/* roulang page: index */
:root {
      --primary: #2C6FCE;
      --accent: #E8553D;
      --bg-white: #FFFFFF;
      --bg-light: #F7F9FC;
      --text-dark: #1A1A1A;
      --text-muted: #5A5A5A;
      --border-light: #E8ECF1;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --shadow-card: 0 2px 12px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 24px rgba(0,0,0,0.10);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
      --nav-width: 260px;
      --transition: 0.3s ease;
    }
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-white);
      color: var(--text-dark);
      line-height: 1.7;
      font-size: 16px;
      display: flex;
      flex-direction: row;
      min-height: 100vh;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    button, input, textarea {
      font-family: inherit;
    }
    .app-nav {
      position: fixed;
      top: 0;
      left: 0;
      width: var(--nav-width);
      height: 100vh;
      background-color: #FBFCFD;
      border-right: 1px solid var(--border-light);
      display: flex;
      flex-direction: column;
      padding: 32px 24px;
      z-index: 40;
      overflow-y: auto;
    }
    .nav-logo {
      margin-bottom: 48px;
    }
    .nav-logo .brand {
      font-size: 28px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 1px;
      display: block;
      line-height: 1.2;
    }
    .nav-logo .domain {
      font-size: 12px;
      color: var(--text-muted);
      letter-spacing: 0.3px;
      margin-top: 2px;
    }
    .nav-menu {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 28px;
    }
    .nav-menu li a {
      display: block;
      font-size: 16px;
      font-weight: 500;
      color: var(--text-muted);
      padding: 4px 0;
      position: relative;
      transition: color var(--transition), transform var(--transition);
      border-left: 3px solid transparent;
      padding-left: 12px;
    }
    .nav-menu li a:hover {
      color: var(--primary);
      transform: translateX(4px);
    }
    .nav-menu li a.active {
      color: var(--primary);
      border-left-color: var(--accent);
      font-weight: 600;
    }
    .mobile-header {
      display: none;
    }
    .main-content {
      margin-left: var(--nav-width);
      width: calc(100% - var(--nav-width));
      background: var(--bg-white);
    }
    .section {
      padding: 100px 48px;
      max-width: 1200px;
      margin: 0 auto;
    }
    .section-alt {
      background-color: var(--bg-light);
    }
    h1 {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.3;
      margin-bottom: 20px;
      color: var(--text-dark);
    }
    h2 {
      font-size: 36px;
      font-weight: 600;
      line-height: 1.4;
      margin-bottom: 48px;
      color: var(--text-dark);
    }
    h3 {
      font-size: 22px;
      font-weight: 600;
      margin-bottom: 12px;
    }
    .btn {
      display: inline-block;
      font-weight: 600;
      font-size: 16px;
      letter-spacing: 0.5px;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      transition: background var(--transition), border var(--transition), color var(--transition);
      cursor: pointer;
      text-align: center;
    }
    .btn-primary {
      background: var(--accent);
      color: white;
      border: none;
    }
    .btn-primary:hover {
      background: #D1442F;
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
    }
    .btn-outline:hover {
      background: rgba(44,111,206,0.05);
    }
    .hero-grid {
      display: flex;
      gap: 60px;
      align-items: center;
    }
    .hero-left {
      flex: 0 0 55%;
    }
    .hero-right {
      flex: 0 0 45%;
    }
    .hero-right img {
      border-radius: 16px;
      box-shadow: 0 4px 20px rgba(0,0,0,0.08);
      width: 100%;
      height: auto;
      object-fit: cover;
    }
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
    }
    .adv-card {
      background: white;
      padding: 32px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: transform var(--transition), box-shadow var(--transition);
      border: none;
    }
    .adv-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .icon-css {
      width: 48px;
      height: 48px;
      margin-bottom: 20px;
      position: relative;
    }
    .icon-shield {
      border: 3px solid var(--primary);
      border-radius: 8px 8px 4px 4px;
      width: 36px;
      height: 42px;
      position: relative;
    }
    .icon-shield::after {
      content: '';
      position: absolute;
      bottom: -6px;
      left: 50%;
      transform: translateX(-50%);
      width: 12px;
      height: 6px;
      background: var(--primary);
      border-radius: 0 0 4px 4px;
    }
    .icon-lightning {
      width: 10px;
      height: 38px;
      background: var(--accent);
      transform: rotate(15deg);
      border-radius: 4px;
      margin-left: 12px;
    }
    .icon-lightning::before {
      content: '';
      position: absolute;
      top: -8px;
      left: -2px;
      width: 14px;
      height: 14px;
      background: var(--accent);
      border-radius: 2px;
      transform: rotate(45deg);
    }
    .icon-trophy {
      width: 30px;
      height: 36px;
      border: 3px solid var(--primary);
      border-radius: 50% 50% 6px 6px;
      position: relative;
    }
    .icon-trophy::after {
      content: '';
      position: absolute;
      bottom: -10px;
      left: 50%;
      transform: translateX(-50%);
      width: 8px;
      height: 10px;
      background: var(--primary);
    }
    .icon-signal {
      width: 8px;
      height: 28px;
      background: var(--primary);
      border-radius: 4px;
      box-shadow: 12px 8px 0 var(--primary), 24px 2px 0 var(--primary);
    }
    .icon-gear {
      width: 34px;
      height: 34px;
      border: 4px solid var(--primary);
      border-radius: 50%;
      position: relative;
    }
    .icon-gear::before {
      content: '';
      position: absolute;
      top: 4px;
      left: 12px;
      width: 6px;
      height: 26px;
      background: var(--primary);
    }
    .icon-flame {
      width: 24px;
      height: 30px;
      background: var(--accent);
      border-radius: 50% 50% 6px 6px;
      transform: rotate(10deg);
    }
    .cases-masonry {
      display: flex;
      gap: 32px;
    }
    .cases-left {
      flex: 0 0 55%;
      display: flex;
      flex-direction: column;
      gap: 32px;
    }
    .cases-right {
      flex: 0 0 45%;
      display: flex;
      flex-direction: column;
      gap: 32px;
      margin-top: 60px;
    }
    .case-card {
      background: white;
      border-radius: 12px;
      box-shadow: var(--shadow-card);
      overflow: hidden;
      transition: transform var(--transition);
    }
    .case-card:hover {
      transform: translateY(-2px);
      box-shadow: var(--shadow-hover);
    }
    .case-card img {
      width: 100%;
      height: 240px;
      object-fit: cover;
      transition: filter 0.3s ease, transform 0.3s ease;
    }
    .case-card:hover img {
      filter: saturate(1.1);
      transform: scale(1.02);
    }
    .case-text {
      padding: 20px 24px;
    }
    .tag {
      display: inline-block;
      background: #f0f4ff;
      color: var(--primary);
      font-size: 13px;
      padding: 4px 10px;
      border-radius: 20px;
      margin-right: 8px;
      margin-bottom: 8px;
    }
    .solutions-row {
      display: flex;
      gap: 28px;
    }
    .solution-col {
      flex: 1;
      background: white;
      border-radius: var(--radius-card);
      padding: 32px;
      border: 1px solid var(--border-light);
      box-shadow: var(--shadow-card);
    }
    .solution-col.featured {
      border: 2px solid var(--primary);
      box-shadow: var(--shadow-hover);
      position: relative;
    }
    .badge-popular {
      position: absolute;
      top: -12px;
      right: 20px;
      background: var(--accent);
      color: white;
      padding: 6px 16px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 600;
    }
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      background: white;
      padding: 20px 24px;
      font-weight: 700;
      font-size: 18px;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      transition: background 0.2s;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      background: #F7F9FC;
      padding: 0 24px;
      font-size: 15px;
    }
    .faq-item.active .faq-answer {
      max-height: 220px;
      padding: 16px 24px;
    }
    .faq-icon {
      font-size: 24px;
      transition: transform 0.3s;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    .contact-wrapper {
      display: flex;
      gap: 60px;
      align-items: flex-start;
    }
    .contact-left {
      flex: 1;
    }
    .contact-right {
      flex: 1;
    }
    .input-field {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-input);
      margin-bottom: 16px;
      transition: border 0.2s, box-shadow 0.2s;
    }
    .input-field:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(44,111,206,0.1);
    }
    .footer {
      background: #2c3e50;
      color: white;
      padding: 48px 48px 28px;
    }
    .footer-grid {
      display: flex;
      gap: 40px;
      max-width: 1200px;
      margin: 0 auto;
    }
    .footer-col {
      flex: 1;
    }
    .footer-links a {
      display: block;
      color: #B0BEC5;
      margin-bottom: 10px;
      transition: color var(--transition);
    }
    .footer-links a:hover {
      color: var(--accent);
    }
    @media (max-width: 1024px) {
      .app-nav {
        display: none;
      }
      .main-content {
        margin-left: 0;
        width: 100%;
      }
      .mobile-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 16px 24px;
        background: white;
        border-bottom: 1px solid var(--border-light);
        position: sticky;
        top: 0;
        z-index: 50;
      }
      .hero-grid {
        flex-direction: column;
      }
      .advantages-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .cases-masonry {
        flex-direction: column;
      }
      .solutions-row {
        flex-direction: column;
      }
      .footer-grid {
        flex-direction: column;
      }
    }
    @media (max-width: 768px) {
      .advantages-grid {
        grid-template-columns: 1fr;
      }
      .section {
        padding: 64px 24px;
      }
    }