp 0.6s ease-out;
}

.animate-pulse {
  animation: pulse 2s infinite;
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 1024px) {
  .container {
    padding: 0 1.5rem;
  }
  
  h1 {
    font-size: 2.5rem;
  }
  
  h2 {
    font-size: 2rem;
  }
}

@media (max-width: 768px) {
  header {
    padding: 0.75rem 0;
  }
  
  .nav-menu {
    gap: 1rem;
  }
  
  .search-box {
    display: none;
  }
  
  .logo {
    font-size: 1.25rem;
  }
  
  .section {
    padding: 2rem 0;
  }
}

/* ==================== 工具类 ==================== */
.text-center {
  text-align: center;
}

.text-left {
  text-align: left;
}

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

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mt-5 { margin-top: 3rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.mb-5 { margin-bottom: 3rem; }

.opacity-50 { opacity: 0.5; }
.opacity-75 { opacity: 0.75; }

.hidden {
  display: none;
}

.visible {
  display: block;
}