body { font-family: Arial, sans-serif; }
    .sidebar {
      height: 100vh;
      position: fixed;
      top: 0; left: 0;
      width: 240px;
      background: #343a40;
      padding-top: 20px;
    }
    .sidebar a {
      display: block;
      color: #ddd;
      padding: 12px;
      text-decoration: none;
    }
    .sidebar a:hover { background: #495057; color: #fff; }
    .content {
      margin-left: 240px;
      padding: 20px;
    }
    @media (max-width: 768px) {
      .sidebar { display: none; }
      .content { margin-left: 0; }
    }
    footer {
      background: #343a40;
      color: #ccc;
      padding: 20px;
      text-align: center;
      margin-top: 40px;
    }
    .whatsapp-float {
      position: fixed;
      bottom: 25px; right: 25px;
      background-color: #25D366;
      color: white;
      border-radius: 50%;
      padding: 15px;
      font-size: 24px;
      z-index: 1000;
      box-shadow: 2px 2px 8px rgba(0,0,0,0.3);
    }
    .whatsapp-float:hover { background: #128C7E; color: white; }