/* 全局样式 */
:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    line-height: 1.6;
}

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

/* 导航栏 */
.navbar {
    background-color: var(--bg-primary);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
}

.navbar-menu {
    display: flex;
    list-style: none;
    gap: 1.5rem;
    align-items: center;
}

.navbar-menu a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color 0.3s;
}

.navbar-menu a:hover {
    color: var(--primary-color);
}

.navbar-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
}

/* 主内容区 */
.main-content {
    padding: 2rem 0;
    min-height: calc(100vh - 200px);
}

/* 卡片 */
.card {
    background-color: var(--bg-primary);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.card-body {
    padding: 0;
}

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

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

textarea.form-control {
    min-height: 100px;
    resize: vertical;
}

select.form-control {
    cursor: pointer;
}

.form-check {
    display: flex;
    align-items: center;
    margin-bottom: 0.5rem;
}

.form-check-input {
    margin-right: 0.5rem;
    cursor: pointer;
}

/* 按钮 */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-success {
    background-color: var(--success-color);
    color: white;
}

.btn-success:hover {
    background-color: #059669;
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
}

.btn-danger:hover {
    background-color: #dc2626;
}

.btn-warning {
    background-color: var(--warning-color);
    color: white;
}

.btn-secondary {
    background-color: #6b7280;
    color: white;
}

.btn-secondary:hover {
    background-color: #4b5563;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-group {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* 表格 */
.table-responsive {
    overflow-x: auto;
}

.table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--bg-primary);
}

.table th,
.table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.table th {
    background-color: var(--bg-secondary);
    font-weight: 600;
    color: var(--text-primary);
}

.table tbody tr:hover {
    background-color: var(--bg-secondary);
}

/* 分页 */
.pagination {
    display: flex;
    justify-content: center;
    margin-top: 2rem;
}

.pagination-list {
    display: flex;
    list-style: none;
    gap: 0.5rem;
}

.pagination-list a,
.pagination-list span {
    display: block;
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    text-decoration: none;
    color: var(--text-primary);
    transition: all 0.3s;
}

.pagination-list a:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.pagination-list .active span {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* 警告框 */
.alert {
    padding: 1rem;
    border-radius: 6px;
    margin-bottom: 1rem;
}

.alert-success {
    background-color: #d1fae5;
    color: #065f46;
    border: 1px solid #a7f3d0;
}

.alert-error {
    background-color: #fee2e2;
    color: #991b1b;
    border: 1px solid #fecaca;
}

.alert-warning {
    background-color: #fef3c7;
    color: #92400e;
    border: 1px solid #fde68a;
}

.alert-info {
    background-color: #dbeafe;
    color: #1e40af;
    border: 1px solid #bfdbfe;
}

/* 徽章 */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 12px;
    white-space: nowrap;
}

.badge-primary {
    background-color: #dbeafe;
    color: #1e40af;
}

.badge-success {
    background-color: #d1fae5;
    color: #065f46;
}

.badge-danger {
    background-color: #fee2e2;
    color: #991b1b;
}

.badge-warning {
    background-color: #fef3c7;
    color: #92400e;
}

/* 统计卡片 */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: var(--shadow-md);
}

.stat-card h3 {
    font-size: 0.875rem;
    font-weight: 500;
    opacity: 0.9;
    margin-bottom: 0.5rem;
}

.stat-card .stat-value {
    font-size: 2rem;
    font-weight: bold;
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

/* 模态框 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background-color: var(--bg-primary);
    border-radius: 8px;
    max-width: 600px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 20px 25px rgba(0, 0, 0, 0.1);
}

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

.modal-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
}

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 0.5rem;
}

/* 题目显示 */
.question-item {
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 1.5rem;
    background-color: var(--bg-primary);
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 1rem;
}

.question-type {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background-color: var(--primary-color);
    color: white;
    border-radius: 4px;
    font-size: 0.875rem;
}

.question-content {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    line-height: 1.8;
}

.question-options {
    margin: 1rem 0;
}

.option-item {
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
}

.option-item:hover {
    background-color: var(--bg-secondary);
}

.option-item.selected {
    background-color: #dbeafe;
    border-color: var(--primary-color);
}

.option-item.correct {
    background-color: #d1fae5;
    border-color: var(--success-color);
}

.option-item.wrong {
    background-color: #fee2e2;
    border-color: var(--danger-color);
}

/* 页脚 */
.footer {
    background-color: var(--bg-primary);
    padding: 2rem 0;
    margin-top: 3rem;
    border-top: 1px solid var(--border-color);
    text-align: center;
    color: var(--text-secondary);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--bg-primary);
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow-md);
    }
    
    .navbar-menu.active {
        display: flex;
    }
    
    .navbar-toggle {
        display: block;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .btn-group {
        flex-direction: column;
    }
    
    .btn-group .btn {
        width: 100%;
    }
    
    .table-responsive {
        font-size: 0.875rem;
    }
    
    .table th,
    .table td {
        padding: 0.5rem;
    }
}

/* 打印样式 */
@media print {
    .navbar,
    .btn,
    .pagination,
    .modal {
        display: none !important;
    }
}

/* 工具类 */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.d-flex { display: flex; }
.justify-between { justify-content: space-between; }
.align-center { align-items: center; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }