.brand {
    font-weight: 800;
    color: #1e5fa8;
    font-size: 18px;
    text-decoration: none;
  }
  .brand span { color: #ffb142; }
  .topnav ul {
    list-style: none;
    display: flex;
    gap: 20px;
    font-size: 15px;
  }
  .topnav a {
    color: #345;
    text-decoration: none;
    padding: 4px 0;
    border-bottom: 2px solid transparent;
  }
  .topnav a:hover, .topnav a.active {
    color: #1e5fa8;
    border-bottom-color: #ffb142;
  }

 ol li,ul li,.note{ line-height:30px; font-size:1.2rem;}

  .paper-banner {
    background: #eaf4ff;
    border: 1px solid #cfe4f9;
    border-radius: 12px;
    padding: 14px;
    margin-top: 16px;
    font-size: 14px;
    color: #1e5fa8;
    display: flex;
    flex-wrap: wrap;
    gap: 12px 24px;
    align-items: center;
  }
  .paper-banner b { color: #1e5fa8; }
  .paper-banner .dot { color: #b8d4f0; }

  header.hero {
    background: linear-gradient(135deg, #1e5fa8, #2e86de);
    color: #fff;
    padding: 42px 24px;
    border-radius: 0 0 24px 24px;
    box-shadow: 0 6px 18px rgba(30,95,168,.25);
    margin-top: 16px;
  }

    header.hero p {
        font-size: 15px;
        opacity: .96;
        max-width: 660px;
        color:#f8fbff;
    }
  .tag {
    display: inline-block;
    background: #ffb142;
    color: #4a2c00;
    font-size: 13px;
    padding: 4px 12px;
    border-radius: 999px;
    margin-top: 14px;
    font-weight: 700;
  }
  .tag + .tag { margin-left: 8px; background: #fff; color: #1e5fa8; }

  section {
    background: #fff;
    border-radius: 16px;
    padding: 28px;
    margin-top: 24px;
    box-shadow: 0 4px 14px rgba(0,0,0,.05);
  }
  section h2 {
    font-size: 22px;
    color: #1e5fa8;
    border-left: 6px solid #ffb142;
    padding-left: 12px;
    margin-bottom: 18px;
  }
  section h3 {
    font-size: 17px;
    color: #2e86de;
    margin: 20px 0 8px;
  }
  section h4 {
    font-size: 15px;
    color: #1e5fa8;
    margin: 14px 0 6px;
  }
  p { margin: 8px 0; }
  ul, ol { margin: 8px 0 8px 22px; }
  li { margin: 6px 0; }

  .formula {
    font-family: "Cambria Math", "Times New Roman", serif;
    font-size: 16px;
    background: #f0f6ff;
    padding: 2px 8px;
    border-radius: 6px;
    display: inline-block;
    margin: 2px 0;
  }

  .note {
    background: #fff8e6;
    border-left: 4px solid #ffb142;
    padding: 12px 16px;
    border-radius: 8px;
    margin: 12px 0;
    font-size: 14px;
  }
  .teach-note {
    background: #eef7ff;
    border-left: 4px solid #2e86de;
    padding: 12px 16px;
    border-radius: 8px;
    margin: 12px 0;
    font-size: 14px;
  }
  .teach-note b { color: #1e5fa8; }

  .grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
  .grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
  @media (max-width: 760px) {
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
  }

  .card {
    background: #f8fbff;
    border: 1px solid #dbe9f7;
    border-radius: 12px;
    padding: 16px;
  }
  .card h4 { color: #1e5fa8; font-size: 1.6rem; margin-bottom: 8px; }
.warn {
    color: #d63031;
    font-weight: 700;
  
}
  .ok { color: #00a86b; font-weight: 700; }
  .mix { color: #e67e22; font-weight: 700; }

  table { width: 100%; border-collapse: collapse; margin: 12px 0; font-size: 15px; }
  th, td { border: 1px solid #dbe9f7; padding: 10px 12px; text-align: left; vertical-align: top; }
  th { background: #eaf4ff; color: #1e5fa8; }

  details {
    background: #f8fbff;
    border: 1px solid #dbe9f7;
    border-radius: 10px;
    padding: 12px 16px;
    margin: 10px 0;
  }
  details summary {
    cursor: pointer;
    font-weight: 700;
    color: #1e5fa8;
    font-size: 15.5px;
    list-style: none;
  }
  details summary::-webkit-details-marker { display: none; }
  details summary::before {
    content: "＋ ";
    color: #2e86de;
    font-weight: 700;
  }
  details[open] summary::before {
    content: "－ ";
  }
  details[open] summary { margin-bottom: 8px; }
  details .faq-a {
    font-size: 14.5px;
    color: #345;
    line-height: 1.8;
  }
  details .faq-a ul { margin: 6px 0 6px 22px; }