/* roulang page: index */
:root {
      --primary-deep: #1A1C1E;
      --accent-signal: #1DB954;
      --bg-light: #F8F9FA;
      --bg-white: #FFFFFF;
      --text-body: #4A4D50;
      --text-muted: #6C757D;
      --border-light: #DEE2E6;
      --shadow-sm: 0 2px 16px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 30px rgba(0,0,0,0.08);
      --radius-md: 8px;
      --transition-base: all 0.3s ease;
      --font-mono: "SF Mono", "Menlo", "Courier New", monospace;
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
      background-color: var(--bg-white);
      color: var(--text-body);
      line-height: 1.8;
      margin: 0;
      overflow-x: hidden;
    }
    h1, h2, h3, h4, .h1, .h2, .h3, .h4 {
      color: var(--primary-deep);
      font-weight: 500;
      letter-spacing: 0;
    }
    h1 {
      font-weight: 600;
      font-size: 3.5rem;
      letter-spacing: -0.5px;
      line-height: 1.2;
    }
    h2 {
      font-weight: 500;
      font-size: 2.5rem;
      margin-bottom: 0.5rem;
      display: inline-block;
      position: relative;
    }
    h2::after {
      content: '';
      display: block;
      width: 40px;
      height: 2px;
      background-color: var(--accent-signal);
      margin-top: 0.75rem;
    }
    h3 {
      font-weight: 500;
      font-size: 1.5rem;
    }
    .text-mono {
      font-family: var(--font-mono);
      font-weight: 300;
      font-size: 3rem;
      color: var(--accent-signal);
      line-height: 1.2;
    }
    .container-custom {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }
    /* 导航 */
    .navbar-custom {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1030;
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(0,0,0,0.05);
      transition: var(--transition-base);
      height: 72px;
      display: flex;
      align-items: center;
    }
    .navbar-brand {
      font-weight: 600;
      font-size: 1.75rem;
      letter-spacing: 2px;
      color: var(--primary-deep) !important;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .brand-icon {
      font-size: 2rem;
      color: var(--accent-signal);
    }
    .nav-link {
      color: var(--primary-deep) !important;
      font-weight: 500;
      margin: 0 1rem;
      position: relative;
      padding: 0.25rem 0 !important;
      transition: color 0.2s;
      font-size: 0.95rem;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 50%;
      transform: translateX(-50%) scaleX(0);
      width: 100%;
      height: 2px;
      background: var(--accent-signal);
      transition: transform 0.25s ease;
      transform-origin: center;
    }
    .nav-link:hover::after,
    .nav-link.active::after {
      transform: translateX(-50%) scaleX(1);
    }
    .nav-link:hover {
      color: var(--accent-signal) !important;
    }
    /* 汉堡菜单 */
    .navbar-toggler {
      border: none;
      box-shadow: none;
    }
    .navbar-toggler-icon {
      background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(26, 28, 30, 0.9)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
    }
    @media (max-width: 991.98px) {
      .navbar-collapse {
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(20px);
        padding: 2rem;
        border-radius: 0 0 var(--radius-md) var(--radius-md);
      }
      .nav-link {
        margin: 0.75rem 0;
        font-size: 1.2rem;
      }
      h1 {
        font-size: 2.5rem;
      }
      h2 {
        font-size: 2rem;
      }
    }
    /* 板块间距 */
    section {
      padding: 120px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 80px 0;
      }
    }
    /* 按钮 */
    .btn-primary-custom {
      background: var(--primary-deep);
      color: white;
      border: none;
      padding: 0.8rem 2.2rem;
      border-radius: var(--radius-md);
      font-weight: 500;
      transition: var(--transition-base);
      letter-spacing: 0.5px;
    }
    .btn-primary-custom:hover {
      background: var(--accent-signal);
      color: var(--primary-deep);
      transform: translateY(-2px);
    }
    .btn-outline-custom {
      background: transparent;
      color: var(--primary-deep);
      border: 1px solid var(--primary-deep);
      padding: 0.8rem 2.2rem;
      border-radius: var(--radius-md);
      font-weight: 500;
      transition: var(--transition-base);
    }
    .btn-outline-custom:hover {
      border-color: var(--accent-signal);
      color: var(--accent-signal);
      background: transparent;
      transform: translateY(-2px);
    }
    /* 卡片 */
    .card-custom {
      background: var(--bg-white);
      border: none;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
      padding: 2.5rem;
      height: 100%;
      transition: var(--transition-base);
    }
    .card-custom:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    .icon-accent {
      color: var(--accent-signal);
      font-size: 2rem;
      margin-bottom: 1.5rem;
    }
    /* 错落栅格 */
    .grid-special {
      display: grid;
      grid-template-columns: 1.5fr 1fr;
      gap: 2rem;
    }
    .grid-right-stack {
      display: flex;
      flex-direction: column;
      gap: 2rem;
    }
    @media (max-width: 991.98px) {
      .grid-special {
        grid-template-columns: 1fr;
      }
    }
    /* 深色证言区 */
    .bg-deep {
      background: var(--primary-deep);
      color: white;
    }
    .quote-mark {
      font-size: 6rem;
      opacity: 0.05;
      color: white;
      line-height: 1;
      user-select: none;
    }
    /* FAQ */
    .accordion-button {
      font-weight: 500;
      font-size: 1.1rem;
      color: var(--primary-deep);
      background: transparent;
      box-shadow: none;
      border-bottom: 1px solid var(--border-light);
      padding: 1.2rem 0;
    }
    .accordion-button:not(.collapsed) {
      color: var(--accent-signal);
      background: transparent;
      box-shadow: none;
    }
    .accordion-button::after {
      display: none;
    }
    .accordion-button .faq-icon {
      transition: transform 0.2s;
      margin-right: 12px;
      font-weight: 400;
    }
    .accordion-button:not(.collapsed) .faq-icon {
      transform: rotate(45deg);
    }
    .accordion-body {
      color: var(--text-muted);
      line-height: 1.8;
      padding: 0.8rem 0 1.5rem;
    }
    /* 表单底线风格 */
    .form-underline {
      border: none;
      border-bottom: 1px solid var(--border-light);
      border-radius: 0;
      padding-left: 0;
      background: transparent;
      transition: border-color 0.2s;
    }
    .form-underline:focus {
      border-bottom: 2px solid var(--accent-signal);
      box-shadow: none;
      outline: none;
    }
    /* 图形动画容器 */
    .hero-visual {
      position: relative;
      width: 100%;
      height: 300px;
    }
    svg .wave-path {
      stroke: var(--accent-signal);
      stroke-width: 2;
      fill: none;
      stroke-dasharray: 1000;
      stroke-dashoffset: 1000;
      animation: drawWave 3s ease-out forwards;
    }
    @keyframes drawWave {
      to { stroke-dashoffset: 0; }
    }
    footer {
      border-top: 1px solid var(--border-light);
      padding: 2rem 0;
      font-size: 0.85rem;
      color: var(--text-muted);
    }