/* ============================================
   推特 品牌官网 - 原创样式表
   全球社交媒体平台 | grbnem.cn
   ============================================ */

/* === CSS Variables === */
:root {
  --primary: #1A1A2E;
  --secondary: #E94560;
  --accent: #0F3460;
  --bg-dark: #16213E;
  --bg-darker: #0D1321;
  --text-light: #EAEAEA;
  --text-muted: #A0A0B8;
  --purple: #533483;
  --gold: #C9A84C;
  --gradient-1: linear-gradient(135deg, #1A1A2E 0%, #16213E 50%, #0F3460 100%);
  --gradient-2: linear-gradient(135deg, #E94560 0%, #533483 100%);
  --gradient-3: linear-gradient(180deg, rgba(26,26,46,0.95) 0%, rgba(22,33,62,0.9) 100%);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* === Reset & Base === */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg-darker);
  color: var(--text-light);
  line-height: 1.7;
  overflow-x: hidden;
}

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

a:hover {
  color: var(--gold);
}

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

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-light);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* === Header & Navigation === */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(13, 19, 33, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(233, 69, 96, 0.2);
  transition: var(--transition);
}

.site-header.scrolled {
  background: rgba(13, 19, 33, 0.98);
  box-shadow: var(--shadow-md);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo img {
  height: 45px;
  width: 45px;
  border-radius: 50%;
}

.logo-text {
  font-size: 1.6rem;
  font-weight: 800;
  background: var(--gradient-2);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 0;
}

.main-nav a {
  color: var(--text-light);
  padding: 8px 16px;
  font-size: 0.95rem;
  font-weight: 500;
  position: relative;
  white-space: nowrap;
}

.main-nav a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background: var(--secondary);
  transition: var(--transition);
}

.main-nav a:hover::after,
.main-nav a.active::after {
  width: 70%;
}

.main-nav a:hover {
  color: var(--secondary);
}

.mobile-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 5px;
}

.mobile-toggle span {
  width: 25px;
  height: 2px;
  background: var(--text-light);
  transition: var(--transition);
}

/* === Search Bar === */
.search-bar-wrap {
  background: var(--bg-dark);
  padding: 12px 0;
  border-bottom: 1px solid rgba(255,255,255,0.05);
}

.search-bar {
  max-width: 600px;
  margin: 0 auto;
  position: relative;
}

.search-bar input {
  width: 100%;
  padding: 12px 50px 12px 20px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(233, 69, 96, 0.3);
  border-radius: 30px;
  color: var(--text-light);
  font-size: 0.95rem;
  outline: none;
  transition: var(--transition);
}

.search-bar input:focus {
  border-color: var(--secondary);
  background: rgba(255,255,255,0.12);
  box-shadow: 0 0 20px rgba(233, 69, 96, 0.15);
}

.search-bar input::placeholder {
  color: var(--text-muted);
}

.search-bar button {
  position: absolute;
  right: 5px;
  top: 50%;
  transform: translateY(-50%);
  background: var(--secondary);
  border: none;
  color: #fff;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1rem;
  transition: var(--transition);
}

.search-bar button:hover {
  background: #d63851;
  transform: translateY(-50%) scale(1.05);
}

/* === Banner / Hero === */
.hero-banner {
  position: relative;
  min-height: 85vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  margin-top: 70px;
}

.hero-banner .hero-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  filter: brightness(0.4);
  transform: scale(1.05);
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 800px;
  padding: 40px 20px;
}

.hero-content h1 {
  font-size: 3rem;
  margin-bottom: 20px;
  text-shadow: 0 4px 20px rgba(0,0,0,0.5);
}

.hero-content h1 span {
  color: var(--secondary);
}

.hero-content p {
  font-size: 1.15rem;
  color: var(--text-muted);
  margin-bottom: 30px;
  line-height: 1.8;
}

.hero-btns {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: 30px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  border: none;
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient-2);
  color: #fff;
  box-shadow: 0 4px 15px rgba(233, 69, 96, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(233, 69, 96, 0.6);
  color: #fff;
}

.btn-outline {
  background: transparent;
  color: var(--text-light);
  border: 2px solid rgba(255,255,255,0.3);
}

.btn-outline:hover {
  border-color: var(--secondary);
  color: var(--secondary);
  transform: translateY(-2px);
}

/* === Section Common === */
.section {
  padding: 80px 0;
}

.section-alt {
  background: var(--bg-dark);
}

.section-title {
  text-align: center;
  margin-bottom: 50px;
}

.section-title h2 {
  font-size: 2.2rem;
  margin-bottom: 12px;
  position: relative;
  display: inline-block;
}

.section-title h2::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--gradient-2);
  border-radius: 3px;
}

.section-title p {
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-top: 16px;
}

/* === Video Cards === */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}

.video-card {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid rgba(255,255,255,0.06);
  transition: var(--transition);
  cursor: pointer;
}

.video-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(233, 69, 96, 0.3);
}

.video-thumb {
  position: relative;
  padding-top: 56.25%;
  overflow: hidden;
}

.video-thumb img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.video-card:hover .video-thumb img {
  transform: scale(1.08);
}

.play-btn {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0.8);
  width: 60px;
  height: 60px;
  background: rgba(233, 69, 96, 0.9);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: var(--transition);
  z-index: 2;
}

.play-btn::after {
  content: '';
  width: 0;
  height: 0;
  border-style: solid;
  border-width: 10px 0 10px 18px;
  border-color: transparent transparent transparent #fff;
  margin-left: 4px;
}

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

.video-duration {
  position: absolute;
  bottom: 8px;
  right: 8px;
  background: rgba(0,0,0,0.8);
  color: #fff;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.8rem;
  z-index: 2;
}

.video-info {
  padding: 16px;
}

.video-info h3 {
  font-size: 1rem;
  margin-bottom: 8px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.video-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.video-tags {
  display: flex;
  gap: 6px;
  margin-top: 10px;
  flex-wrap: wrap;
}

.video-tags span {
  background: rgba(233, 69, 96, 0.15);
  color: var(--secondary);
  padding: 2px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
}

/* === Feature Grid === */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.feature-card {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  padding: 30px;
  border: 1px solid rgba(255,255,255,0.06);
  transition: var(--transition);
  text-align: center;
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: rgba(233, 69, 96, 0.3);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 20px;
  background: var(--gradient-2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
}

.feature-card h3 {
  font-size: 1.15rem;
  margin-bottom: 10px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* === Expert / Team Cards === */
.team-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
}

.team-card {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid rgba(255,255,255,0.06);
  transition: var(--transition);
  text-align: center;
}

.team-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.team-card .team-photo {
  width: 100%;
  height: 280px;
  object-fit: cover;
}

.team-card .team-info {
  padding: 20px;
}

.team-card h3 {
  font-size: 1.1rem;
  margin-bottom: 4px;
}

.team-card .role {
  color: var(--secondary);
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.team-card p {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-bottom: 12px;
}

.team-links {
  display: flex;
  gap: 10px;
  justify-content: center;
}

.team-links a {
  padding: 6px 14px;
  border: 1px solid rgba(233, 69, 96, 0.4);
  border-radius: 20px;
  font-size: 0.8rem;
  color: var(--secondary);
}

.team-links a:hover {
  background: var(--secondary);
  color: #fff;
}

/* === Partner Logos === */
.partner-section img {
  width: 100%;
  border-radius: var(--radius-md);
  border: 1px solid rgba(255,255,255,0.06);
}

/* === FAQ === */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-question {
  padding: 18px 24px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  font-size: 1rem;
  transition: var(--transition);
}

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

.faq-question .faq-toggle {
  font-size: 1.4rem;
  transition: transform 0.3s ease;
  color: var(--secondary);
}

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

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
}

.faq-answer-inner {
  padding: 0 24px 18px;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.8;
}

.faq-item.active .faq-answer {
  max-height: 500px;
}

/* === Reviews === */
.review-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.review-card {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid rgba(255,255,255,0.06);
}

.review-stars {
  color: var(--gold);
  font-size: 1rem;
  margin-bottom: 12px;
}

.review-text {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 16px;
  line-height: 1.7;
  font-style: italic;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 10px;
}

.review-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--gradient-2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.9rem;
  color: #fff;
}

.review-author-info .name {
  font-weight: 600;
  font-size: 0.9rem;
}

.review-author-info .date {
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* === Contact Section === */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 30px;
}

.contact-card {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  padding: 30px;
  border: 1px solid rgba(255,255,255,0.06);
}

.contact-card h3 {
  font-size: 1.15rem;
  margin-bottom: 16px;
  color: var(--secondary);
}

.contact-card p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 8px;
}

.contact-card img {
  max-width: 180px;
  margin: 12px auto 0;
  border-radius: var(--radius-sm);
}

/* === How-To Guide === */
.howto-steps {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 24px;
  counter-reset: step;
}

.howto-step {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  padding: 30px;
  border: 1px solid rgba(255,255,255,0.06);
  position: relative;
  counter-increment: step;
}

.howto-step::before {
  content: counter(step);
  position: absolute;
  top: -12px;
  left: 20px;
  width: 36px;
  height: 36px;
  background: var(--gradient-2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
}

.howto-step h4 {
  margin-bottom: 8px;
  margin-top: 8px;
}

.howto-step p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* === Share Buttons === */
.share-bar {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  padding: 20px 0;
}

.share-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
  color: #fff;
  transition: var(--transition);
}

.share-btn:hover {
  transform: translateY(-2px);
  color: #fff;
}

.share-wechat { background: #07C160; }
.share-weibo { background: #E6162D; }
.share-douyin { background: #161823; border: 1px solid #333; }
.share-bilibili { background: #00A1D6; }

/* === Footer === */
.site-footer {
  background: var(--bg-darker);
  border-top: 1px solid rgba(255,255,255,0.06);
  padding: 50px 0 20px;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 30px;
  margin-bottom: 30px;
}

.footer-col h4 {
  font-size: 1rem;
  margin-bottom: 16px;
  color: var(--secondary);
}

.footer-col p,
.footer-col a {
  color: var(--text-muted);
  font-size: 0.9rem;
  display: block;
  margin-bottom: 8px;
}

.footer-col a:hover {
  color: var(--secondary);
}

.footer-col img.footer-logo {
  height: 40px;
  width: 40px;
  border-radius: 50%;
  margin-bottom: 12px;
}

.footer-col img.qr-img {
  width: 120px;
  border-radius: var(--radius-sm);
  margin-top: 8px;
}

.footer-bottom {
  text-align: center;
  padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,0.06);
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* === Breadcrumb === */
.breadcrumb {
  padding: 15px 0;
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: 70px;
}

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

.breadcrumb a:hover {
  color: var(--secondary);
}

.breadcrumb span {
  margin: 0 8px;
  color: rgba(255,255,255,0.3);
}

/* === Inner Page Hero === */
.inner-hero {
  background: var(--gradient-1);
  padding: 60px 0 40px;
  margin-top: 70px;
  text-align: center;
}

.inner-hero h1 {
  font-size: 2.2rem;
  margin-bottom: 10px;
}

.inner-hero p {
  color: var(--text-muted);
  font-size: 1.05rem;
}

/* === Community Cards === */
.community-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}

.community-card {
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid rgba(255,255,255,0.06);
  transition: var(--transition);
}

.community-card:hover {
  border-color: rgba(233, 69, 96, 0.3);
  transform: translateY(-3px);
}

.community-card h3 {
  font-size: 1.1rem;
  margin-bottom: 10px;
}

.community-card p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 12px;
}

.community-stats {
  display: flex;
  gap: 16px;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* === AI Section === */
.ai-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: center;
}

.ai-grid img {
  border-radius: var(--radius-md);
  border: 1px solid rgba(255,255,255,0.06);
}

.ai-features {
  list-style: none;
}

.ai-features li {
  padding: 12px 0;
  border-bottom: 1px solid rgba(255,255,255,0.06);
  color: var(--text-muted);
  font-size: 0.95rem;
  padding-left: 24px;
  position: relative;
}

.ai-features li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--secondary);
}

/* === MCP Frontend Mock === */
.mcp-widget {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: var(--radius-md);
  padding: 20px;
  margin-top: 20px;
}

.mcp-widget .mcp-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  font-weight: 600;
  color: var(--secondary);
}

.mcp-widget .mcp-status {
  display: inline-block;
  width: 8px;
  height: 8px;
  background: #07C160;
  border-radius: 50%;
}

.mcp-widget .mcp-body {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* === Lazy Load Placeholder === */
.lazy-img {
  opacity: 0;
  transition: opacity 0.5s ease;
}

.lazy-img.loaded {
  opacity: 1;
}

/* === Responsive === */
@media (max-width: 768px) {
  .hero-content h1 {
    font-size: 2rem;
  }

  .hero-banner {
    min-height: 70vh;
  }

  .main-nav {
    display: none;
    position: fixed;
    top: 70px;
    left: 0;
    width: 100%;
    background: rgba(13, 19, 33, 0.98);
    flex-direction: column;
    padding: 20px;
    gap: 0;
    border-bottom: 1px solid rgba(233, 69, 96, 0.2);
  }

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

  .main-nav a {
    padding: 12px 16px;
    border-bottom: 1px solid rgba(255,255,255,0.05);
    width: 100%;
  }

  .mobile-toggle {
    display: flex;
  }

  .section {
    padding: 50px 0;
  }

  .section-title h2 {
    font-size: 1.6rem;
  }

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

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

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

  .hero-btns {
    flex-direction: column;
    align-items: center;
  }

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

@media (max-width: 480px) {
  .header-inner {
    height: 60px;
  }

  .hero-banner {
    margin-top: 60px;
    min-height: 60vh;
  }

  .breadcrumb {
    margin-top: 60px;
  }

  .inner-hero {
    margin-top: 60px;
    padding: 40px 0 30px;
  }

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

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

/* === Scrollbar === */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-darker);
}

::-webkit-scrollbar-thumb {
  background: var(--accent);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--secondary);
}

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

.animate-in {
  animation: fadeInUp 0.6s ease forwards;
}