/* ============================================
   困困兔 - 汽车改装视频社区 样式表
   品牌：困困兔 | 域名：469646.cn
   原创设计 - 赛车风格配色方案
   ============================================ */

/* === CSS Variables === */
:root {
  --kkt-red: #E63946;
  --kkt-navy: #1D3557;
  --kkt-amber: #F4A261;
  --kkt-mint: #F1FAEE;
  --kkt-dark: #0D1117;
  --kkt-gray: #2B2D42;
  --kkt-light-gray: #8D99AE;
  --kkt-border: #2A2E3A;
  --kkt-card-bg: #161B22;
  --kkt-gradient-red: linear-gradient(135deg, #E63946 0%, #C1121F 100%);
  --kkt-gradient-navy: linear-gradient(135deg, #1D3557 0%, #0D1B2A 100%);
  --kkt-gradient-dark: linear-gradient(180deg, #0D1117 0%, #161B22 100%);
  --kkt-shadow: 0 4px 24px rgba(0,0,0,0.3);
  --kkt-shadow-hover: 0 8px 40px rgba(230,57,70,0.2);
  --kkt-radius: 12px;
  --kkt-radius-sm: 8px;
  --kkt-transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background-color: var(--kkt-dark);
  color: var(--kkt-mint);
  line-height: 1.7;
  overflow-x: hidden;
}
a { color: var(--kkt-amber); text-decoration: none; transition: var(--kkt-transition); }
a:hover { color: var(--kkt-red); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }
h1, h2, h3, h4, h5, h6 { font-weight: 700; line-height: 1.3; color: #fff; }

/* === Container === */
.kkt-container { max-width: 1280px; margin: 0 auto; padding: 0 20px; }
.kkt-section { padding: 80px 0; }
.kkt-section-dark { background: var(--kkt-gradient-dark); }
.kkt-section-navy { background: var(--kkt-gradient-navy); }

/* === Header / Navigation === */
.kkt-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(13,17,23,0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--kkt-border);
  transition: var(--kkt-transition);
}
.kkt-header.scrolled { box-shadow: 0 2px 20px rgba(0,0,0,0.5); }
.kkt-header-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1280px; margin: 0 auto; padding: 0 20px; height: 70px;
}
.kkt-logo { display: flex; align-items: center; gap: 10px; }
.kkt-logo img { height: 42px; width: auto; }
.kkt-logo-text { font-size: 1.4rem; font-weight: 800; color: #fff; letter-spacing: 1px; }
.kkt-logo-text span { color: var(--kkt-red); }

.kkt-nav { display: flex; align-items: center; gap: 0; }
.kkt-nav a {
  padding: 8px 16px; font-size: 0.95rem; color: var(--kkt-light-gray);
  position: relative; white-space: nowrap;
}
.kkt-nav a::after {
  content: ''; position: absolute; bottom: 0; left: 50%; width: 0; height: 2px;
  background: var(--kkt-red); transition: var(--kkt-transition); transform: translateX(-50%);
}
.kkt-nav a:hover, .kkt-nav a.active { color: #fff; }
.kkt-nav a:hover::after, .kkt-nav a.active::after { width: 60%; }

.kkt-mobile-toggle { display: none; cursor: pointer; padding: 8px; }
.kkt-mobile-toggle span {
  display: block; width: 24px; height: 2px; background: #fff;
  margin: 5px 0; transition: var(--kkt-transition);
}

/* === Search Bar === */
.kkt-search-bar {
  background: var(--kkt-card-bg); border-bottom: 1px solid var(--kkt-border);
  padding: 12px 0; margin-top: 70px;
}
.kkt-search-inner {
  max-width: 1280px; margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; gap: 12px;
}
.kkt-search-input {
  flex: 1; background: var(--kkt-dark); border: 1px solid var(--kkt-border);
  border-radius: 24px; padding: 10px 20px; color: #fff; font-size: 0.95rem;
  outline: none; transition: var(--kkt-transition);
}
.kkt-search-input:focus { border-color: var(--kkt-red); box-shadow: 0 0 0 3px rgba(230,57,70,0.15); }
.kkt-search-input::placeholder { color: var(--kkt-light-gray); }
.kkt-search-btn {
  background: var(--kkt-gradient-red); border: none; border-radius: 24px;
  padding: 10px 28px; color: #fff; font-size: 0.95rem; cursor: pointer;
  transition: var(--kkt-transition); font-weight: 600;
}
.kkt-search-btn:hover { transform: translateY(-1px); box-shadow: 0 4px 15px rgba(230,57,70,0.4); }

/* === Hero Banner === */
.kkt-hero {
  position: relative; height: 75vh; min-height: 500px;
  overflow: hidden; display: flex; align-items: center;
}
.kkt-hero-bg {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  object-fit: cover; opacity: 0.6;
}
.kkt-hero-overlay {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  background: linear-gradient(135deg, rgba(13,17,23,0.85) 0%, rgba(29,53,87,0.6) 50%, rgba(13,17,23,0.85) 100%);
}
.kkt-hero-content {
  position: relative; z-index: 2; max-width: 1280px; margin: 0 auto; padding: 0 20px;
}
.kkt-hero h1 { font-size: 3.2rem; margin-bottom: 16px; text-shadow: 0 2px 10px rgba(0,0,0,0.5); }
.kkt-hero h1 .kkt-brand { color: var(--kkt-red); }
.kkt-hero p { font-size: 1.2rem; color: var(--kkt-light-gray); max-width: 600px; margin-bottom: 32px; }
.kkt-hero-tags { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 32px; }
.kkt-hero-tag {
  background: rgba(230,57,70,0.15); border: 1px solid rgba(230,57,70,0.3);
  padding: 6px 16px; border-radius: 20px; font-size: 0.85rem; color: var(--kkt-red);
}
.kkt-hero-btns { display: flex; gap: 16px; flex-wrap: wrap; }
.kkt-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 32px; border-radius: 8px; font-weight: 600;
  font-size: 1rem; cursor: pointer; transition: var(--kkt-transition);
  border: none; text-decoration: none;
}
.kkt-btn-primary { background: var(--kkt-gradient-red); color: #fff; }
.kkt-btn-primary:hover { transform: translateY(-2px); box-shadow: var(--kkt-shadow-hover); color: #fff; }
.kkt-btn-outline {
  background: transparent; color: #fff;
  border: 2px solid rgba(255,255,255,0.3);
}
.kkt-btn-outline:hover { border-color: var(--kkt-amber); color: var(--kkt-amber); }

/* === Section Headers === */
.kkt-section-header { text-align: center; margin-bottom: 50px; }
.kkt-section-header h2 { font-size: 2.2rem; margin-bottom: 12px; }
.kkt-section-header h2 .kkt-brand { color: var(--kkt-red); }
.kkt-section-header p { color: var(--kkt-light-gray); font-size: 1.05rem; max-width: 650px; margin: 0 auto; }
.kkt-section-line {
  width: 60px; height: 3px; background: var(--kkt-gradient-red);
  margin: 16px auto 0; border-radius: 2px;
}

/* === Video Card Grid === */
.kkt-video-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}
.kkt-video-card {
  background: var(--kkt-card-bg); border-radius: var(--kkt-radius);
  overflow: hidden; border: 1px solid var(--kkt-border);
  transition: var(--kkt-transition); cursor: pointer;
}
.kkt-video-card:hover {
  transform: translateY(-6px); border-color: var(--kkt-red);
  box-shadow: var(--kkt-shadow-hover);
}
.kkt-video-thumb {
  position: relative; padding-top: 56.25%; overflow: hidden;
}
.kkt-video-thumb img {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  object-fit: cover; transition: transform 0.5s ease;
}
.kkt-video-card:hover .kkt-video-thumb img { transform: scale(1.05); }
.kkt-video-play {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);
  width: 60px; height: 60px; background: rgba(230,57,70,0.9);
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  opacity: 0; transition: var(--kkt-transition); z-index: 2;
}
.kkt-video-play::after {
  content: ''; width: 0; height: 0;
  border-style: solid; border-width: 10px 0 10px 18px;
  border-color: transparent transparent transparent #fff;
  margin-left: 3px;
}
.kkt-video-card:hover .kkt-video-play { opacity: 1; }
.kkt-video-duration {
  position: absolute; bottom: 8px; right: 8px;
  background: rgba(0,0,0,0.8); padding: 2px 8px;
  border-radius: 4px; font-size: 0.8rem; color: #fff; z-index: 2;
}
.kkt-video-info { padding: 16px; }
.kkt-video-title {
  font-size: 1rem; font-weight: 600; color: #fff;
  margin-bottom: 8px; display: -webkit-box;
  -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.kkt-video-meta {
  display: flex; align-items: center; gap: 16px;
  font-size: 0.85rem; color: var(--kkt-light-gray);
}
.kkt-video-meta span { display: flex; align-items: center; gap: 4px; }
.kkt-video-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.kkt-video-tag {
  background: rgba(244,162,97,0.1); color: var(--kkt-amber);
  padding: 2px 10px; border-radius: 12px; font-size: 0.75rem;
}

/* === Feature Cards === */
.kkt-feature-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}
.kkt-feature-card {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); padding: 32px 24px;
  text-align: center; transition: var(--kkt-transition);
}
.kkt-feature-card:hover {
  border-color: var(--kkt-red); transform: translateY(-4px);
  box-shadow: var(--kkt-shadow-hover);
}
.kkt-feature-icon {
  width: 64px; height: 64px; margin: 0 auto 20px;
  background: rgba(230,57,70,0.1); border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.8rem;
}
.kkt-feature-card h3 { font-size: 1.15rem; margin-bottom: 10px; }
.kkt-feature-card p { color: var(--kkt-light-gray); font-size: 0.9rem; }

/* === Expert Section === */
.kkt-expert-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}
.kkt-expert-card {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); overflow: hidden;
  transition: var(--kkt-transition); text-align: center; padding-bottom: 20px;
}
.kkt-expert-card:hover { border-color: var(--kkt-amber); transform: translateY(-4px); }
.kkt-expert-avatar {
  width: 120px; height: 120px; border-radius: 50%;
  margin: 24px auto 16px; overflow: hidden;
  border: 3px solid var(--kkt-red);
}
.kkt-expert-avatar img { width: 100%; height: 100%; object-fit: cover; }
.kkt-expert-card h3 { font-size: 1.1rem; margin-bottom: 4px; }
.kkt-expert-role { color: var(--kkt-amber); font-size: 0.85rem; margin-bottom: 12px; }
.kkt-expert-desc { color: var(--kkt-light-gray); font-size: 0.85rem; padding: 0 20px; margin-bottom: 16px; }

/* === FAQ Section === */
.kkt-faq-list { max-width: 800px; margin: 0 auto; }
.kkt-faq-item {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius-sm); margin-bottom: 12px; overflow: hidden;
}
.kkt-faq-q {
  padding: 18px 24px; cursor: pointer; display: flex;
  justify-content: space-between; align-items: center;
  font-weight: 600; color: #fff; transition: var(--kkt-transition);
}
.kkt-faq-q:hover { color: var(--kkt-red); }
.kkt-faq-q::after { content: '+'; font-size: 1.4rem; color: var(--kkt-red); transition: var(--kkt-transition); }
.kkt-faq-item.active .kkt-faq-q::after { content: '-'; }
.kkt-faq-a {
  max-height: 0; overflow: hidden; transition: max-height 0.4s ease;
  padding: 0 24px; color: var(--kkt-light-gray); font-size: 0.95rem;
}
.kkt-faq-item.active .kkt-faq-a { max-height: 300px; padding-bottom: 18px; }

/* === Reviews === */
.kkt-review-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}
.kkt-review-card {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); padding: 24px;
}
.kkt-review-stars { color: var(--kkt-amber); margin-bottom: 12px; font-size: 1.1rem; letter-spacing: 2px; }
.kkt-review-text { color: var(--kkt-light-gray); font-size: 0.95rem; margin-bottom: 16px; font-style: italic; }
.kkt-review-author { display: flex; align-items: center; gap: 12px; }
.kkt-review-avatar-placeholder {
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--kkt-gradient-red); display: flex;
  align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-size: 0.9rem;
}
.kkt-review-name { font-weight: 600; color: #fff; font-size: 0.9rem; }
.kkt-review-date { color: var(--kkt-light-gray); font-size: 0.8rem; }

/* === Brand Wall === */
.kkt-brand-wall { text-align: center; padding: 40px 0; }
.kkt-brand-wall img {
  max-width: 100%; border-radius: var(--kkt-radius);
  opacity: 0.8; transition: var(--kkt-transition);
}
.kkt-brand-wall img:hover { opacity: 1; }

/* === Contact Section === */
.kkt-contact-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}
.kkt-contact-card {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); padding: 28px; text-align: center;
}
.kkt-contact-card h3 { font-size: 1.1rem; margin-bottom: 16px; color: var(--kkt-amber); }
.kkt-contact-card p { color: var(--kkt-light-gray); font-size: 0.9rem; margin-bottom: 8px; text-align: left; }
.kkt-contact-card img { max-width: 180px; margin: 12px auto; border-radius: 8px; }

/* === How-To Guide === */
.kkt-howto-steps {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 24px; counter-reset: step;
}
.kkt-howto-step {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); padding: 28px; text-align: center;
  position: relative; counter-increment: step;
}
.kkt-howto-step::before {
  content: counter(step); position: absolute; top: -16px; left: 50%;
  transform: translateX(-50%); width: 32px; height: 32px;
  background: var(--kkt-gradient-red); border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.9rem; color: #fff;
}
.kkt-howto-step h4 { margin-top: 8px; margin-bottom: 10px; font-size: 1rem; }
.kkt-howto-step p { color: var(--kkt-light-gray); font-size: 0.85rem; }

/* === Share Buttons === */
.kkt-share { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.kkt-share-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 16px; border-radius: 6px; font-size: 0.85rem;
  border: 1px solid var(--kkt-border); color: var(--kkt-light-gray);
  background: var(--kkt-card-bg); cursor: pointer; transition: var(--kkt-transition);
}
.kkt-share-btn:hover { border-color: var(--kkt-red); color: #fff; }

/* === Footer === */
.kkt-footer {
  background: #080B10; border-top: 1px solid var(--kkt-border);
  padding: 60px 0 30px;
}
.kkt-footer-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 40px; margin-bottom: 40px;
}
.kkt-footer-col h4 { font-size: 1.05rem; margin-bottom: 16px; color: #fff; }
.kkt-footer-col p { color: var(--kkt-light-gray); font-size: 0.85rem; margin-bottom: 8px; }
.kkt-footer-col a { display: block; color: var(--kkt-light-gray); font-size: 0.85rem; margin-bottom: 8px; }
.kkt-footer-col a:hover { color: var(--kkt-red); }
.kkt-footer-col img { max-width: 140px; border-radius: 8px; margin-top: 8px; }
.kkt-footer-bottom {
  border-top: 1px solid var(--kkt-border); padding-top: 24px;
  text-align: center; color: var(--kkt-light-gray); font-size: 0.85rem;
}
.kkt-footer-bottom a { color: var(--kkt-amber); }

/* === Breadcrumb === */
.kkt-breadcrumb {
  padding: 16px 0; font-size: 0.85rem; color: var(--kkt-light-gray);
  margin-top: 70px;
}
.kkt-breadcrumb a { color: var(--kkt-amber); }
.kkt-breadcrumb span { margin: 0 8px; }

/* === Community Grid === */
.kkt-community-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}
.kkt-community-card {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius-sm); padding: 20px; text-align: center;
  transition: var(--kkt-transition);
}
.kkt-community-card:hover { border-color: var(--kkt-red); transform: translateY(-3px); }
.kkt-community-icon { font-size: 2rem; margin-bottom: 10px; }
.kkt-community-card h4 { font-size: 0.95rem; margin-bottom: 6px; }
.kkt-community-card p { color: var(--kkt-light-gray); font-size: 0.8rem; }

/* === AI Section === */
.kkt-ai-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 24px;
}
.kkt-ai-card {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); padding: 32px;
  position: relative; overflow: hidden; transition: var(--kkt-transition);
}
.kkt-ai-card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: var(--kkt-gradient-red);
}
.kkt-ai-card:hover { border-color: var(--kkt-red); transform: translateY(-4px); }
.kkt-ai-card h3 { font-size: 1.15rem; margin-bottom: 12px; }
.kkt-ai-card p { color: var(--kkt-light-gray); font-size: 0.9rem; }

/* === Stats Bar === */
.kkt-stats {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
  padding: 40px 0;
}
.kkt-stat { text-align: center; }
.kkt-stat-num { font-size: 2.5rem; font-weight: 800; color: var(--kkt-red); }
.kkt-stat-label { color: var(--kkt-light-gray); font-size: 0.9rem; margin-top: 4px; }

/* === Interference tags - hidden === */
.kkt-noise { position: absolute; width: 0; height: 0; overflow: hidden; opacity: 0; pointer-events: none; }

/* === Animation - visible by default, enhanced with JS === */
.kkt-fade-in {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.kkt-fade-in.js-hidden {
  opacity: 0;
  transform: translateY(30px);
}
.kkt-fade-in.js-hidden.visible {
  opacity: 1;
  transform: translateY(0);
}

/* === Page Content === */
.kkt-page-hero {
  padding: 120px 0 60px;
  background: var(--kkt-gradient-navy);
  text-align: center;
}
.kkt-page-hero h1 { font-size: 2.4rem; margin-bottom: 12px; }
.kkt-page-hero p { color: var(--kkt-light-gray); font-size: 1.05rem; max-width: 700px; margin: 0 auto; }

.kkt-content-section { padding: 60px 0; }
.kkt-content-section h2 { font-size: 1.8rem; margin-bottom: 24px; }
.kkt-content-section p { color: var(--kkt-light-gray); margin-bottom: 16px; line-height: 1.8; }

/* === MCP Frontend Mock === */
.kkt-mcp-widget {
  background: var(--kkt-card-bg); border: 1px solid var(--kkt-border);
  border-radius: var(--kkt-radius); padding: 20px; margin-top: 20px;
}
.kkt-mcp-widget h4 { font-size: 0.95rem; margin-bottom: 12px; color: var(--kkt-amber); }
.kkt-mcp-input {
  width: 100%; background: var(--kkt-dark); border: 1px solid var(--kkt-border);
  border-radius: 6px; padding: 10px; color: #fff; font-size: 0.9rem; outline: none;
}
.kkt-mcp-btn {
  margin-top: 10px; background: var(--kkt-gradient-red); border: none;
  border-radius: 6px; padding: 8px 20px; color: #fff; cursor: pointer;
  font-size: 0.85rem; transition: var(--kkt-transition);
}
.kkt-mcp-btn:hover { opacity: 0.9; }

/* === Responsive === */
@media (max-width: 1024px) {
  .kkt-hero h1 { font-size: 2.4rem; }
  .kkt-stats { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .kkt-nav { display: none; }
  .kkt-nav.active {
    display: flex; flex-direction: column; position: absolute;
    top: 70px; left: 0; right: 0; background: rgba(13,17,23,0.98);
    padding: 20px; border-bottom: 1px solid var(--kkt-border);
  }
  .kkt-mobile-toggle { display: block; }
  .kkt-hero { height: 60vh; min-height: 400px; }
  .kkt-hero h1 { font-size: 1.8rem; }
  .kkt-hero p { font-size: 1rem; }
  .kkt-section { padding: 50px 0; }
  .kkt-section-header h2 { font-size: 1.6rem; }
  .kkt-video-grid { grid-template-columns: 1fr; }
  .kkt-feature-grid { grid-template-columns: 1fr; }
  .kkt-expert-grid { grid-template-columns: 1fr; }
  .kkt-ai-grid { grid-template-columns: 1fr; }
  .kkt-stats { grid-template-columns: repeat(2, 1fr); gap: 16px; }
  .kkt-stat-num { font-size: 1.8rem; }
  .kkt-footer-grid { grid-template-columns: 1fr 1fr; }
  .kkt-search-inner { flex-direction: column; }
  .kkt-search-btn { width: 100%; text-align: center; justify-content: center; }
}

@media (max-width: 480px) {
  .kkt-hero h1 { font-size: 1.5rem; }
  .kkt-hero-btns { flex-direction: column; }
  .kkt-btn { width: 100%; justify-content: center; }
  .kkt-footer-grid { grid-template-columns: 1fr; }
  .kkt-community-grid { grid-template-columns: 1fr 1fr; }
}