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

:root {
    --primary-color: #5B9BD5;
    --primary-hover: #4A8BC4;
    --primary-light: #E8F4FC;
    --secondary-color: #7EB8E8;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --bg-color: #F0F7FC;
    --card-bg: #ffffff;
    --text-primary: #2C3E50;
    --text-secondary: #7F8C9A;
    --border-color: #D4E5F7;
    --shadow: 0 4px 6px -1px rgba(91, 155, 213, 0.1), 0 2px 4px -1px rgba(91, 155, 213, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(91, 155, 213, 0.1), 0 4px 6px -2px rgba(91, 155, 213, 0.05);
}

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;
}

/* 导航栏 */
.navbar {
    background: linear-gradient(135deg, #E8F4FC 0%, #B8D4E8 100%);
    padding: 0 2rem;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--primary-color);
    font-size: 1.25rem;
    font-weight: 600;
}

.nav-brand i {
    font-size: 1.5rem;
}

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

.nav-menu a {
    color: var(--text-primary);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-menu a:hover,
.nav-menu a.active {
    background: var(--primary-color);
    color: white;
}

/* 返回主页按钮 */
.back-home-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 0.5rem;
    font-weight: 500;
    transition: all 0.3s ease;
    border: none;
}

.back-home-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

/* 主容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 84px 20px 40px;
}

/* 页面切换 */
.page {
    display: none;
    animation: fadeIn 0.3s ease;
}

.page.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* 页面头部 */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.page-header h1 {
    font-size: 1.875rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.page-header h1 i {
    color: var(--primary-color);
}

/* 搜索框 */
.search-box {
    display: flex;
    gap: 0.5rem;
}

.search-box input {
    padding: 0.625rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 0.875rem;
    width: 280px;
    transition: all 0.3s ease;
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.search-box button {
    padding: 0.625rem 1rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.search-box button:hover {
    background: var(--primary-hover);
}

/* 筛选区域 */
.filter-section {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.filter-label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
    white-space: nowrap;
}

/* 科目筛选 */
.subject-filter {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.subject-btn {
    padding: 0.5rem 1rem;
    border: 2px solid var(--border-color);
    background: white;
    border-radius: 2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.subject-btn:hover,
.subject-btn.active {
    background: linear-gradient(135deg, #5B9BD5 0%, #7EB8E8 100%);
    border-color: #5B9BD5;
    color: white;
}

/* 分类筛选 */
.category-filter {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.category-btn {
    padding: 0.375rem 0.75rem;
    border: 2px solid var(--border-color);
    background: white;
    border-radius: 2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.category-btn:hover,
.category-btn.active {
    background: linear-gradient(135deg, #5B9BD5 0%, #7EB8E8 100%);
    border-color: #5B9BD5;
    color: white;
}

/* 资料网格 */
.materials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.material-card {
    background: var(--card-bg);
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

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

.material-icon {
    width: 56px;
    height: 56px;
    border-radius: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.material-icon.ppt { background: #fef3c7; color: #d97706; }
.material-icon.pdf { background: #fee2e2; color: #dc2626; }
.material-icon.doc { background: #dbeafe; color: #2563eb; }
.material-icon.zip { background: #d1fae5; color: #059669; }
.material-icon.default { background: #e0e7ff; color: #4f46e5; }

.material-card h3 {
    font-size: 1.125rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.material-card .category {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--bg-color);
    border-radius: 1rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.material-card .desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.5;
}

.material-card .meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.material-card .actions {
    display: flex;
    gap: 0.5rem;
}

.btn {
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

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

.btn-secondary {
    background: var(--bg-color);
    color: var(--text-primary);
}

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

/* 上传区域 */
.upload-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

@media (max-width: 768px) {
    .upload-section {
        grid-template-columns: 1fr;
    }
}

/* 作业提交布局 */
.homework-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

@media (max-width: 900px) {
    .homework-layout {
        grid-template-columns: 1fr;
    }
}

.upload-card {
    background: var(--card-bg);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.upload-card h2 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.form-hint {
    margin-top: 0.5rem;
    padding: 0.75rem 1rem;
    background: var(--bg-color);
    border-radius: 0.5rem;
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.form-hint i {
    color: var(--primary-color);
    margin-right: 0.25rem;
}

/* 提交记录卡片 */
.submission-history-card {
    background: var(--card-bg);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.submission-history-card h2 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.history-empty {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.history-empty i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.3;
}

.history-empty p {
    font-size: 0.9rem;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    max-height: 400px;
    overflow-y: auto;
}

.history-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--bg-color);
    border-radius: 0.75rem;
    border: 1px solid var(--border-color);
    transition: all 0.2s;
}

.history-item:hover {
    border-color: var(--primary-color);
}

.history-item-info {
    flex: 1;
    min-width: 0;
}

.history-item-project {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.history-item-file {
    font-size: 0.8rem;
    color: var(--text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.history-item-time {
    font-size: 0.75rem;
    color: var(--text-light);
    margin-top: 0.25rem;
}

.history-item-status {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.25rem;
    margin-left: 1rem;
}

.status-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

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

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

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

.view-btn {
    padding: 0.25rem 0.5rem;
    font-size: 0.7rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.25rem;
    cursor: pointer;
    transition: all 0.2s;
}

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

.view-btn:disabled {
    background: var(--border-color);
    cursor: not-allowed;
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 0.875rem;
    transition: all 0.3s ease;
    font-family: inherit;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.file-upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 0.75rem;
    padding: 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.file-upload-area:hover {
    border-color: var(--primary-color);
    background: var(--bg-color);
}

.file-upload-area.dragover {
    border-color: var(--primary-color);
    background: #e0e7ff;
}

.upload-placeholder i {
    font-size: 3rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.upload-placeholder p {
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.upload-placeholder span {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.file-info {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--bg-color);
    border-radius: 0.5rem;
    margin-top: 0.75rem;
}

.file-info i {
    color: var(--primary-color);
}

.remove-file {
    margin-left: auto;
    background: none;
    border: none;
    color: var(--danger-color);
    cursor: pointer;
    padding: 0.25rem;
}

.submit-btn {
    width: 100%;
    padding: 0.875rem;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.4);
}

.submit-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* 历史记录 */
.upload-history {
    background: var(--card-bg);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.upload-history h2 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.history-list {
    max-height: 500px;
    overflow-y: auto;
}

.history-item {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.history-item:last-child {
    border-bottom: none;
}

.history-item .icon {
    width: 40px;
    height: 40px;
    background: var(--bg-color);
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
}

.history-item .info {
    flex: 1;
}

.history-item .info h4 {
    font-size: 0.875rem;
    margin-bottom: 0.25rem;
}

.history-item .info p {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.history-item .status {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
}

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

.status-pending {
    background: #fef3c7;
    color: #92400e;
}

.status-active {
    background: #dbeafe;
    color: #1e40af;
}

.status-expired {
    background: #fee2e2;
    color: #991b1b;
}

/* 管理员登录 */
.login-modal {
    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: 2000;
}

.login-box {
    background: white;
    padding: 2.5rem;
    border-radius: 1rem;
    width: 100%;
    max-width: 400px;
    box-shadow: var(--shadow-lg);
}

.login-box h2 {
    text-align: center;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.login-box .hint {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 1rem;
}

/* 管理员界面 */
.admin-content {
    animation: fadeIn 0.3s ease;
}

.admin-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-secondary);
    border-radius: 0.5rem;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.tab-btn:hover,
.tab-btn.active {
    background: var(--bg-color);
    color: var(--primary-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

.logout-btn {
    padding: 0.5rem 1rem;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* 数据表格 */
.data-table {
    background: var(--card-bg);
    border-radius: 1rem;
    overflow: hidden;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

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

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

.data-table th {
    background: var(--bg-color);
    font-weight: 600;
    font-size: 0.875rem;
}

.data-table td {
    font-size: 0.875rem;
}

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

.data-table .actions {
    display: flex;
    gap: 0.5rem;
}

.data-table .btn-sm {
    padding: 0.375rem 0.75rem;
    font-size: 0.75rem;
}

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

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

/* Toast 提示 */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    padding: 1rem 1.5rem;
    background: var(--text-primary);
    color: white;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-lg);
    transform: translateX(400px);
    transition: transform 0.3s ease;
    z-index: 3000;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.toast.show {
    transform: translateX(0);
}

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

.toast.error {
    background: var(--danger-color);
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
    grid-column: 1 / -1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 300px;
}

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

.empty-state p {
    font-size: 1rem;
}

/* 加载动画 */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

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

/* 自动完成下拉框样式 */
.autocomplete-container {
    position: relative;
    width: 100%;
}

.autocomplete-list {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: white;
    border: 2px solid var(--border-color);
    border-top: none;
    border-radius: 0 0 0.5rem 0.5rem;
    max-height: 200px;
    overflow-y: auto;
    z-index: 100;
    display: none;
    box-shadow: var(--shadow-lg);
}

.autocomplete-list.show {
    display: block;
}

.autocomplete-item {
    padding: 0.75rem 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.autocomplete-item:last-child {
    border-bottom: none;
}

.autocomplete-item:hover,
.autocomplete-item.active {
    background: var(--bg-color);
    color: var(--primary-color);
}

.autocomplete-item .student-id {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.autocomplete-item:hover .student-id,
.autocomplete-item.active .student-id {
    color: var(--primary-color);
}

.autocomplete-no-result {
    padding: 0.75rem 1rem;
    color: var(--text-secondary);
    text-align: center;
    font-size: 0.875rem;
}

/* 输入框只读样式 */
input[readonly] {
    background: var(--bg-color);
    cursor: not-allowed;
}

/* 学生名单管理样式 */
.students-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.add-method-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

.method-btn {
    padding: 0.75rem 1.5rem;
    background: white;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-secondary);
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.add-content {
    display: none;
    animation: fadeIn 0.3s ease;
}

.add-content.active {
    display: block;
}

/* 提交状态弹窗 */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    padding: 1rem;
}

.modal-content {
    background: white;
    border-radius: 1rem;
    width: 100%;
    max-width: 600px;
    max-height: 80vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
}

.modal-header h3 {
    margin: 0;
    font-size: 1.125rem;
}

.modal-close {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s;
}

.modal-close:hover {
    background: rgba(255, 255, 255, 0.3);
}

.modal-body {
    padding: 1.5rem;
    overflow-y: auto;
}

.status-summary {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.summary-item {
    flex: 1;
    text-align: center;
    padding: 1rem;
    border-radius: 0.75rem;
    background: var(--bg-color);
}

.summary-item .count {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.summary-item .label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.summary-item.submitted-count .count {
    color: var(--success-color);
}

.summary-item.not-submitted-count .count {
    color: var(--danger-color);
}

.status-sections {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.status-section h4 {
    margin: 0 0 0.75rem;
    font-size: 0.875rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.status-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.status-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 0.75rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
}

.status-item.submitted {
    background: #d1fae5;
    color: #065f46;
}

.status-item.not-submitted {
    background: #fee2e2;
    color: #991b1b;
}

.status-item .name {
    font-weight: 500;
}

.status-item .id {
    opacity: 0.8;
    font-size: 0.75rem;
}

.status-item .time {
    opacity: 0.6;
    font-size: 0.7rem;
}

.empty-text {
    color: var(--text-secondary);
    font-size: 0.875rem;
    text-align: center;
    padding: 1rem;
}

/* 响应式 */
@media (max-width: 768px) {
    .navbar {
        padding: 0 0.5rem;
        height: 56px;
        flex-wrap: nowrap;
    }

    .nav-brand {
        font-size: 0.875rem;
        gap: 0.25rem;
    }

    .nav-brand span:first-child {
        font-size: 1.1rem !important;
        margin-right: 4px !important;
    }

    .nav-menu {
        gap: 0.25rem;
        flex-shrink: 1;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
        -ms-overflow-style: none;
        padding-bottom: 4px;
    }

    .nav-menu::-webkit-scrollbar {
        display: none;
    }

    .nav-menu a {
        padding: 0.4rem 0.6rem;
        font-size: 0.75rem;
        gap: 0.3rem;
        white-space: nowrap;
        flex-shrink: 0;
        min-width: auto;
    }

    .nav-menu a i {
        font-size: 0.8rem;
    }

    .back-home-btn {
        padding: 0.4rem 0.6rem;
        font-size: 0.75rem;
        gap: 0.3rem;
        white-space: nowrap;
        flex-shrink: 0;
    }

    .back-home-btn i {
        font-size: 0.8rem;
    }

    .container {
        padding: 74px 0.75rem 20px;
    }

    .page-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .page-header h1 {
        font-size: 1.25rem;
    }

    .search-box {
        width: 100%;
    }

    .search-box input {
        width: 100%;
        font-size: 0.875rem;
    }

    /* 筛选区域移动端适配 */
    .filter-section {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .filter-label {
        font-size: 0.875rem;
    }

    .subject-filter,
    .category-filter {
        width: 100%;
        overflow-x: auto;
        flex-wrap: nowrap;
        padding-bottom: 0.5rem;
        -webkit-overflow-scrolling: touch;
    }

    .subject-btn,
    .category-btn {
        padding: 0.375rem 0.75rem;
        font-size: 0.75rem;
        white-space: nowrap;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .materials-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .material-card {
        padding: 1rem;
    }

    .admin-tabs {
        flex-wrap: wrap;
    }

    .data-table {
        overflow-x: auto;
    }

    /* 作业提交表单移动端适配 */
    .upload-section {
        padding: 1rem;
    }

    .drop-zone {
        padding: 2rem 1rem;
    }

    .drop-zone i {
        font-size: 2rem;
    }

    /* 管理后台移动端适配 */
    .admin-container {
        padding: 1rem;
    }

    .tab-btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.75rem;
    }
}

/* 图片转PDF功能样式 */
.img2pdf-tips {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.tip-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: linear-gradient(135deg, #d1fae5 0%, #a7f3d0 100%);
    color: #065f46;
    border-radius: 2rem;
    font-size: 0.875rem;
    font-weight: 500;
}

.img2pdf-container {
    background: var(--card-bg);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.img2pdf-upload-zone {
    border: 3px dashed var(--border-color);
    border-radius: 1rem;
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--bg-color);
}

.img2pdf-upload-zone:hover {
    border-color: var(--primary-color);
    background: var(--primary-light);
}

.img2pdf-upload-zone.dragover {
    border-color: var(--primary-color);
    background: var(--primary-light);
    transform: scale(1.02);
}

.img2pdf-upload-zone .upload-icon {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.img2pdf-upload-zone .upload-text {
    font-size: 1.125rem;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.img2pdf-upload-zone .upload-hint {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.img2pdf-preview-section {
    margin-top: 2rem;
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.preview-header h3 {
    font-size: 1rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.preview-count {
    font-weight: normal;
    color: var(--text-secondary);
}

.preview-info {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.drag-tip {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.img2pdf-preview-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 1rem;
}

.preview-item {
    position: relative;
    border-radius: 0.75rem;
    overflow: hidden;
    box-shadow: var(--shadow);
    cursor: grab;
    transition: all 0.2s ease;
    background: var(--bg-color);
    aspect-ratio: 1;
}

.preview-item:active {
    cursor: grabbing;
}

.preview-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.preview-item.sortable-ghost {
    opacity: 0.4;
}

.preview-item.sortable-chosen {
    box-shadow: 0 0 0 3px var(--primary-color);
}

.preview-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.preview-item .item-index {
    position: absolute;
    bottom: 0.375rem;
    left: 0.375rem;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 0.125rem 0.5rem;
    border-radius: 0.25rem;
    font-size: 0.75rem;
    font-weight: 600;
}

.preview-item .item-delete {
    position: absolute;
    top: 0.375rem;
    right: 0.375rem;
    width: 1.5rem;
    height: 1.5rem;
    border-radius: 50%;
    background: rgba(239, 68, 68, 0.9);
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    opacity: 0;
    transition: opacity 0.2s;
}

.preview-item:hover .item-delete {
    opacity: 1;
}

.preview-item .item-delete:hover {
    background: var(--danger-color);
}

.img2pdf-actions {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.img2pdf-progress {
    margin-top: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.progress-bar {
    flex: 1;
    height: 0.5rem;
    background: var(--bg-color);
    border-radius: 0.25rem;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    width: 0%;
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
    min-width: 3rem;
    text-align: right;
}

/* 图片转PDF移动端适配 */
@media (max-width: 768px) {
    .img2pdf-tips {
        display: none;
    }

    .img2pdf-container {
        padding: 1rem;
    }

    .img2pdf-upload-zone {
        padding: 2rem 1rem;
    }

    .img2pdf-upload-zone .upload-icon {
        font-size: 2.5rem;
    }

    .img2pdf-upload-zone .upload-text {
        font-size: 0.9rem;
    }

    .img2pdf-upload-zone .upload-hint {
        font-size: 0.75rem;
    }

    .preview-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.25rem;
    }

    .preview-header h3 {
        font-size: 0.9rem;
    }

    .img2pdf-preview-list {
        grid-template-columns: repeat(3, 1fr);
        gap: 0.5rem;
    }

    .preview-item .item-delete {
        opacity: 1;
        width: 1.25rem;
        height: 1.25rem;
        font-size: 0.625rem;
    }

    .preview-item .item-index {
        font-size: 0.625rem;
        padding: 0.125rem 0.375rem;
    }

    .img2pdf-actions {
        flex-direction: column;
        gap: 0.5rem;
    }

    .img2pdf-actions .btn {
        width: 100%;
        justify-content: center;
    }
}