/* 主色调 - 绿色主题 */
:root {
    --primary-color: #28a745;
    --primary-dark: #1e7e34;
    --primary-light: #48c764;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --warning-color: #ffc107;
    --danger-color: #dc3545;
    --info-color: #17a2b8;
    --bg-light: #f8f9fa;
}

/* 全局样式 */
body {
    background-color: var(--bg-light);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

/* 导航栏 */
.navbar {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%) !important;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.navbar-brand {
    font-weight: 600;
    font-size: 1.25rem;
}

/* 导航菜单 */
.nav-menu {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    padding: 0.75rem 0;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-menu .nav-link {
    color: rgba(255, 255, 255, 0.9);
    padding: 0.5rem 0.875rem;
    border-radius: 8px;
    margin: 0 3px;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.nav-menu .nav-link:hover {
    color: #fff;
    background-color: rgba(255, 255, 255, 0.15);
    transform: translateY(-1px);
}

.nav-menu .nav-link.active {
    color: #fff;
    background-color: rgba(255, 255, 255, 0.25);
    font-weight: 500;
}

/* 卡片 */
.card {
    border: none;
    border-radius: 12px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    transition: box-shadow 0.3s ease;
}

.card:hover {
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.12);
}

.card-header {
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    font-weight: 600;
}

/* 标签页 */
.nav-tabs {
    border-bottom: 2px solid #dee2e6;
}

.nav-tabs .nav-link {
    border: none;
    border-bottom: 3px solid transparent;
    color: var(--secondary-color);
    font-weight: 500;
    padding: 12px 24px;
    transition: all 0.3s ease;
}

.nav-tabs .nav-link:hover {
    border-color: transparent;
    color: var(--primary-color);
}

.nav-tabs .nav-link.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
    background-color: transparent;
}

/* 表格 */
.table {
    margin-bottom: 0;
}

.table thead th {
    border-top: none;
    border-bottom: 2px solid var(--primary-light);
    color: var(--secondary-color);
    font-weight: 600;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.table tbody tr {
    transition: background-color 0.2s ease;
}

.table tbody tr:hover {
    background-color: rgba(40, 167, 69, 0.05);
}

/* 按钮 */
.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    border: none;
    transition: all 0.3s ease;
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-color) 100%);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(40, 167, 69, 0.3);
}

.btn-outline-primary {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

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

/* 登录页 */
.login-page {
    min-height: 100vh;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
}

.login-container {
    width: 100%;
    max-width: 400px;
    padding: 20px;
}

.login-card {
    background: white;
    border-radius: 16px;
    padding: 40px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
}

.login-header {
    text-align: center;
    margin-bottom: 30px;
}

.login-header h2 {
    color: var(--primary-color);
    font-weight: 700;
    margin-bottom: 8px;
}

.login-card .form-control {
    border-radius: 8px;
    padding: 12px 16px;
    border: 1px solid #e0e0e0;
    transition: all 0.3s ease;
}

.login-card .form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(40, 167, 69, 0.15);
}

.login-card .btn-primary {
    padding: 12px;
    font-weight: 600;
    font-size: 1rem;
    border-radius: 8px;
}

/* 徽章 */
.badge {
    font-weight: 500;
    padding: 6px 10px;
    border-radius: 6px;
}

/* 列表组 */
.list-group-item {
    border-left: none;
    border-right: none;
    padding: 12px 16px;
}

.list-group-item:first-child {
    border-top: none;
    border-top-left-radius: 0;
    border-top-right-radius: 0;
}

.list-group-item:last-child {
    border-bottom: none;
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
}

.list-group-item-action:hover {
    background-color: rgba(40, 167, 69, 0.1);
}

.list-group-item.active {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}

/* 关联项 */
.relation-item {
    transition: all 0.2s ease;
}

.relation-item:hover {
    background-color: #e9ecef !important;
}

/* 模态框 */
.modal-content {
    border: none;
    border-radius: 12px;
}

.modal-header {
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.modal-footer {
    border-top: 1px solid rgba(0, 0, 0, 0.05);
}

/* Toast */
.toast {
    border: none;
    border-radius: 8px;
    min-width: 250px;
}

/* 响应式 */
@media (max-width: 768px) {
    .login-card {
        padding: 30px 20px;
    }
    
    .nav-tabs .nav-link {
        padding: 10px 16px;
        font-size: 0.9rem;
    }
    
    #assignmentTab .row {
        flex-direction: column;
    }
    
    #assignmentTab .col-md-3,
    #assignmentTab .col-md-6 {
        width: 100%;
        margin-bottom: 16px;
    }
    
    .table-responsive {
        font-size: 0.85rem;
    }
}

/* 加载动画 */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid rgba(40, 167, 69, 0.3);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: var(--secondary-color);
}

.empty-state i {
    font-size: 48px;
    margin-bottom: 16px;
    opacity: 0.5;
}

/* 滚动条美化 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #a1a1a1;
}