/* ===== 全局样式 ===== */
:root {
    --primary-color: #B22222;
    --primary-hover: #8B0000;
    --secondary-color: #A9A9A9;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --background-color: #F5F5F5;
    --card-background: #ffffff;
    --text-primary: #333333;
    --text-secondary: #666666;
    --border-color: #D3D3D3;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

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

/* ===== 头部导航 ===== */
.header {
    background: var(--card-background);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.logo h1 {
    font-size: 20px;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 2px;
}

.logo .subtitle {
    font-size: 12px;
    color: var(--text-secondary);
}

.nav-menu {
    display: flex;
    gap: 8px;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    text-decoration: none;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    transition: var(--transition);
    font-size: 14px;
}

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

.nav-item.active {
    background-color: var(--primary-color);
    color: white;
}

.nav-item .icon {
    font-size: 18px;
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 3px;
    background-color: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition);
}

/* ===== 主内容区域 ===== */
.main-content {
    padding-top: 24px;
    padding-bottom: 48px;
    min-height: calc(100vh - 64px - 80px);
}

.page {
    display: none;
}

.page.active {
    display: block;
}

/* ===== 首页样式 ===== */
.hero {
    text-align: center;
    padding: 48px 20px;
    background: linear-gradient(135deg, var(--primary-color), #8B0000);
    color: white;
    border-radius: var(--radius-lg);
    margin-bottom: 32px;
}

.hero h2 {
    font-size: 32px;
    margin-bottom: 8px;
}

.hero p {
    font-size: 16px;
    opacity: 0.9;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 20px;
    margin-bottom: 32px;
}

.stat-card {
    background: var(--card-background);
    padding: 24px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
    gap: 16px;
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    font-size: 40px;
}

.stat-content h3 {
    font-size: 28px;
    color: var(--primary-color);
    margin-bottom: 4px;
}

.stat-content p {
    font-size: 14px;
    color: var(--text-secondary);
}

.quick-actions {
    background: var(--card-background);
    padding: 24px;
}

/* 简化反馈页面样式 */
.feedback-message {
    padding: 24px 0;
    color: var(--text-primary);
}

.feedback-message p {
    margin-bottom: 16px;
    font-size: 16px;

    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    margin-bottom: 32px;
}

.quick-actions h3 {
    font-size: 18px;
    margin-bottom: 16px;
}

.action-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 12px;
}

.action-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 20px;
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    font-size: 14px;
    color: var(--text-primary);
}

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

.recent-activity {
    background: var(--card-background);
    padding: 24px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.recent-activity h3 {
    font-size: 18px;
    margin-bottom: 16px;
}

.activity-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.activity-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px;
    background: var(--background-color);
    border-radius: var(--radius-md);
}

.activity-icon {
    font-size: 24px;
}

.activity-content {
    flex: 1;
}

.activity-content h4 {
    font-size: 14px;
    margin-bottom: 2px;
}

.activity-content p {
    font-size: 12px;
    color: var(--text-secondary);
}

.activity-time {
    font-size: 12px;
    color: var(--text-secondary);
}

/* ===== 页面头部 ===== */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.page-header h2 {
    font-size: 24px;
}

/* ===== 按钮样式 ===== */
.primary-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
}

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

.secondary-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--card-background);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
}

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

/* ===== 筛选器 ===== */
.filters {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
}

.filters select,
.filters input {
    padding: 10px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    background: var(--card-background);
}

.filters select {
    min-width: 160px;
}

.filters input {
    flex: 1;
    max-width: 300px;
}

/* ===== 卡片网格 ===== */
.meetings-grid,
.members-grid,
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.card {
    background: var(--card-background);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: 20px;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 12px;
}

.card-title {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 4px;
}

.card-meta {
    font-size: 12px;
    color: var(--text-secondary);
}

.card-body {
    margin-bottom: 12px;
}

.card-footer {
    display: flex;
    gap: 8px;
    padding-top: 12px;
    border-top: 1px solid var(--border-color);
}

/* ===== 标签 ===== */
.tag {
    display: inline-block;
    padding: 4px 12px;
    background: var(--background-color);
    color: var(--text-secondary);
    border-radius: 20px;
    font-size: 12px;
    margin-right: 6px;
}

.tag.primary {
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary-color);
}

.tag.success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
}

.tag.warning {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning-color);
}

/* ===== 表单样式 ===== */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 10px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    font-family: inherit;
    transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

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

/* ===== 底部 ===== */
.footer {
    background: var(--card-background);
    border-top: 1px solid var(--border-color);
    padding: 20px 0;
    text-align: center;
}

.footer p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

/* ===== 模态框 ===== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--card-background);
    border-radius: var(--radius-lg);
    padding: 24px;
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    transform: scale(0.9);
    transition: var(--transition);
}

.modal-overlay.active .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.modal-header h3 {
    font-size: 20px;
}

.modal-close {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-secondary);
    transition: var(--transition);
}

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

/* ===== Toast提示 ===== */
.toast {
    position: fixed;
    top: 80px;
    right: 20px;
    background: var(--card-background);
    border-radius: var(--radius-md);
    padding: 16px 24px;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 12px;
    z-index: 2000;
    animation: slideIn 0.3s ease;
}

.toast.success {
    border-left: 4px solid var(--success-color);
}

.toast.error {
    border-left: 4px solid var(--danger-color);
}

.toast.warning {
    border-left: 4px solid var(--warning-color);
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ===== 学期总结标签页 ===== */
.summary-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
    overflow-x: auto;
    padding-bottom: 8px;
}

.tab-btn {
    padding: 10px 20px;
    background: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    font-size: 14px;
    white-space: nowrap;
}

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

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

/* ===== 资源分类按钮 ===== */
.resource-categories {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
    overflow-x: auto;
    padding-bottom: 8px;
}

.category-btn {
    padding: 10px 20px;
    background: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    font-size: 14px;
    white-space: nowrap;
}

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

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

/* ===== 成员筛选器 ===== */
.member-filters {
    margin-bottom: 24px;
}

.member-filters select {
    padding: 10px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    background: var(--card-background);
    min-width: 160px;
}

/* ===== 反馈表单容器 ===== */
.feedback-form-container {
    background: var(--card-background);
    padding: 32px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    max-width: 600px;
    margin-bottom: 32px;
}

.feedback-history {
    background: var(--card-background);
    padding: 24px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.feedback-history h3 {
    font-size: 18px;
    margin-bottom: 16px;
}

.feedback-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.feedback-item {
    padding: 16px;
    background: var(--background-color);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--primary-color);
}

.feedback-item h4 {
    font-size: 14px;
    margin-bottom: 8px;
}

.feedback-item p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.feedback-item .meta {
    font-size: 12px;
    color: var(--text-secondary);
}

/* ===== 空状态 ===== */
.empty-state {
    text-align: center;
    padding: 48px 20px;
    color: var(--text-secondary);
}

.empty-state .icon {
    font-size: 48px;
    margin-bottom: 16px;
}

.empty-state p {
    font-size: 16px;
}

/* ===== 加载状态 ===== */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 48px 20px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* ===== 文件上传 ===== */
.file-upload-area {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-md);
    padding: 32px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
}

.file-upload-area:hover {
    border-color: var(--primary-color);
    background: rgba(37, 99, 235, 0.05);
}

.file-upload-area.dragover {
    border-color: var(--primary-color);
    background: rgba(37, 99, 235, 0.1);
}

.file-upload-area input[type="file"] {
    display: none;
}

.file-upload-area .icon {
    font-size: 48px;
    margin-bottom: 12px;
}

.file-upload-area p {
    color: var(--text-secondary);
    font-size: 14px;
}