/* ========== 全局样式 ========== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* ========== 导航栏 ========== */
.navbar {
    background: #fff;
    border-radius: 12px;
    padding: 15px 25px;
    margin-bottom: 25px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand a {
    font-size: 20px;
    font-weight: 700;
    color: #667eea;
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 5px;
}

.nav-links a {
    padding: 8px 18px;
    border-radius: 8px;
    color: #666;
    text-decoration: none;
    font-size: 14px;
    transition: all 0.3s;
}

.nav-links a:hover {
    background: #f0f0ff;
    color: #667eea;
}

.nav-links a.active {
    background: #667eea;
    color: #fff;
}

/* ========== 页面标题 ========== */
.page-header {
    background: #fff;
    border-radius: 12px;
    padding: 20px 25px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.page-header h2 {
    font-size: 22px;
    color: #333;
}

.header-actions {
    display: flex;
    gap: 10px;
}

/* ========== 按钮样式 ========== */
.btn {
    display: inline-block;
    padding: 10px 22px;
    border-radius: 8px;
    font-size: 14px;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: all 0.3s;
    font-weight: 500;
}

.btn-primary {
    background: #667eea;
    color: #fff;
}

.btn-primary:hover {
    background: #5a6fd6;
    transform: translateY(-1px);
}

.btn-success {
    background: #27ae60;
    color: #fff;
}

.btn-success:hover {
    background: #219a52;
    transform: translateY(-1px);
}

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

.btn-secondary:hover {
    background: #7f8c8d;
    transform: translateY(-1px);
}

.btn-sm {
    padding: 5px 12px;
    font-size: 12px;
}

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

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

.btn-delete {
    background: #e74c3c;
    color: #fff;
}

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

/* ========== 搜索栏 ========== */
.search-bar {
    background: #fff;
    border-radius: 12px;
    padding: 20px 25px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.search-group {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.search-input {
    flex: 1;
    min-width: 200px;
    padding: 10px 15px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 14px;
    transition: border-color 0.3s;
    outline: none;
}

.search-input:focus {
    border-color: #667eea;
}

.search-select {
    padding: 10px 15px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 14px;
    outline: none;
    background: #fff;
    cursor: pointer;
}

.search-select:focus {
    border-color: #667eea;
}

.search-tip {
    background: #fff;
    border-radius: 8px;
    padding: 12px 20px;
    margin-bottom: 20px;
    font-size: 14px;
    color: #666;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

/* ========== 表格 ========== */
.table-container {
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table th {
    background: #f8f9ff;
    padding: 14px 12px;
    text-align: left;
    font-size: 13px;
    font-weight: 600;
    color: #666;
    border-bottom: 2px solid #e8e8ff;
    white-space: nowrap;
}

.data-table td {
    padding: 12px;
    font-size: 14px;
    border-bottom: 1px solid #f0f0f0;
    color: #444;
}

.data-table tbody tr:hover {
    background: #f8f9ff;
}

.data-table tbody tr:last-child td {
    border-bottom: none;
}

.action-cell {
    white-space: nowrap;
    display: flex;
    gap: 5px;
}

/* ========== 状态标签 ========== */
.status-badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.status-在读 {
    background: #d4edda;
    color: #155724;
}

.status-休学 {
    background: #fff3cd;
    color: #856404;
}

.status-毕业 {
    background: #cce5ff;
    color: #004085;
}

/* ========== 分页 ========== */
.pagination {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    border-top: 1px solid #f0f0f0;
}

.page-info {
    font-size: 13px;
    color: #999;
}

.page-links {
    display: flex;
    gap: 5px;
}

.page-link {
    display: inline-block;
    padding: 6px 12px;
    border-radius: 6px;
    font-size: 13px;
    text-decoration: none;
    color: #666;
    background: #f5f5f5;
    transition: all 0.3s;
}

.page-link:hover {
    background: #e8e8ff;
    color: #667eea;
}

.page-link.active {
    background: #667eea;
    color: #fff;
}

/* ========== 空状态 ========== */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: #999;
}

.empty-state p {
    font-size: 18px;
    margin-bottom: 20px;
}

/* ========== 表单 ========== */
.form-container {
    background: #fff;
    border-radius: 12px;
    padding: 30px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.data-form {
    max-width: 900px;
}

.form-row {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
}

.form-group {
    flex: 1;
    min-width: 0;
}

.form-group.full-width {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    font-weight: 500;
    color: #555;
}

.required {
    color: #e74c3c;
}

.form-control {
    width: 100%;
    padding: 10px 14px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 14px;
    transition: border-color 0.3s;
    outline: none;
    font-family: inherit;
}

.form-control:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-control[readonly] {
    background: #f9f9f9;
    cursor: not-allowed;
}

textarea.form-control {
    resize: vertical;
}

.form-tip {
    display: block;
    margin-top: 4px;
    font-size: 12px;
}

.form-actions {
    display: flex;
    gap: 10px;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid #f0f0f0;
}

/* ========== 提示信息 ========== */
.alert {
    padding: 14px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

.alert-error {
    background: #fde8e8;
    color: #c0392b;
    border: 1px solid #f5c6cb;
}

.alert-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

/* ========== 欢迎页 ========== */
.welcome-page {
    background: #fff;
    border-radius: 16px;
    padding: 50px 40px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    margin-top: 50px;
}

.welcome-header h1 {
    font-size: 36px;
    background: linear-gradient(135deg, #667eea, #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 10px;
}

.subtitle {
    font-size: 16px;
    color: #999;
    margin-bottom: 40px;
}

.welcome-content {
    display: flex;
    justify-content: center;
    gap: 60px;
    margin-bottom: 40px;
    text-align: left;
}

.system-info, .tech-stack {
    flex: 1;
    max-width: 350px;
}

.system-info h3, .tech-stack h3 {
    font-size: 18px;
    color: #333;
    margin-bottom: 15px;
    padding-bottom: 8px;
    border-bottom: 2px solid #667eea;
}

.system-info ul, .tech-stack ul {
    list-style: none;
    padding: 0;
}

.system-info li, .tech-stack li {
    padding: 8px 0;
    font-size: 14px;
    color: #666;
}

.welcome-actions {
    display: flex;
    gap: 15px;
    justify-content: center;
}

.welcome-actions .btn {
    padding: 14px 36px;
    font-size: 16px;
}

/* ========== 错误页 ========== */
.error-page {
    background: #fff;
    border-radius: 16px;
    padding: 60px 40px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    margin-top: 80px;
}

.error-page h1 {
    font-size: 48px;
    color: #e74c3c;
    margin-bottom: 15px;
}

.error-page p {
    font-size: 16px;
    color: #666;
    margin-bottom: 10px;
}

.error-detail {
    background: #fde8e8;
    padding: 12px 20px;
    border-radius: 8px;
    margin: 15px auto;
    max-width: 600px;
    font-size: 14px;
    color: #c0392b;
}

/* ========== 响应式 ========== */
@media (max-width: 768px) {
    .form-row {
        flex-direction: column;
        gap: 15px;
    }

    .welcome-content {
        flex-direction: column;
        gap: 30px;
        align-items: center;
    }

    .navbar {
        flex-direction: column;
        gap: 10px;
    }

    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
    }

    .search-group {
        flex-direction: column;
    }

    .pagination {
        flex-direction: column;
        gap: 10px;
        text-align: center;
    }

    .page-header {
        flex-direction: column;
        gap: 10px;
        text-align: center;
    }
}