body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f5f5f5;
  margin: 0;
  padding: 0;
  color: #333;
}
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
}
header {
  background-color: #2c3e50;
  color: white;
  padding: 20px;
  margin-bottom: 30px;
  border-radius: 5px;
}
header h1 {
  margin: 0;
  font-size: 2em;
}
nav {
  margin-top: 15px;
}
nav a {
  color: white;
  text-decoration: none;
  margin-right: 15px;
  padding: 5px 10px;
  border-radius: 3px;
  transition: background-color 0.3s;
}
nav a:hover {
  background-color: #34495e;
}
.flash-messages {
  margin-top: 15px;
}
.flash {
  padding: 10px 15px;
  border-radius: 5px;
  margin-bottom: 10px;
  font-weight: bold;
}
.flash.success {
  color: green;
}
.flash.error {
  color: red;
}
.form-container {
  background-color: white;
  padding: 30px;
  border-radius: 5px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}
.form-container h2 {
  margin-top: 0;
  color: #2c3e50;
  padding-bottom: 15px;
  border-bottom: 1px solid #eee;
}
.form-group {
  margin-bottom: 20px;
}
.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  color: #2c3e50;
}
.form-group input,
.form-group select {
  width: 100%;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 16px;
}
.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: #3498db;
}
.submit-btn {
  background-color: #3498db;
  color: white;
  border: none;
  padding: 12px 20px;
  font-size: 16px;
  border-radius: 4px;
  cursor: pointer;
  transition: background-color 0.3s;
}
.submit-btn:hover {
  background-color: #2980b9;
}
.students-list h3 {
  margin-top: 30px;
  color: #2c3e50;
  padding-bottom: 10px;
}
.student-item {
  margin-bottom: 15px;
  padding: 15px;
  background-color: #f9f9f9;
  border-radius: 4px;
  transition: background-color 0.2s;
}
.student-item:hover {
  background-color: #eee;
}
.student-item input[type="checkbox"] {
  margin-right: 10px;
}
.student-details {
  color: #7f8c8d;
  font-size: 0.9em;
  margin-left: 5px;
}
@media (max-width: 768px) {
  .container {
    padding: 10px;
  }

  header {
    padding: 15px;
  }

  .form-container {
    padding: 20px;
  }
}