body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
    background-color: #f5f5f5;
}
.button-group {
  padding: 0px;
  text-align: left;
}

.btn {
  background-color: #1900ff;
  color: white;
  padding: 1px 1px;
  margin: 5px;
  border-radius: 5px;
  text-decoration: none;
  font-size: 12px;
  display: inline-block;
  transition: background-color 0.3s ease;
  width: 30px; /* Fixed width */
  height: 20px; /* Fixed width */
  text-align: center;
}

.btn:hover {
  background-color: #ff7f50; /* Orange background on hover */
}

.btn:active {
  background-color: #ff4500; /* Darker orange when clicked */
}



.container {
    max-width: 1200px;
    margin: 0 auto;
    background-color: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
.header {
    text-align: center;
    margin-bottom: 20px;
    border-bottom: 2px solid #333;
    padding-bottom: 10px;
}
.header h1 {
    margin: 0;
    color: #333;
}
.header p {
    margin: 5px 0;
    color: #666;
}
.form-group {
    margin-bottom: 15px;
}
.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}
.teacher-info {
    margin-bottom: 20px;
    padding: 15px;
    background-color: #fff8e1;
    border-radius: 5px;
}
.teacher-info input, .teacher-info select {
    padding: 8px;
    margin-right: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    width: 250px;
}
.subject-selector {
    margin-bottom: 20px;
    padding: 15px;
    background-color: #f0f8ff;
    border-radius: 5px;
}
.subject-selector select {
    padding: 8px 12px;
    margin-right: 10px;
    border-radius: 4px;
    border: 1px solid #ddd;
    width: 200px;
}
button {
    padding: 8px 16px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
}
button:hover {
    background-color: #45a049;
}
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 20px;
}
th, td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: center;
}
th {
    background-color: #f2f2f2;
    font-weight: bold;
}
tr:nth-child(even) {
    background-color: #f9f9f9;
}
input[type="number"] {
    width: 60px;
    padding: 5px;
    border: 1px solid #ddd;
    border-radius: 3px;
    text-align: center;
}
.submit-btn {
    display: block;
    width: 200px;
    margin: 20px auto;
    padding: 10px;
    background-color: #2196F3;
    color: white;
    font-size: 16px;
}
.submit-btn:hover {
    background-color: #0b7dda;
}
.hidden {
    display: none;
}
.error {
    border-color: red !important;
}
.error-message {
    color: red;
    margin-top: 5px;
    font-size: 14px;
}
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
    margin-left: 10px;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}