/* roulang page: index */
:root {
      --primary-deep: #0B0C10;
      --primary-dark: #1A1A2E;
      --accent-gold: #F0A500;
      --accent-cyan: #00B4D8;
      --bg-light: #FAFAFA;
      --text-dark: #1A1A1A;
      --text-muted: #555555;
      --text-light: #CCCCCC;
      --white: #FFFFFF;
      --border-light: #EEEEEE;
      --card-shadow: 0 4px 20px rgba(0,0,0,0.06);
      --card-shadow-hover: 0 8px 30px rgba(0,0,0,0.12);
      --radius-card: 12px;
      --radius-btn: 8px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --nav-width: 230px;
      --transition: 0.3s ease;
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-light);
      color: var(--text-dark);
      line-height: 1.7;
      font-size: 16px;
      display: flex;
      flex-direction: column;
      min-height: 100vh;
      -webkit-font-smoothing: antialiased;
    }

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

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

    button, .button {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      transition: all var(--transition);
    }

    h1, h2, h3 {
      font-weight: 600;
      line-height: 1.3;
    }

    h1 { font-size: 2.8rem; font-weight: 700; line-height: 1.2; }
    h2 { font-size: 2rem; }
    h3 { font-size: 1.4rem; }

    .container-main {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }

    /* 左侧竖向导航 (桌面) */
    .side-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: var(--nav-width);
      height: 100vh;
      background: linear-gradient(180deg, var(--primary-deep) 0%, var(--primary-dark) 100%);
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      padding: 2rem 1.2rem;
      z-index: 100;
      box-shadow: 4px 0 20px rgba(0,0,0,0.2);
    }

    .logo-area {
      margin-bottom: 3rem;
    }

    .logo-text {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--white);
      letter-spacing: 2px;
      display: block;
    }
    .logo-text span {
      color: var(--accent-gold);
    }

    .nav-links {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 1.5rem;
    }

    .nav-links li a {
      color: var(--text-light);
      font-size: 1rem;
      font-weight: 500;
      padding: 0.5rem 0;
      display: block;
      position: relative;
      transition: color 0.2s;
      letter-spacing: 0.5px;
    }

    .nav-links li a::before {
      content: '';
      position: absolute;
      left: -12px;
      top: 50%;
      transform: translateY(-50%);
      width: 4px;
      height: 18px;
      background-color: var(--accent-gold);
      border-radius: 4px;
      opacity: 0;
      transition: opacity 0.2s;
    }

    .nav-links li a:hover,
    .nav-links li a.active {
      color: var(--accent-gold);
    }
    .nav-links li a:hover::before,
    .nav-links li a.active::before {
      opacity: 1;
    }

    .nav-footer {
      margin-top: auto;
      color: var(--text-light);
      font-size: 0.8rem;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    /* 移动端顶部导航 */
    .mobile-header {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 60px;
      background: var(--primary-deep);
      z-index: 99;
      align-items: center;
      justify-content: space-between;
      padding: 0 20px;
      box-shadow: 0 2px 10px rgba(0,0,0,0.3);
    }
    .mobile-logo {
      font-size: 1.6rem;
      font-weight: 700;
      color: var(--white);
    }
    .mobile-logo span { color: var(--accent-gold); }
    .hamburger {
      color: var(--white);
      font-size: 1.8rem;
      background: none;
      border: none;
    }
    .mobile-menu {
      position: fixed;
      top: 60px;
      left: 0;
      width: 100%;
      background: to bottom, var(--primary-deep), var(--primary-dark);
      background: var(--primary-dark);
      flex-direction: column;
      padding: 1.5rem;
      display: none;
      z-index: 98;
      border-bottom: 2px solid var(--accent-gold);
    }
    .mobile-menu.open {
      display: flex;
    }
    .mobile-menu a {
      color: var(--text-light);
      padding: 0.8rem 0;
      border-bottom: 1px solid rgba(255,255,255,0.1);
      font-size: 1rem;
    }

    /* 主内容区偏移 */
    .main-content {
      margin-left: var(--nav-width);
      width: calc(100% - var(--nav-width));
      background: var(--bg-light);
    }

    section {
      padding: 90px 0;
    }

    .bg-dark-section {
      background: linear-gradient(135deg, #0B0C10 0%, #1A1A2E 100%);
      color: var(--white);
    }

    .btn-primary {
      background: var(--accent-gold);
      color: var(--primary-deep);
      font-weight: 600;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      display: inline-block;
      text-align: center;
      letter-spacing: 0.5px;
    }
    .btn-primary:hover {
      background: #D48E00;
      transform: scale(1.03);
      color: var(--primary-deep);
    }
    .btn-secondary {
      border: 2px solid var(--accent-gold);
      color: var(--accent-gold);
      background: transparent;
      padding: 10px 26px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-secondary:hover {
      background: var(--accent-gold);
      color: var(--primary-deep);
    }

    .card {
      background: var(--white);
      border-radius: var(--radius-card);
      box-shadow: var(--card-shadow);
      border: 1px solid var(--border-light);
      transition: all var(--transition);
      overflow: hidden;
    }
    .card:hover {
      box-shadow: var(--card-shadow-hover);
      transform: translateY(-2px);
    }

    .highlight-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 28px;
    }
    .highlight-card.large {
      grid-row: span 2;
    }

    .cases-waterfall {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 24px;
    }
    .case-card img {
      height: 200px;
      object-fit: cover;
      transition: transform 0.4s ease;
    }
    .case-card:hover img {
      transform: scale(1.05);
    }

    .comparison-table {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }
    .comp-col {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: 2rem 1.5rem;
      border: 2px solid transparent;
    }
    .comp-col.recommended {
      border-color: var(--accent-gold);
      background: #FFF9F0;
    }

    .process-steps {
      display: flex;
      justify-content: space-between;
      position: relative;
    }
    .step-item {
      text-align: center;
      flex:1;
      position: relative;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      padding: 16px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #F9F9F9;
      padding: 0 16px;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding: 16px;
    }

    footer {
      background: var(--primary-deep);
      color: var(--text-light);
      padding: 60px 0 30px;
    }

    @media (max-width: 1024px) {
      .cases-waterfall { grid-template-columns: 1fr 1fr; }
      .comparison-table { grid-template-columns: 1fr; }
    }

    @media (max-width: 768px) {
      .side-nav { display: none; }
      .mobile-header { display: flex; }
      .main-content { margin-left: 0; width: 100%; }
      h1 { font-size: 2.2rem; }
      section { padding: 60px 0; }
      .highlight-grid { grid-template-columns: 1fr; }
      .cases-waterfall { grid-template-columns: 1fr; }
      .process-steps { flex-direction: column; gap: 30px; }
      .hero-inner { flex-direction: column; }
      .hero-text { order: 2; }
      .hero-image { order: 1; height: 40vh; }
    }