html { font-size: 16px; }
    body {
      margin: 0;
      font-family: 'PingFang SC', 'Microsoft YaHei', Arial, sans-serif;
      color: #222;
      background: #f6f8fa;
      min-height: 100vh;
    }
    .container {
      max-width: 900px;
      margin: auto;
      background: #fff;
      border-radius: 18px;
      box-shadow: 0 4px 32px rgba(30,80,180,0.08);
      padding: 0 1.5rem 2rem 1.5rem;
      margin-top: 2rem;
      margin-bottom: 2rem;
    }
    header {
      text-align: center;
      padding: 3rem 0 2rem 0;
      background: linear-gradient(90deg, #1da1f2 60%, #005bea 100%);
      color: #fff;
      border-radius: 18px 18px 0 0;
    }
    .main-title {
      font-size: 2.7rem;
      font-weight: bold;
      margin-bottom: 0.7rem;
      letter-spacing: 2px;
      text-shadow: 0 2px 8px rgba(30,80,180,0.10);
    }
    .subtitle {
      font-size: 1.25rem;
      margin-bottom: 2.2rem;
      opacity: 0.98;
      font-weight: 500;
    }
    .cta-btns {
      display: flex;
      justify-content: center;
      align-items: center; /* 垂直居中（如果有高度） */
      width: 100%;
      margin: 0 auto;
    }
    .cta-btn {
      background: linear-gradient(90deg, #1da1f2 60%, #005bea 100%);
      color: #fff;
      padding: 1.2rem 2.5rem;
      border-radius: 12px;
      text-decoration: none;
      font-size: 1.35rem;
      font-weight: 700;
      box-shadow: 0 4px 16px rgba(30,80,180,0.13);
      display: flex;
      align-items: center;
      gap: 0.7rem;
      transition: background 0.2s, transform 0.2s;
      border: none;
      outline: none;
      cursor: pointer;
      letter-spacing: 1px;
      position: relative;
      z-index: 2;
      width: auto; /* 让按钮宽度随内容自适应 */
      min-width: unset;
      max-width: 100%;
    }
    .cta-btn:hover {
      background: linear-gradient(90deg, #0d8ddb 0%, #1da1f2 100%);
      color: #fff;
      transform: translateY(-2px) scale(1.05);
      box-shadow: 0 6px 24px rgba(30,80,180,0.18);
    }
    section {
      margin: 2.5rem 0 0 0;
    }
    .card-list, .why-list {
      display: flex;
      flex-wrap: wrap;
      gap: 1.2rem;
      justify-content: center;
      margin-top: 1.5rem;
    }
    .card, .why-item {
      background: #fff;
      color: #222;
      border-radius: 16px;
      box-shadow: 0 2px 12px rgba(30,80,180,0.08);
      padding: 1.1rem 1rem 1.1rem 1rem;
      flex: 1 1 220px;
      min-width: 180px;
      max-width: 260px;
      text-align: center;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 80px;
      transition: box-shadow 0.2s, transform 0.2s;
    }
    .card-icon {
      font-size: 1.7rem;
      margin-bottom: 0.3rem;
    }
    .card > div:last-child, .why-item {
      font-size: 1rem;
      line-height: 1.5;
    }
    .card:hover, .why-item:hover {
      box-shadow: 0 6px 24px rgba(30,80,180,0.16);
      transform: translateY(-2px) scale(1.03);
    }
    h2 {
      font-size: 1.5rem;
      margin-top: 2rem;
      text-align: center;
      color: #1da1f2;
      font-weight: 600;
    }
    h3 {
      font-size: 1.1rem;
      margin-top: 1.5rem;
      color: #005bea;
    }
    .why-list {
      display: flex;
      flex-wrap: wrap;
      gap: 1.2rem;
      justify-content: center;
      margin-top: 1.2rem;
    }
    .why-item {
      background: #f6f8fa;
      color: #222;
      border-radius: 12px;
      padding: 1rem 1rem 1rem 1.5rem;
      flex: 1 1 180px;
      min-width: 140px;
      max-width: 320px;
      position: relative;
      font-size: 1rem;
      box-shadow: 0 1px 4px rgba(30,80,180,0.06);
    }
    .why-item:before {
      content: "💡";
      position: absolute;
      left: 0.7rem;
      top: 1.1rem;
      font-size: 1.2rem;
    }
    .steps {
      display: flex;
      flex-wrap: wrap;
      gap: 1.2rem;
      justify-content: center;
      margin-top: 1.2rem;
    }
    .step {
      background: #f6f8fa;
      color: #222;
      border-radius: 10px;
      padding: 0.7rem 0.7rem;
      flex: 1 1 120px;
      min-width: 100px;
      max-width: 180px;
      text-align: center;
      font-size: 0.98rem;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 60px;
      box-shadow: 0 1px 4px rgba(30,80,180,0.06);
    }
    .step-num {
      font-size: 1.2rem;
      color: #1da1f2;
      font-weight: bold;
      margin-bottom: 0.3rem;
    }
    .reviews {
      display: flex;
      flex-wrap: wrap;
      gap: 1.2rem;
      justify-content: center;
      margin-top: 1.2rem;
    }
    .review {
      background: #f6f8fa;
      color: #222;
      border-radius: 10px;
      padding: 1rem 1.2rem;
      flex: 1 1 180px;
      min-width: 120px;
      max-width: 240px;
      font-size: 0.98rem;
      box-shadow: 0 1px 4px rgba(30,80,180,0.06);
      position: relative;
      display: flex;
      flex-direction: column;
      align-items: flex-start;
      min-height: 60px;
    }
    .review .user {
      font-weight: bold;
      color: #1da1f2;
      font-size: 1rem;
      vertical-align: middle;
    }
    .review .stars {
      color: #ffb400;
      font-size: 1.1rem;
      margin-left: 0.5rem;
    }
    .faq dl { margin: 0; }
    .faq dt { font-weight: bold; margin-top: 1rem; color: #1da1f2; }
    .faq dd { margin: 0 0 1rem 0.5rem; color: #555; }
    footer {
      text-align: center;
      color: #888;
      font-size: 0.98rem;
      padding: 2rem 0 1rem 0;
      background: transparent;
    }
    .footer-link { color: #1da1f2; text-decoration: underline; }
    /* 移动端优化 */
    @media (max-width: 700px) {
      .container { padding: 0 0.5rem 1.5rem 0.5rem; }
      header { padding: 2rem 0 1.2rem 0; }
      .main-title { font-size: 1.3rem; }
      .cta-btn { font-size: 1rem; padding: 0.8rem 1.2rem; }
      .card, .why-item, .review, .step { min-width: 90px; max-width: 100%; }
      .card { padding: 0.6rem 0.6rem; min-height: 56px; }
      .card-icon { font-size: 1.1rem; }
      .card-list {
        flex-wrap: nowrap;
        overflow-x: auto;
        gap: 0.7rem;
        margin-left: -0.5rem;
        margin-right: -0.5rem;
        padding-left: 0.5rem;
        padding-right: 0.5rem;
        scrollbar-width: none;
      }
      .card-list::-webkit-scrollbar { display: none; }
      .card {
        min-width: 72vw;
        max-width: 78vw;
        padding: 0.6rem 0.6rem;
        min-height: 54px;
        font-size: 0.95rem;
      }
      .card-icon {
        font-size: 1.1rem;
        margin-bottom: 0.15rem;
      }
      .card > div:last-child {
        font-size: 0.95rem;
      }
    }
    @media (max-width: 500px) {
      .cta-btns { flex-direction: column; gap: 1rem; }
      .card-list, .why-list, .reviews, .steps { flex-direction: column; gap: 1rem; }
      .card-list { flex-direction: row; }
      .card {
        min-width: 82vw;
        max-width: 88vw;
        padding: 0.5rem 0.5rem;
        min-height: 44px;
        font-size: 0.92rem;
      }
      .card-icon { font-size: 1rem; }
      .card > div:last-child { font-size: 0.92rem; }
    }
    /* 移动端吸底按钮 */
    @media (max-width: 600px) {
      .mobile-fixed-cta {
        position: fixed;
        left: 0; right: 0; bottom: 0;
        background: #fff;
        padding: 0.7rem 0;
        z-index: 999;
        display: flex;
        justify-content: center;
        gap: 1.2rem;
        box-shadow: 0 -2px 12px rgba(30,80,180,0.10);
      }
      .mobile-fixed-cta .cta-btn {
        font-size: 1.25rem;      /* 增大字体 */
        padding: 1.2rem 0;       /* 增大内边距，上下更厚实 */
        border-radius: 10px;     /* 稍微更圆润 */
        width: 96vw;             /* 更宽 */
        max-width: 500px;        /* 最大宽度更大 */
        justify-content: center;
        background: linear-gradient(90deg, #1da1f2 60%, #005bea 100%);
        color: #fff;
        font-weight: 700;        /* 字体加粗 */
      }
      .card, .step, .review { padding: 0.5rem 0.5rem; min-height: 48px; }
      .card-icon { font-size: 1rem; }
    }