:root { --main: #2e74d1; --bg: #f7fafd; }
    html, body { margin: 0; padding: 0; background: var(--bg); }
    body { font-family: "Segoe UI", Arial, sans-serif; color: #234; }
    .container {
      max-width: 370px;
      margin: 34px auto 0 auto;
      background: #fff;
      border-radius: 18px;
      box-shadow: 0 4px 22px #2e74d111;
      padding: 28px 16px 21px 16px;
    }
    .title { text-align: center; font-size: 1.25em; color: var(--main); font-weight: bold; margin-bottom: 8px; }
    .desc { text-align: center; color: #4a73a5; font-size: 1.02em; margin-bottom: 20px; }
    .form-row {
      display: flex; flex-direction: column; gap: 7px; margin-bottom: 13px;
    }
    .form-row label { font-size: 1em; color: #2264c3; font-weight: 500; }
    .form-row input[type="number"] {
      box-sizing: border-box;
      padding: 10px 10px;
      border-radius: 7px;
      border: 1.2px solid #bfd8ff;
      font-size: 1.09em;
      width: 100%;
      background: #fafdff;
      color: #234;
      transition: border 0.15s;
    }
    .form-row input[type="number"]:focus { border-color: var(--main); }
    .btn {
      background: var(--main); color: #fff; border: none; border-radius: 8px;
      padding: 13px 0; width: 100%; font-size: 1.13em; font-weight: bold; cursor: pointer;
      margin-top: 7px; margin-bottom: 9px; box-shadow: 0 2px 12px #2e74d122;
      transition: background 0.16s;
    }
    .btn:active { background: #194e99; }
    .result {
      background: #eaf3ff;
      border-radius: 12px;
      color: #144c91;
      font-size: 1.07em;
      padding: 13px 11px 9px 11px;
      text-align: center;
      margin-bottom: 9px;
      min-height: 44px;
      font-weight: 500;
      word-break: break-word;
    }
    .bmi-table {
      margin: 15px auto 5px auto;
      border-collapse: collapse;
      width: 100%;
      font-size: 0.98em;
      background: #fafdff;
      box-shadow: 0 2px 8px #bbe7ff24;
    }
    .bmi-table th, .bmi-table td {
      border: 1px solid #c5e1fa;
      padding: 6px 4px;
      text-align: center;
    }
    .bmi-table th { background: #e1eefe; color: #2274ba; }
    .bmi-table td { background: #fff; }
    section#faq { margin-top: 26px; }
    section#faq h2 { margin-bottom: 13px; color: #2e74d1; font-size: 1.14em; text-align: center; }
    section#faq dt { font-weight: bold; margin-top: 9px; }
    section#faq dd { margin: 0 0 7px 0; font-size: 0.99em; color: #24528a; }
    .footer { color: #789; text-align: center; font-size: 0.94em; margin-top: 16px; }
    #backBtn {
      position: fixed; left: 50%; bottom: 32px; transform: translateX(-50%);
      background: #2e74d1; color: #fff; font-weight: 700; border: none; border-radius: 2rem;
      padding: 0.58em 1.5em; box-shadow: 0 4px 16px #2e74d166; font-size: 1.09em; text-decoration: none;
      cursor: pointer; letter-spacing: 0.01em; transition: background 0.15s, transform 0.12s; z-index: 2000;
    }
    #backBtn:hover { background: #144c91; transform: translateX(-50%) scale(1.04); }
    @media (max-width: 520px) {
      .container { max-width: 98vw; padding: 11px 2vw 10px 2vw; }
      #backBtn { bottom: 18px; font-size: 0.98em; padding: 0.48em 1em; }
    }