body {
      background: linear-gradient(135deg, #6a11cb 0%, #2575fc 100%);
      min-height: 100vh;
      display: flex;
      align-items: center;
      padding: 20px 0;
    }
    .calculator-card {
      background: rgba(255, 255, 255, 0.92);
      border-radius: 20px;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
      overflow: hidden;
      max-width: 600px;
      margin: 0 auto;
    }
    .card-header {
      background: linear-gradient(to right, #3498db, #2c3e50);
      color: white;
      padding: 25px 20px;
      text-align: center;
    }
    .card-body {
      padding: 30px;
    }
    .btn-primary {
      background: linear-gradient(to right, #3498db, #2c3e50);
      border: none;
      transition: all 0.3s;
      font-weight: 600;
    }
    .btn-primary:hover {
      transform: translateY(-2px);
      box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    }
    .result-box {
      background-color: #f8f9fa;
      border-radius: 5px;
      padding: 12px;
      margin-bottom: 10px;
      border-left: 4px solid #3498db;
    }
    .bi-people {
      font-size: 1.8rem;
      margin-bottom: 10px;
      color: #3498db;
    }
    .student-list {
      max-height: 200px;
      overflow-y: auto;
      margin: 15px 0;
      border: 1px solid #dee2e6;
      border-radius: 5px;
      padding: 10px;
    }
    .student-item {
      padding: 8px;
      border-bottom: 1px solid #eee;
    }
    .student-item:last-child {
      border-bottom: none;
    }