/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --pp-primary: #0A66FF;
      --pp-accent: #00E5FF;
      --pp-energy: #FF4D2E;
      --pp-bg-deep: #080C14;
      --pp-surface: rgba(12, 26, 48, 0.7);
      --pp-border-light: rgba(255, 255, 255, 0.08);
      --pp-text-white: #FFFFFF;
      --pp-text-body: #B0C4DE;
      --pp-text-muted: #6A7F9B;
      --pp-radius-card: 16px;
      --pp-radius-btn: 30px;
      --pp-shadow-card: 0 8px 32px rgba(0, 0, 0, 0.4);
      --pp-shadow-glow: 0 0 20px rgba(0, 229, 255, 0.5);
      --pp-font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', system-ui, -apple-system, sans-serif;
      --pp-transition: 0.3s cubic-bezier(0.25, 0.8, 0.25, 1.2);
      --pp-container-max: 1280px;
    }

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

    body {
      font-family: var(--pp-font-sans);
      background-color: var(--pp-bg-deep);
      color: var(--pp-text-body);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      background-image: radial-gradient(circle at 20% 20%, rgba(10, 102, 255, 0.08) 0%, transparent 35%),
                        radial-gradient(circle at 80% 60%, rgba(0, 229, 255, 0.05) 0%, transparent 40%);
      background-attachment: fixed;
    }

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

    /* ----- 排版重置 ----- */
    h1, h2, h3, h4 {
      color: var(--pp-text-white);
      font-weight: 700;
      line-height: 1.3;
    }
    h1 { font-size: 48px; letter-spacing: -0.5px; }
    h2 { font-size: 36px; }
    h3 { font-size: 24px; font-weight: 600; }
    h4 { font-size: 20px; font-weight: 600; }
    p { margin-bottom: 1rem; }
    a { text-decoration: none; color: inherit; }
    img { max-width: 100%; display: block; }

    /* ----- 导航组件 (沉浸式) ----- */
    .header {
      position: sticky;
      top: 0;
      z-index: 50;
      padding: 16px 0;
      transition: background 0.4s, backdrop-filter 0.4s;
      background: transparent;
    }
    .header.scrolled {
      background: rgba(8, 12, 20, 0.85);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      box-shadow: 0 4px 20px rgba(0,0,0,0.3);
    }
    .nav {
      display: flex;
      align-items: center;
      justify-content: space-between;
      max-width: var(--pp-container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-size: 28px;
      font-weight: 700;
      color: var(--pp-text-white);
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--pp-primary);
      font-size: 32px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-weight: 500;
      font-size: 15px;
      color: var(--pp-text-body);
      position: relative;
      padding: 8px 0;
      transition: color 0.3s;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--pp-accent);
    }
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--pp-accent);
      box-shadow: 0 0 12px var(--pp-accent);
    }
    .btn-nav {
      background: var(--pp-primary);
      color: white;
      padding: 10px 24px;
      border-radius: var(--pp-radius-btn);
      font-weight: 600;
      transition: var(--pp-transition);
      border: none;
      cursor: pointer;
    }
    .btn-nav:hover {
      background: linear-gradient(135deg, var(--pp-primary), var(--pp-accent));
      box-shadow: var(--pp-shadow-glow);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      cursor: pointer;
      gap: 5px;
    }
    .hamburger span {
      width: 28px;
      height: 3px;
      background: white;
      transition: 0.3s;
      border-radius: 3px;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(8, 12, 20, 0.96);
      backdrop-filter: blur(24px);
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 40px;
      z-index: 45;
      opacity: 0;
      transform: translateY(-20px);
      transition: 0.4s ease;
    }
    .mobile-menu.active {
      display: flex;
      opacity: 1;
      transform: translateY(0);
    }
    .mobile-menu a {
      font-size: 28px;
      font-weight: 600;
      color: var(--pp-text-white);
    }

    /* ----- 按钮系统 ----- */
    .btn-primary {
      background: var(--pp-primary);
      color: white;
      padding: 14px 32px;
      border-radius: var(--pp-radius-btn);
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: var(--pp-transition);
      border: none;
      cursor: pointer;
      box-shadow: 0 4px 12px rgba(10,102,255,0.3);
    }
    .btn-primary:hover {
      background: linear-gradient(135deg, var(--pp-primary), var(--pp-accent));
      box-shadow: var(--pp-shadow-glow);
      transform: translateY(-2px);
    }
    .btn-ghost {
      background: transparent;
      border: 2px solid var(--pp-primary);
      color: var(--pp-primary);
      padding: 12px 30px;
      border-radius: var(--pp-radius-btn);
      font-weight: 600;
      transition: var(--pp-transition);
      cursor: pointer;
    }
    .btn-ghost:hover {
      background: var(--pp-primary);
      color: white;
      box-shadow: 0 0 18px rgba(10,102,255,0.6);
    }
    .btn-energy {
      background: var(--pp-energy);
      color: white;
      border: none;
    }
    .btn-energy:hover {
      background: #ff3617;
      box-shadow: 0 0 24px rgba(255,77,46,0.6);
    }

    /* ----- 卡片玻璃拟态 ----- */
    .glass-card {
      background: var(--pp-surface);
      backdrop-filter: blur(18px);
      -webkit-backdrop-filter: blur(18px);
      border: 1px solid var(--pp-border-light);
      border-radius: var(--pp-radius-card);
      box-shadow: var(--pp-shadow-card);
      transition: all 0.3s ease;
    }
    .glass-card:hover {
      box-shadow: 0 16px 48px rgba(0, 166, 255, 0.15);
      transform: translateY(-6px);
    }

    /* ----- 区块间距 ----- */
    section {
      padding: 100px 0;
    }

    /* ----- Hero 区域 ----- */
    .hero {
      display: flex;
      align-items: center;
      min-height: 90vh;
      position: relative;
      overflow: hidden;
    }
    .hero-content {
      max-width: 600px;
      z-index: 2;
    }
    .hero h1 {
      margin-bottom: 20px;
    }
    .hero .subtitle {
      font-size: 20px;
      color: var(--pp-text-body);
      margin-bottom: 40px;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .hero-visual {
      position: absolute;
      right: 0;
      top: 0;
      width: 50%;
      height: 100%;
      background: radial-gradient(circle at 30% 40%, rgba(0,229,255,0.15) 0%, transparent 50%),
                  repeating-linear-gradient(45deg, rgba(255,255,255,0.02) 0px, rgba(255,255,255,0.02) 2px, transparent 2px, transparent 8px);
      z-index: 0;
      pointer-events: none;
    }

    /* 服务卡片网格 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 2.5rem;
    }
    .service-card {
      padding: 32px;
      text-align: left;
      position: relative;
      overflow: hidden;
    }
    .service-icon {
      font-size: 40px;
      color: var(--pp-accent);
      margin-bottom: 24px;
    }
    .service-card h3 {
      margin-bottom: 12px;
    }
    .indicator {
      width: 40px;
      height: 4px;
      background: var(--pp-primary);
      margin-top: 20px;
      border-radius: 4px;
      transition: width 0.3s;
    }
    .service-card:hover .indicator {
      width: 70px;
      background: var(--pp-accent);
    }

    /* 数据区块 */
    .data-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 2rem;
      text-align: center;
    }
    .data-item .number {
      font-size: 48px;
      font-weight: 700;
      font-family: 'Inter', sans-serif;
      color: var(--pp-text-white);
      line-height: 1.2;
    }
    .data-item .unit {
      font-size: 20px;
      color: var(--pp-accent);
      margin-left: 4px;
    }
    .data-item .label {
      color: var(--pp-text-muted);
      font-size: 15px;
      margin-top: 8px;
    }

    /* 案例网格 */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 2rem;
    }
    .case-card {
      padding: 28px;
      display: flex;
      flex-direction: column;
    }
    .case-img {
      width: 100%;
      height: 140px;
      background: #1a2330;
      border-radius: 12px;
      margin-bottom: 20px;
      object-fit: cover;
    }
    .case-card h4 {
      margin-bottom: 8px;
    }

    /* 解决方案交替 */
    .solution-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }
    .solution-row.reverse {
      flex-direction: row-reverse;
    }
    .solution-text {
      flex: 1;
    }
    .solution-img {
      flex: 1;
      border-radius: 20px;
      overflow: hidden;
      box-shadow: 0 20px 40px rgba(0,0,0,0.5);
    }
    .solution-img img {
      width: 100%;
      height: auto;
      object-fit: cover;
    }
    .check-list {
      list-style: none;
      margin-top: 20px;
    }
    .check-list li {
      display: flex;
      align-items: center;
      gap: 10px;
      margin-bottom: 12px;
      color: var(--pp-text-body);
    }
    .check-list i {
      color: var(--pp-accent);
      font-size: 18px;
    }

    /* FAQ */
    .faq-container {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid rgba(255,255,255,0.1);
      margin-bottom: 12px;
    }
    .faq-question {
      width: 100%;
      background: transparent;
      border: none;
      padding: 20px 0;
      font-size: 18px;
      font-weight: 600;
      color: var(--pp-text-white);
      display: flex;
      justify-content: space-between;
      cursor: pointer;
      text-align: left;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.4s;
      color: var(--pp-text-body);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 20px;
    }
    .faq-item.active .faq-question i {
      transform: rotate(180deg);
    }

    /* CTA 横幅 */
    .cta-banner {
      background: rgba(12, 26, 48, 0.5);
      backdrop-filter: blur(16px);
      border-radius: 24px;
      padding: 60px 40px;
      text-align: center;
      margin-top: 40px;
    }

    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      padding: 60px 0 30px;
    }
    .footer-col h4 {
      margin-bottom: 20px;
      color: white;
    }
    .footer-col a {
      display: block;
      color: var(--pp-text-muted);
      margin-bottom: 10px;
      transition: color 0.2s;
    }
    .footer-col a:hover {
      color: var(--pp-accent);
    }
    .copyright {
      border-top: 1px solid rgba(255,255,255,0.08);
      padding: 24px 0;
      text-align: center;
      color: var(--pp-text-muted);
      font-size: 14px;
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      h1 { font-size: 40px; }
      .services-grid { grid-template-columns: repeat(2, 1fr); }
      .data-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 768px) {
      .nav-links, .btn-nav { display: none; }
      .hamburger { display: flex; }
      section { padding: 70px 0; }
      .hero { flex-direction: column; text-align: center; padding-top: 80px; }
      .hero-visual { position: relative; width: 100%; height: 300px; margin-top: 30px; }
      .services-grid, .cases-grid, .data-grid { grid-template-columns: 1fr; }
      .solution-row, .solution-row.reverse { flex-direction: column; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 520px) {
      .footer-grid { grid-template-columns: 1fr; }
      .hero-buttons { flex-direction: column; align-items: center; }
    }