* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    background-color: #f5f5f5;
    color: #333;
}

.container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 1rem;
}

h1 {
    text-align: center;
    color: #2c3e50;
    margin-bottom: 2rem;
}

h2 {
    color: #2c3e50;
    margin: 1.5rem 0;
}

.course-form {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.input-group {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

input, select {
    padding: 0.5rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
}

input[type="text"] {
    flex: 2;
}

input[type="number"] {
    flex: 1;
}

.semester-select {
    min-width: 120px;
    cursor: pointer;
}

button {
    background-color: #3498db;
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #2980b9;
}

/* 学期分组样式 */
.semester-group {
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    overflow: hidden;
}

.semester-title {
    padding: 1rem 1.5rem;
    margin: 0;
    background-color: #f8f9fa;
    color: #2c3e50;
    border-bottom: 1px solid #eee;
    font-size: 1.2rem;
}

.semester-group table {
    margin: 0;
    border-radius: 0;
    box-shadow: none;
}

.semester-group-stats {
    padding: 0.8rem 1.5rem;
    background-color: #f8f9fa;
    border-top: 1px solid #eee;
    color: #2c3e50;
    font-weight: 500;
}

table {
    width: 100%;
    border-collapse: collapse;
    background: white;
}

th, td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid #eee;
}

th {
    background-color: #f8f9fa;
    font-weight: 600;
}

.delete-btn {
    background-color: #e74c3c;
    margin-left: 0.5rem;
}

.delete-btn:hover {
    background-color: #c0392b;
}

.edit-btn {
    background-color: #2ecc71;
}

.edit-btn:hover {
    background-color: #27ae60;
}

.result {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    margin-top: 2rem;
}

.result-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-top: 1rem;
}

.result-item p {
    font-size: 1.1rem;
    margin: 0.5rem 0;
}

.result span {
    font-weight: bold;
    color: #2c3e50;
}

.semester-result {
    border-left: 1px solid #eee;
    padding-left: 2rem;
}

.semester-stat {
    margin: 0.5rem 0;
    padding: 0.5rem;
    background-color: #f8f9fa;
    border-radius: 4px;
}

.semester-stat span {
    margin-left: 0.5rem;
}

/* 模态框样式 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
}

.modal-content {
    background-color: white;
    margin: 10% auto;
    width: 90%;
    max-width: 500px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    position: relative;
}

.modal-header {
    padding: 1rem 1.5rem;
    border-bottom: 1px solid #eee;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h3 {
    margin: 0;
    color: #2c3e50;
}

.close {
    font-size: 1.5rem;
    font-weight: bold;
    color: #666;
    cursor: pointer;
}

.close:hover {
    color: #333;
}

.modal-body {
    padding: 1.5rem;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: #2c3e50;
    font-weight: 500;
}

.form-group input, .form-group select {
    width: 100%;
}

.modal-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid #eee;
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
}

.primary-btn {
    background-color: #3498db;
}

.primary-btn:hover {
    background-color: #2980b9;
}

@media (max-width: 768px) {
    .result-grid {
        grid-template-columns: 1fr;
    }
    
    .semester-result {
        border-left: none;
        border-top: 1px solid #eee;
        padding-left: 0;
        padding-top: 1rem;
    }
}

.data-actions {
    margin-top: 1rem;
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    padding-top: 1rem;
    border-top: 1px solid #eee;
}

.secondary-btn {
    background-color: #95a5a6;
}

.secondary-btn:hover {
    background-color: #7f8c8d;
}

.danger-btn {
    background-color: #e74c3c;
}

.danger-btn:hover {
    background-color: #c0392b;
}

/* 添加返回按钮样式 */
.back-button {
    margin-bottom: 1rem;
    padding: 0.5rem 0;
}

.return-btn {
    display: inline-flex;
    align-items: center;
    padding: 0.5rem 1rem;
    background-color: #4a4a4a;
    color: white;
    text-decoration: none;
    border-radius: 4px;
    transition: background-color 0.3s;
}

.return-btn:hover {
    background-color: #333;
}

.return-btn i {
    margin-right: 0.5rem;
}

/* 序号列样式 */
td:first-child, th:first-child {
    width: 80px;
    min-width: 80px;
    text-align: center;
}

/* 序号列的数字保持灰色 */
td:first-child {
    color: #666;
}

/* 序号列的标题为黑色 */
th:first-child {
    color: #2c3e50;
    font-weight: 600;
}

/* 总课程数统计样式 */
.total-courses-stats {
    margin-top: 2rem;
    padding: 1rem 1.5rem;
    background-color: #f8f9fa;
    border-radius: 8px;
    text-align: center;
    font-size: 1.2rem;
    color: #2c3e50;
    font-weight: 500;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.total-courses-stats p {
    margin: 0;
}

/* 搜索框样式 */
.search-box {
    margin-bottom: 1.5rem;
    position: relative;
    max-width: 400px;
}

.search-box input {
    width: 100%;
    padding: 0.8rem 1rem 0.8rem 2.5rem;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.search-box input:focus {
    border-color: #3498db;
    box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
    outline: none;
}

.search-icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: #95a5a6;
}

/* 搜索结果高亮样式 */
.highlight {
    background-color: #fff3cd;
    padding: 0 2px;
    border-radius: 2px;
}

/* 无搜索结果样式 */
.no-results {
    text-align: center;
    padding: 2rem;
    background-color: #f8f9fa;
    border-radius: 8px;
    color: #666;
    font-size: 1.1rem;
}

.no-results p {
    margin: 0;
}