/* roulang page: index */
:root {
      --red: #E43D30;
      --red-hover: #C42D1F;
      --black: #0D0F13;
      --black-light: #1A1D23;
      --orange: #FF6B35;
      --green-accent: #00A86B;
      --gray-bg: #F2F3F5;
      --gray-mid: #6B7280;
      --white: #FFFFFF;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 6px;
      --shadow-card: 0 4px 20px rgba(13,15,19,0.08);
      --shadow-card-hover: 0 8px 30px rgba(13,15,19,0.15);
      --transition: all 0.25s ease;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-number: "Inter", "Roboto", sans-serif;
      --max-width: 1200px;
      --header-height: 70px;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--white);
      color: #1F2937;
      line-height: 1.5;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      padding-top: var(--header-height);
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-weight: 600;
      transition: var(--transition);
    }

    .container {
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 导航栏 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: rgba(13, 15, 19, 0.95);
      backdrop-filter: blur(8px);
      z-index: 100;
      display: flex;
      align-items: center;
      border-bottom: 1px solid transparent;
      transition: var(--transition);
    }

    .site-header.scrolled {
      border-bottom: 1px solid var(--red);
      box-shadow: 0 2px 12px rgba(0,0,0,0.3);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    .logo {
      font-size: 1.8rem;
      font-weight: 800;
      color: var(--white);
      letter-spacing: 1px;
      display: flex;
      align-items: center;
      gap: 4px;
      white-space: nowrap;
    }
    .logo span {
      color: var(--red);
    }

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

    .nav-links a {
      color: #E5E7EB;
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      padding: 4px 0;
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: var(--white);
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--red);
      transition: width 0.2s;
    }

    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }

    .btn-nav {
      background: var(--red);
      color: white;
      padding: 10px 22px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      font-size: 0.9rem;
      box-shadow: 0 2px 8px rgba(228,61,48,0.4);
      white-space: nowrap;
    }
    .btn-nav:hover {
      background: var(--red-hover);
      box-shadow: 0 4px 12px rgba(228,61,48,0.6);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
    }
    .hamburger span {
      width: 26px;
      height: 3px;
      background: var(--white);
      border-radius: 4px;
      transition: 0.3s;
    }

    .mobile-menu {
      display: none;
      position: fixed;
      top: var(--header-height);
      left: 0;
      width: 100%;
      background: rgba(13,15,19,0.98);
      backdrop-filter: blur(12px);
      padding: 24px;
      flex-direction: column;
      gap: 20px;
      z-index: 90;
    }
    .mobile-menu a {
      color: #E5E7EB;
      font-size: 1.2rem;
      font-weight: 500;
      padding: 8px 0;
      border-bottom: 1px solid #2D2F34;
    }
    .mobile-menu .btn-nav {
      width: fit-content;
      margin-top: 10px;
    }

    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .mobile-menu.active { display: flex; }
    }

    /* Hero */
    .hero {
      background: linear-gradient(135deg, #0D0F13 0%, #E43D30 100%);
      position: relative;
      overflow: hidden;
      padding: 80px 0;
    }
    .hero::before {
      content: "";
      position: absolute;
      inset: 0;
      background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 100" opacity="0.08"><path d="M0 20 Q25 10 50 20 T100 20 T150 20 T200 20" stroke="white" fill="none" stroke-width="1.5"/><path d="M0 60 Q25 70 50 60 T100 60 T150 60 T200 60" stroke="white" fill="none"/></svg>');
      background-size: cover;
    }
    .hero .container {
      display: flex;
      align-items: center;
      gap: 40px;
      position: relative;
      z-index: 2;
    }
    .hero-text {
      flex: 1;
      color: white;
    }
    .hero h1 {
      font-size: 48px;
      font-weight: 900;
      line-height: 1.2;
      margin-bottom: 24px;
    }
    .hero .subtitle {
      font-size: 18px;
      opacity: 0.9;
      margin-bottom: 32px;
      max-width: 500px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--red);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      box-shadow: 0 4px 14px rgba(228,61,48,0.5);
    }
    .btn-primary:hover {
      background: var(--red-hover);
      box-shadow: 0 0 0 2px rgba(255,255,255,0.3), 0 6px 20px rgba(228,61,48,0.7);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid white;
      color: white;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: white;
      color: var(--black);
    }
    .hero-mockup {
      flex: 1;
      display: flex;
      justify-content: center;
    }
    .hero-mockup img {
      max-height: 420px;
      border-radius: 24px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.5);
    }
    @media (max-width: 768px) {
      .hero .container {
        flex-direction: column;
        text-align: center;
      }
      .hero h1 { font-size: 32px; }
      .hero-buttons { justify-content: center; }
      .hero-mockup img { max-height: 280px; }
    }

    section {
      padding: 80px 0;
    }
    .section-title {
      font-size: 36px;
      font-weight: 800;
      margin-bottom: 16px;
      text-align: center;
    }
    .section-desc {
      color: var(--gray-mid);
      text-align: center;
      max-width: 600px;
      margin: 0 auto 48px;
    }

    /* 核心优势 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--gray-bg);
      padding: 28px 20px;
      border-radius: var(--radius-card);
      text-align: center;
      transition: var(--transition);
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }
    .feature-icon {
      font-size: 2.2rem;
      color: var(--orange);
      margin-bottom: 16px;
    }
    .feature-card h3 {
      font-size: 20px;
      font-weight: 700;
      margin-bottom: 8px;
    }

    /* 服务矩阵 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3,1fr);
      gap: 24px;
    }
    .service-card {
      background: white;
      border: 1px solid #E5E7EB;
      border-radius: var(--radius-card);
      overflow: hidden;
      transition: var(--transition);
    }
    .service-card:hover {
      box-shadow: var(--shadow-card);
      border-color: #ccc;
    }
    .service-img {
      width: 100%;
      aspect-ratio: 16/9;
      object-fit: cover;
    }
    .service-content {
      padding: 20px;
    }
    .tags {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      margin-top: 14px;
    }
    .tag {
      background: var(--orange);
      color: white;
      padding: 4px 12px;
      border-radius: var(--radius-tag);
      font-size: 0.8rem;
      font-weight: 600;
    }

    /* 数据 */
    .stats-band {
      background: var(--gray-bg);
    }
    .stats-grid {
      display: flex;
      justify-content: space-around;
      text-align: center;
      flex-wrap: wrap;
    }
    .stat-number {
      font-family: var(--font-number);
      font-size: 48px;
      font-weight: 800;
      color: var(--red);
    }
    .stat-label {
      color: var(--gray-mid);
      font-weight: 500;
    }

    /* CTA */
    .cta-dark {
      background: var(--black);
      text-align: center;
      color: white;
    }
    .download-buttons {
      display: flex;
      justify-content: center;
      gap: 20px;
      flex-wrap: wrap;
      margin: 32px 0;
    }
    .btn-store {
      background: #1A1D23;
      color: white;
      padding: 14px 30px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      display: flex;
      align-items: center;
      gap: 10px;
    }
    .btn-store:hover {
      border: 1px solid var(--red);
      background: #262A31;
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid #E5E7EB;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 20px 0;
      font-weight: 600;
      font-size: 18px;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--gray-mid);
      padding-left: 4px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 16px;
    }
    .faq-item.active .faq-question {
      color: var(--red);
    }

    footer {
      background: var(--black);
      color: #D1D5DB;
      padding: 60px 0 24px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 30px;
    }
    @media (max-width: 768px) {
      .features-grid { grid-template-columns: repeat(2,1fr); }
      .services-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
    }