.site-header {
    background-color: #ffffff;
    padding: 10px 20px;
    border-bottom: 2px solid #ddd;
    position: sticky;
    top: 0;
    z-index: 1000;
  }
  
  .header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
  }
  
  .logo img {
    max-width: 100%;
    height: auto;
    display: block;
  }
  
  .site-nav ul {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
  }
  
  .site-nav li {
    margin-left: 20px;
  }
  
  .site-nav a {
    text-decoration: none;
    color: #333;
    font-weight: bold;
    font-size: 14px;
  }
  
  .menu-toggle {
    display: none;
    font-size: 24px;
    background: none;
    border: none;
    cursor: pointer;
  }
  
  @media (max-width: 768px) {
    .site-nav {
      display: none;
      flex-direction: column;
      position: absolute;
      top: 60px;
      right: 20px;
      background-color: white;
      border: 1px solid #ccc;
      width: 200px;
    }
  
    .site-nav.open {
      display: flex;
    }
  
    .site-nav li {
      margin: 10px 0;
      text-align: right;
      padding-right: 10px;
    }
  
    .menu-toggle {
      display: block;
    }
  }
  
  .site-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 20px;
    background-color: #f5f5f5;
    position: relative;
  }
  
  .site-logo {
    height: 40px;
  }
  
  
  .site-nav .menu {
    list-style: none;
    display: flex;
    gap: 20px;
    margin: 0;
    padding: 0;
  }
  
  .site-nav .menu li a {
    text-decoration: none;
    color: #333;
    font-weight: bold;
  }
  
  .menu-toggle {
    display: none;
    font-size: 24px;
    background: none;
    border: none;
  }
  
  .subject-banner img {
    width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
  }
  
  @media (max-width: 768px) {
    .menu-toggle {
      display: block;
    }
  
    .site-nav {
      display: none;
      flex-direction: column;
      position: absolute;
      top: 100%;
      right: 0;
      background-color: #f5f5f5;
      width: 100%;
      z-index: 10;
    }
  
    .site-nav.open {
      display: flex;
    }
  
    .site-nav .menu {
      flex-direction: column;
      gap: 10px;
      padding: 10px;
    }
  }
  
  @import url('https://fonts.googleapis.com/css2?family=Kosugi+Maru&display=swap');
  
  nav.site-nav a {
    font-family: 'Kosugi Maru', sans-serif;
    font-weight: normal;
    font-size: 14px; 
  }
  .description-box {
    background-color: #f8f8f8;
    border-radius: 12px;
    padding: 20px;
    margin: 30px auto;
    max-width: 800px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    font-family: 'Kosugi Maru', sans-serif;
  }
  
  .description-header {
    display: flex;
    align-items: center;
    margin-bottom: 16px;
  }
  
  .desc-icon {
    width: 28px;
    height: 28px;
    margin-right: 12px;
  }
  
  .desc-title {
    font-size: 20px;
    font-weight: bold;
    color: #0077cc;
    margin: 0;
  }
  
  .description-box-p {
    font-size: 16px;
    color: #333;
    line-height: 1.75;
    margin-bottom: 12px;
  }
  
  .section-message {
    font-size: 18px;
    font-weight: bold;
    color: #0055cc;
    margin-top: 24px;
  }
  
  .map-description {
    max-width: 800px;
    margin: 2rem auto;
    padding: 1.5rem 2rem;
    background: #ffffff;
    border-left: 8px solid #42a5f5;
    border-radius: 12px;
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.05);
    font-size: 1.1rem;
    line-height: 1.8;
    color: #333;
    text-align: left;
    position: relative;
  }
  
  .map-description h2 {
    font-size: 1.5rem;
    color: #1e88e5;
    margin-bottom: 1rem;
  }
  
  .map-description::before {
    content: "🧪";
    font-size: 2rem;
    position: absolute;
    top: 1rem;
    left: 1rem;
  }
  
  .chem-structure {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-top: 50px;
  }
  
  .row.top-row {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
  }
  
  .chem-btn {
    background-color: #1976d2;
    color: white;
    text-decoration: none;
    padding: 12px 20px;
    border-radius: 8px;
    font-weight: bold;
    font-size: 14px;
    min-width: 100px;
    text-align: center;
    display: inline-block;
    box-shadow: 2px 2px 6px rgba(0,0,0,0.1);
    transition: background-color 0.2s;
  }
  
  .social-icons {
    text-align: center;
    margin-top: 20px;
  }
  
  .icon-link {
    margin: 0 10px;
    font-size: 28px;
    color: #444;
    transition: color 0.3s ease;
  }
  
  .icon-link:hover {
    color: #1da1f2
  }