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

:root {
    --primary-color: #409EFF;
    --success-color: #67C23A;
    --warning-color: #E6A23C;
    --danger-color: #F56C6C;
    --info-color: #909399;
    --bg-color: #f5f7fa;
    --card-bg: #ffffff;
    --text-primary: #303133;
    --text-regular: #606266;
    --text-secondary: #909399;
    --border-color: #DCDFE6;
}

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

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 导航栏 */
.navbar {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: bold;
    color: white;
    text-decoration: none;
}

.navbar-nav {
    display: flex;
    gap: 2rem;
    list-style: none;
    align-items: center;
}

.nav-item {
    /* 不设置display，让元素成为flex item */
}

.nav-item.hidden {
    display: none !important;
}

.navbar-nav a {
    color: white;
    text-decoration: none;
    transition: opacity 0.3s;
}

.navbar-nav a:hover {
    opacity: 0.8;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* 按钮 */
.btn {
    padding: 0.5rem 1.5rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

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

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

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

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

.btn-secondary {
    background-color: #6c757d;
    color: white;
}

.btn:hover {
    opacity: 0.85;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

/* 卡片 */
.card {
    background: var(--card-bg);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    transition: all 0.3s;
}

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

.card-header {
    font-size: 1.2rem;
    font-weight: bold;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--border-color);
}

/* 表单 */
.form-group {
    margin-bottom: 1.5rem;
}

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

.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 14px;
    transition: border-color 0.3s;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(64, 158, 255, 0.1);
}

select.form-control {
    cursor: pointer;
}

/* 网格系统 */
.row {
    display: flex;
    flex-wrap: wrap;
    margin: 0 -10px;
}

.col {
    flex: 1;
    padding: 0 10px;
}

.col-2 {
    flex: 0 0 50%;
    padding: 0 10px;
}

.col-3 {
    flex: 0 0 33.333%;
    padding: 0 10px;
}

.col-4 {
    flex: 0 0 25%;
    padding: 0 10px;
}

/* 表格 */
.table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border-radius: 8px;
    overflow: hidden;
}

.table thead {
    background-color: #f5f7fa;
}

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

.table tbody tr:hover {
    background-color: #f5f7fa;
}

/* 学习计划表 */
.schedule-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 1rem;
    margin-top: 2rem;
}

.day-column {
    background: var(--card-bg);
    border-radius: 8px;
    padding: 1rem;
    min-height: 500px;
}

.day-header {
    font-weight: bold;
    text-align: center;
    padding-bottom: 0.75rem;
    margin-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
}

.plan-item {
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    border-radius: 6px;
    color: white;
    font-size: 0.875rem;
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

.plan-item-title {
    font-weight: bold;
    margin-bottom: 0.25rem;
}

.plan-item-time {
    font-size: 0.75rem;
    opacity: 0.9;
}

.plan-item-desc {
    font-size: 0.75rem;
    margin-top: 0.25rem;
    opacity: 0.85;
}

/* 模态框 */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    animation: fadeIn 0.3s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    max-width: 600px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideDown 0.3s;
}

@keyframes slideDown {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.close {
    font-size: 2rem;
    font-weight: bold;
    color: var(--text-secondary);
    cursor: pointer;
    border: none;
    background: none;
}

.close:hover {
    color: var(--text-primary);
}

/* 加载动画 */
.loading {
    text-align: center;
    padding: 2rem;
}

.spinner {
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 0 auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 提示消息 */
.alert {
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
}

.alert-success {
    background-color: #f0f9ff;
    color: var(--success-color);
    border: 1px solid var(--success-color);
}

.alert-error {
    background-color: #fef0f0;
    color: var(--danger-color);
    border: 1px solid var(--danger-color);
}

.alert-warning {
    background-color: #fdf6ec;
    color: var(--warning-color);
    border: 1px solid var(--warning-color);
}

/* 响应式设计 */
@media (max-width: 992px) {
    .schedule-grid {
        grid-template-columns: repeat(4, 1fr);
    }
    
    .col-3, .col-4 {
        flex: 0 0 50%;
    }
}

@media (max-width: 768px) {
    .navbar .container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .navbar-nav {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .schedule-grid {
        grid-template-columns: 1fr;
    }
    
    .row {
        flex-direction: column;
    }
    
    .col, .col-2, .col-3, .col-4 {
        flex: 0 0 100%;
    }
}

/* 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; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.p-1 { padding: 0.5rem; }
.p-2 { padding: 1rem; }
.p-3 { padding: 1.5rem; }
.p-4 { padding: 2rem; }

.hidden {
    display: none !important;
}

.flex {
    display: flex;
}

.justify-between {
    justify-content: space-between;
}

.items-center {
    align-items: center;
}

.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }