:root {
      --primary-color: #2563eb;
      --primary-hover: #1d4ed8;
      --bg-light: #f9fafb;
      --text-dark: #1f2937;
      --text-gray: #6b7280;
      --card-shadow: 0 6px 16px rgba(0, 0, 0, 0.06);
      --transition: all 0.2s ease;
    }

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

    body {
      font-family: 'Inter', system-ui, -apple-system, sans-serif;
      color: var(--text-dark);
      background-color: var(--bg-light);
      line-height: 1.6;
      padding-top: 76px;
    }

    /* ===== Navbar ===== */
    .navbar {
      background-color: #fff !important;
      box-shadow: var(--card-shadow);
      padding: 0.6rem 0;
    }

    .logo-container {
      display: inline-flex;
      align-items: center;
      gap: 0.75rem;
      text-decoration: none;
      user-select: none;
    }

    .logo-img {
      height: 46px;
      width: auto;
      object-fit: contain;
      border-radius: 10px;
      display: block;
    }

    /* 手机端显示品牌文字（更清晰），桌面默认隐藏 */
    .brand-text {
      font-weight: 900;
      font-size: 1.05rem;
      color: var(--text-dark);
      display: none;
      letter-spacing: 0.2px;
    }

    .nav-link {
      color: var(--text-dark) !important;
      margin-left: 1.2rem;
      font-weight: 600;
      position: relative;
    }
    .nav-link:hover { color: var(--primary-color) !important; }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -6px;
      left: 0;
      width: 0;
      height: 2px;
      background-color: var(--primary-color);
      transition: var(--transition);
    }
    .nav-link:hover::after { width: 100%; }

    /* ===== Hero ===== */
    .hero {
      padding: 4.5rem 0 5.2rem;
      background: linear-gradient(120deg, var(--primary-color), #3b82f6);
      color: #fff;
      text-align: center;
    }

    .hero-title {
      font-size: 3rem;
      font-weight: 900;
      margin-bottom: 0.9rem;
      line-height: 1.15;
      letter-spacing: 0.2px;
    }

    .hero-kicker {
      display: block;
      margin-top: 0.65rem;
      font-size: 1.45rem;
      font-weight: 800;
      opacity: 0.95;
      letter-spacing: 0.3px;
    }

    .hero p {
      font-size: 1.1rem;
      opacity: 0.92;
      max-width: 680px;
      margin: 0 auto 1.8rem;
    }

    .btn-download {
      background-color: #fff;
      color: var(--primary-color) !important;
      border: none;
      padding: 0.95rem 1.8rem;
      font-weight: 800;
      border-radius: 12px;
      transition: var(--transition);
      box-shadow: 0 10px 24px rgba(0, 0, 0, 0.14);
      display: inline-flex;
      align-items: center;
      gap: 8px;
      white-space: nowrap;
    }
    .btn-download:hover {
      background-color: #f3f4f6;
      transform: translateY(-2px);
      box-shadow: 0 14px 28px rgba(0, 0, 0, 0.16);
    }

    /* 安装流程按钮：与下载按钮统一风格 */
    .btn-guide {
      padding: 0.95rem 1.2rem;
      font-weight: 800;
      border-radius: 12px;
      border: 2px solid rgba(255,255,255,0.85);
      color: #fff;
      background: transparent;
      transition: var(--transition);
      display: inline-flex;
      align-items: center;
      gap: 8px;
      white-space: nowrap;
    }
    .btn-guide:hover {
      transform: translateY(-2px);
      border-color: #fff;
      background: rgba(255,255,255,0.12);
      color: #fff;
    }

    /* ===== Section title ===== */
    .section-title {
      font-size: 2rem;
      font-weight: 900;
      text-align: center;
      margin-bottom: 2.6rem;
      position: relative;
    }
    .section-title::after {
      content: '';
      display: block;
      width: 64px;
      height: 3px;
      background-color: var(--primary-color);
      margin: 0.85rem auto 0;
      border-radius: 99px;
    }

    /* ===== Feature cards ===== */
    .feature-card {
      background-color: #fff;
      border: none;
      border-radius: 14px;
      padding: 2rem 1.5rem;
      text-align: center;
      box-shadow: var(--card-shadow);
      transition: var(--transition);
      height: 100%;
    }
    .feature-card:hover {
      transform: translateY(-5px);
      box-shadow: 0 14px 30px rgba(0, 0, 0, 0.08);
    }
    .feature-icon {
      font-size: 2.4rem;
      color: var(--primary-color);
      margin-bottom: 1.1rem;
    }
    .feature-card h5 {
      font-weight: 900;
      margin-bottom: 0.7rem;
    }
    .feature-card p {
      color: var(--text-gray);
      font-size: 0.95rem;
      margin: 0;
    }

    /* ===== FAQ ===== */
    .faq-section { padding: 1.5rem 0 5rem; }

    .accordion-item {
      border: 1px solid #e5e7eb;
      border-radius: 12px !important;
      margin-bottom: 1rem;
      overflow: hidden;
      box-shadow: 0 4px 14px rgba(0,0,0,0.04);
    }
    .accordion-button {
      font-weight: 700;
      border: none;
      padding: 1.1rem 1.25rem;
      background-color: #fff !important;
    }
    .accordion-button:not(.collapsed) {
      color: var(--primary-color);
      box-shadow: none;
    }
    .accordion-body {
      padding: 0 1.25rem 1.2rem;
      color: var(--text-gray);
    }

    /* ===== Footer ===== */
    footer {
      background-color: var(--text-dark);
      color: #d1d5db;
      padding: 3.5rem 0 2rem;
    }
    .footer-col h5 {
      color: #fff;
      font-size: 1.1rem;
      margin-bottom: 1.2rem;
      font-weight: 900;
    }
    .footer-links { list-style: none; padding: 0; margin: 0; }
    .footer-links li { margin-bottom: 0.7rem; }
    .footer-links a {
      color: #d1d5db;
      text-decoration: none;
      transition: var(--transition);
    }
    .footer-links a:hover { color: #fff; margin-left: 4px; }

    .copyright {
      text-align: center;
      padding-top: 1.8rem;
      margin-top: 1.8rem;
      border-top: 1px solid #374151;
      font-size: 0.9rem;
      color: #b7c1d1;
    }

    /* ===== Floating Support ===== */
    .floating-support {
      position: fixed;
      right: 20px;
      bottom: 22px;
      z-index: 9999;
      display: flex;
      align-items: center;
      gap: 8px;
      padding: 10px 14px;
      background: var(--primary-color);
      color: #fff;
      text-decoration: none;
      border-radius: 999px;
      box-shadow: 0 10px 26px rgba(37, 99, 235, 0.35);
      font-size: 0.95rem;
      font-weight: 800;
      transition: all 0.25s ease;
    }
    .floating-support i { font-size: 1.1rem; }
    .floating-support:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: 0 14px 30px rgba(37, 99, 235, 0.45);
      color: #fff;
    }

    /* ===== Responsive ===== */
    @media (max-width: 992px) {
      .nav-link { margin-left: 0; }
      .navbar-collapse { padding-top: 0.5rem; }
    }

    @media (max-width: 768px) {
      body { padding-top: 66px; }
      .navbar { padding: 0.45rem 0; }

      .logo-img { height: 34px; border-radius: 9px; }
      .brand-text { display: inline-block; }

      .hero { padding: 4.4rem 0 3.4rem; }
      .hero-title { font-size: 2.05rem; }
      .hero-kicker { font-size: 1.05rem; margin-top: 0.55rem; }

      .hero p {
        font-size: 1rem;
        margin-bottom: 1.4rem;
        padding: 0 0.5rem;
      }

      /* 按钮在手机端更舒服：自动换行居中 */
      .hero-actions{
        display:flex;
        justify-content:center;
        gap: 12px;
        flex-wrap: wrap;
      }

      .btn-download { padding: 0.82rem 1.3rem; }
      .btn-guide { padding: 0.82rem 1.1rem; }

      .section-title { font-size: 1.55rem; margin-bottom: 2rem; }

      .floating-support {
        right: 16px;
        bottom: 16px;
        padding: 12px;
        border-radius: 999px;
      }
      .floating-support span { display: none; }
    }