/**
 * Past Paper Search - 样式表 v2.0
 * 响应式设计 + 多选功能
 */

/* ============================================
   CSS变量 - 主题配置
   ============================================ */
:root {
    --pps-primary: #2563eb;
    --pps-primary-hover: #1d4ed8;
    --pps-primary-light: #dbeafe;
    --pps-secondary: #64748b;
    --pps-success: #10b981;
    --pps-success-light: #d1fae5;
    --pps-warning: #f59e0b;
    --pps-warning-light: #fef3c7;
    --pps-danger: #ef4444;
    --pps-danger-light: #fee2e2;
    --pps-purple: #8b5cf6;
    --pps-purple-light: #ede9fe;
    --pps-pink: #ec4899;
    --pps-pink-light: #fce7f3;
    
    --pps-bg: #f8fafc;
    --pps-bg-card: #ffffff;
    --pps-border: #e2e8f0;
    --pps-text: #1e293b;
    --pps-text-muted: #64748b;
    --pps-text-light: #94a3b8;
    
    --pps-shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --pps-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --pps-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    
    --pps-radius-sm: 6px;
    --pps-radius: 10px;
    --pps-radius-lg: 16px;
    
    --pps-transition: all 0.2s ease;
}

/* ============================================
   基础容器
   ============================================ */
.pps-container {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    max-width: 1200px;
    margin: 0 auto;
    padding: 24px;
    background: var(--pps-bg);
    border-radius: var(--pps-radius-lg);
    box-sizing: border-box;
}

.pps-container * {
    box-sizing: border-box;
}

/* ============================================
   选项卡
   ============================================ */
.pps-tabs {
    display: flex;
    gap: 4px;
    margin-bottom: 20px;
    border-bottom: 2px solid var(--pps-border);
    padding-bottom: 0;
}

.pps-tab {
    padding: 12px 20px;
    font-size: 14px;
    font-weight: 600;
    color: var(--pps-text-muted);
    background: transparent;
    border: none;
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
    cursor: pointer;
    transition: var(--pps-transition);
    white-space: nowrap;
}

.pps-tab:hover {
    color: var(--pps-primary);
}

.pps-tab.active {
    color: var(--pps-primary);
    border-bottom-color: var(--pps-primary);
}

.pps-tab-panel {
    display: none;
}

.pps-tab-panel.active {
    display: block;
}

/* ============================================
   下载历史
   ============================================ */
.pps-history-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
}

.pps-history-header h3 {
    margin: 0;
    font-size: 18px;
    color: var(--pps-text);
}

.pps-btn-small {
    padding: 8px 16px;
    font-size: 13px;
    color: var(--pps-text-muted);
    background: var(--pps-bg-card);
    border: 1px solid var(--pps-border);
    border-radius: var(--pps-radius-sm);
    cursor: pointer;
    transition: var(--pps-transition);
}

.pps-btn-small:hover {
    color: var(--pps-danger);
    border-color: var(--pps-danger);
}

/* ============================================
   使用指南
   ============================================ */
.pps-guide {
    background: var(--pps-bg-card);
    padding: 24px;
    border-radius: var(--pps-radius);
    border: 1px solid var(--pps-border);
}

.pps-guide h3 {
    margin: 0 0 16px;
    font-size: 18px;
    color: var(--pps-text);
}

.pps-guide-content {
    font-size: 14px;
    line-height: 1.8;
    color: var(--pps-text-muted);
}

.pps-guide-content p {
    margin: 0 0 12px;
}

.pps-guide-content p:last-child {
    margin-bottom: 0;
}

.pps-guide-content strong {
    color: var(--pps-text);
}

/* ============================================
   搜索栏
   ============================================ */
.pps-search-bar {
    display: flex;
    gap: 12px;
    margin-bottom: 20px;
}

.pps-search-bar input {
    flex: 1;
    min-width: 0;
    padding: 14px 18px;
    font-size: 16px;
    border: 2px solid var(--pps-border);
    border-radius: var(--pps-radius);
    outline: none;
    transition: var(--pps-transition);
    background: var(--pps-bg-card);
    color: var(--pps-text);
}

.pps-search-bar input::placeholder {
    color: var(--pps-text-light);
}

.pps-search-bar input:focus {
    border-color: var(--pps-primary);
    box-shadow: 0 0 0 3px var(--pps-primary-light);
}

.pps-search-bar button {
    flex-shrink: 0;
    padding: 14px 28px;
    font-size: 16px;
    font-weight: 600;
    color: #fff;
    background: var(--pps-primary);
    border: none;
    border-radius: var(--pps-radius);
    cursor: pointer;
    transition: var(--pps-transition);
    white-space: nowrap;
}

.pps-search-bar button:hover {
    background: var(--pps-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--pps-shadow);
}

.pps-search-bar button:active {
    transform: translateY(0);
}

/* ============================================
   筛选器区域
   ============================================ */
.pps-filters {
    background: var(--pps-bg-card);
    padding: 20px;
    border-radius: var(--pps-radius);
    margin-bottom: 20px;
    box-shadow: var(--pps-shadow-sm);
    border: 1px solid var(--pps-border);
}

.pps-filter-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-bottom: 16px;
}

.pps-filter-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    min-width: 0;
}

.pps-filter-group label {
    font-size: 12px;
    font-weight: 600;
    color: var(--pps-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.pps-filter-group select {
    width: 100%;
    padding: 10px 32px 10px 12px;
    font-size: 14px;
    border: 2px solid var(--pps-border);
    border-radius: var(--pps-radius-sm);
    background: var(--pps-bg-card) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2364748b' d='M6 8L1 3h10z'/%3E%3C/svg%3E") no-repeat right 12px center;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    cursor: pointer;
    outline: none;
    transition: var(--pps-transition);
    color: var(--pps-text);
}

.pps-filter-group select:focus {
    border-color: var(--pps-primary);
}

.pps-filter-actions {
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

.pps-filter-actions button {
    padding: 10px 20px;
    font-size: 14px;
    font-weight: 500;
    color: var(--pps-text-muted);
    background: transparent;
    border: 2px solid var(--pps-border);
    border-radius: var(--pps-radius-sm);
    cursor: pointer;
    transition: var(--pps-transition);
}

.pps-filter-actions button:hover {
    color: var(--pps-primary);
    border-color: var(--pps-primary);
    background: var(--pps-primary-light);
}

/* ============================================
   批量操作工具栏
   ============================================ */
.pps-batch-toolbar {
    display: none;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 16px 20px;
    background: linear-gradient(135deg, var(--pps-primary) 0%, var(--pps-primary-hover) 100%);
    border-radius: var(--pps-radius);
    margin-bottom: 20px;
    color: #fff;
    box-shadow: var(--pps-shadow);
    flex-wrap: wrap;
}

.pps-batch-toolbar.active {
    display: flex;
}

.pps-batch-info {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}

.pps-batch-count {
    font-size: 15px;
    font-weight: 600;
}

.pps-batch-count strong {
    font-size: 20px;
    margin-right: 4px;
}

.pps-batch-actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.pps-batch-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    font-size: 14px;
    font-weight: 600;
    color: var(--pps-primary);
    background: #fff;
    border: none;
    border-radius: var(--pps-radius-sm);
    cursor: pointer;
    transition: var(--pps-transition);
    white-space: nowrap;
}

.pps-batch-btn:hover {
    background: var(--pps-primary-light);
    transform: translateY(-1px);
}

.pps-batch-btn.pps-btn-clear {
    color: #fff;
    background: rgba(255, 255, 255, 0.2);
}

.pps-batch-btn.pps-btn-clear:hover {
    background: rgba(255, 255, 255, 0.3);
}

.pps-batch-btn svg {
    width: 18px;
    height: 18px;
}

/* ============================================
   统计信息 + 全选控制
   ============================================ */
.pps-stats-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 14px 18px;
    background: var(--pps-primary-light);
    border-radius: var(--pps-radius-sm);
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.pps-stats {
    font-size: 14px;
    color: var(--pps-primary);
    display: flex;
    align-items: center;
    gap: 6px;
}

.pps-stats #pps-total-count {
    font-weight: 700;
    font-size: 18px;
}

.pps-select-all-wrap {
    display: flex;
    align-items: center;
    gap: 8px;
}

.pps-select-all-wrap label {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    color: var(--pps-primary);
    cursor: pointer;
    user-select: none;
}

.pps-select-all-wrap input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--pps-primary);
    cursor: pointer;
}

/* ============================================
   搜索结果列表
   ============================================ */
.pps-results {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.pps-loading {
    text-align: center;
    padding: 60px 20px;
    color: var(--pps-text-muted);
    font-size: 16px;
}

.pps-loading::before {
    content: '';
    display: block;
    width: 40px;
    height: 40px;
    margin: 0 auto 16px;
    border: 3px solid var(--pps-border);
    border-top-color: var(--pps-primary);
    border-radius: 50%;
    animation: pps-spin 0.8s linear infinite;
}

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

.pps-no-results {
    text-align: center;
    padding: 80px 20px;
    color: var(--pps-text-muted);
}

.pps-no-results h3 {
    margin: 0 0 8px;
    font-size: 18px;
    color: var(--pps-text);
}

.pps-no-results p {
    margin: 0;
    font-size: 14px;
}

/* ============================================
   试卷卡片
   ============================================ */
.pps-paper-card {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 16px;
    padding: 18px 20px;
    background: var(--pps-bg-card);
    border-radius: var(--pps-radius);
    box-shadow: var(--pps-shadow-sm);
    border: 2px solid transparent;
    transition: var(--pps-transition);
}

.pps-paper-card:hover {
    box-shadow: var(--pps-shadow);
    transform: translateY(-2px);
}

.pps-paper-card.selected {
    border-color: var(--pps-primary);
    background: var(--pps-primary-light);
}

/* 复选框区域 */
.pps-paper-checkbox {
    display: flex;
    align-items: center;
    justify-content: center;
}

.pps-paper-checkbox input[type="checkbox"] {
    width: 20px;
    height: 20px;
    accent-color: var(--pps-primary);
    cursor: pointer;
    margin: 0;
}

/* 试卷信息 */
.pps-paper-info {
    min-width: 0;
}

.pps-paper-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--pps-text);
    margin-bottom: 8px;
    line-height: 1.4;
    word-break: break-word;
}

.pps-paper-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

/* 标签样式 */
.pps-tag {
    display: inline-block;
    padding: 4px 10px;
    font-size: 11px;
    font-weight: 600;
    border-radius: 4px;
    text-transform: uppercase;
    letter-spacing: 0.3px;
    white-space: nowrap;
}

.pps-tag-subject {
    background: var(--pps-primary-light);
    color: var(--pps-primary);
}

.pps-tag-board {
    background: var(--pps-warning-light);
    color: #b45309;
}

.pps-tag-level {
    background: var(--pps-success-light);
    color: #047857;
}

.pps-tag-year {
    background: var(--pps-purple-light);
    color: var(--pps-purple);
}

.pps-tag-type {
    background: var(--pps-pink-light);
    color: var(--pps-pink);
}

.pps-tag-type.qp {
    background: var(--pps-primary-light);
    color: var(--pps-primary);
}

.pps-tag-type.ms {
    background: var(--pps-success-light);
    color: var(--pps-success);
}

.pps-tag-session {
    background: #e0f2fe;
    color: #0284c7;
}

.pps-tag-code {
    background: #f3e8ff;
    color: #9333ea;
    font-family: 'SF Mono', Monaco, 'Cascadia Code', monospace;
}

.pps-tag-time {
    background: #f1f5f9;
    color: #64748b;
    font-size: 10px;
}

/* 操作按钮 */
.pps-paper-actions {
    display: flex;
    gap: 8px;
    flex-shrink: 0;
}

.pps-download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 10px 16px;
    font-size: 13px;
    font-weight: 600;
    color: #fff;
    background: var(--pps-primary);
    border: none;
    border-radius: var(--pps-radius-sm);
    text-decoration: none;
    cursor: pointer;
    transition: var(--pps-transition);
    white-space: nowrap;
}

.pps-download-btn:hover {
    background: var(--pps-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--pps-shadow-sm);
    color: #fff;
    text-decoration: none;
}

.pps-download-btn svg {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
}

/* ============================================
   分页
   ============================================ */
.pps-pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 6px;
    margin-top: 28px;
    padding-top: 24px;
    border-top: 1px solid var(--pps-border);
    flex-wrap: wrap;
}

.pps-pagination button {
    min-width: 40px;
    height: 40px;
    padding: 0 14px;
    font-size: 14px;
    font-weight: 500;
    color: var(--pps-text-muted);
    background: var(--pps-bg-card);
    border: 2px solid var(--pps-border);
    border-radius: var(--pps-radius-sm);
    cursor: pointer;
    transition: var(--pps-transition);
}

.pps-pagination button:hover:not(:disabled) {
    color: var(--pps-primary);
    border-color: var(--pps-primary);
    background: var(--pps-primary-light);
}

.pps-pagination button:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.pps-pagination button.active {
    color: #fff;
    background: var(--pps-primary);
    border-color: var(--pps-primary);
}

.pps-pagination .pps-page-info {
    padding: 0 12px;
    font-size: 13px;
    color: var(--pps-text-light);
    white-space: nowrap;
}

/* ============================================
   下载进度弹窗
   ============================================ */
.pps-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: 99999;
    padding: 20px;
    backdrop-filter: blur(4px);
}

.pps-modal {
    background: var(--pps-bg-card);
    border-radius: var(--pps-radius-lg);
    padding: 32px;
    max-width: 420px;
    width: 100%;
    text-align: center;
    box-shadow: var(--pps-shadow-lg);
    animation: pps-modal-in 0.3s ease;
}

@keyframes pps-modal-in {
    from {
        opacity: 0;
        transform: scale(0.9) translateY(20px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.pps-modal h3 {
    margin: 0 0 16px;
    font-size: 20px;
    color: var(--pps-text);
}

.pps-modal p {
    margin: 0 0 24px;
    font-size: 14px;
    color: var(--pps-text-muted);
    line-height: 1.6;
}

.pps-progress-bar {
    height: 8px;
    background: var(--pps-border);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 16px;
}

.pps-progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--pps-primary) 0%, var(--pps-success) 100%);
    border-radius: 4px;
    transition: width 0.3s ease;
}

.pps-progress-text {
    font-size: 14px;
    color: var(--pps-text-muted);
    margin-bottom: 20px;
}

.pps-modal-btn {
    padding: 12px 28px;
    font-size: 14px;
    font-weight: 600;
    color: #fff;
    background: var(--pps-primary);
    border: none;
    border-radius: var(--pps-radius-sm);
    cursor: pointer;
    transition: var(--pps-transition);
}

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

.pps-modal-btn.pps-btn-secondary {
    color: var(--pps-text-muted);
    background: var(--pps-bg);
    margin-left: 12px;
}

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

/* ============================================
   响应式设计 - 平板 (768px - 1024px)
   ============================================ */
@media (max-width: 1024px) {
    .pps-container {
        padding: 20px;
    }
    
    .pps-filter-row {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .pps-tabs {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
}

/* ============================================
   响应式设计 - 大手机/小平板 (576px - 768px)
   ============================================ */
@media (max-width: 768px) {
    .pps-container {
        padding: 16px;
        border-radius: var(--pps-radius);
    }
    
    /* 选项卡 */
    .pps-tabs {
        margin-bottom: 16px;
    }
    
    .pps-tab {
        padding: 10px 14px;
        font-size: 13px;
    }
    
    /* 搜索栏垂直排列 */
    .pps-search-bar {
        flex-direction: column;
    }
    
    .pps-search-bar input {
        padding: 14px 16px;
    }
    
    .pps-search-bar button {
        width: 100%;
        padding: 14px 20px;
    }
    
    /* 筛选器2列 */
    .pps-filter-row {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }
    
    .pps-filters {
        padding: 16px;
    }
    
    /* 指南 */
    .pps-guide {
        padding: 16px;
    }
    
    .pps-guide-content {
        font-size: 13px;
    }
    
    /* 批量工具栏 */
    .pps-batch-toolbar {
        flex-direction: column;
        align-items: stretch;
        gap: 12px;
        padding: 14px 16px;
    }
    
    .pps-batch-info {
        justify-content: center;
    }
    
    .pps-batch-actions {
        justify-content: center;
    }
    
    /* 统计栏 */
    .pps-stats-bar {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }
    
    /* 试卷卡片垂直排列 */
    .pps-paper-card {
        grid-template-columns: auto 1fr;
        grid-template-rows: auto auto;
        gap: 12px;
        padding: 14px 16px;
    }
    
    .pps-paper-checkbox {
        grid-row: 1 / 3;
        align-self: start;
        padding-top: 4px;
    }
    
    .pps-paper-info {
        grid-column: 2;
    }
    
    .pps-paper-actions {
        grid-column: 2;
        justify-content: flex-start;
    }
    
    .pps-download-btn {
        flex: 1;
        max-width: 200px;
    }
    
    /* 分页 */
    .pps-pagination {
        gap: 4px;
    }
    
    .pps-pagination button {
        min-width: 36px;
        height: 36px;
        padding: 0 10px;
        font-size: 13px;
    }
    
    .pps-pagination .pps-page-info {
        width: 100%;
        text-align: center;
        padding: 8px 0 0;
        order: 10;
    }
}

/* ============================================
   响应式设计 - 手机 (< 576px)
   ============================================ */
@media (max-width: 576px) {
    .pps-container {
        padding: 12px;
        margin: 0 -12px;
        border-radius: 0;
        background: transparent;
    }
    
    /* 选项卡滚动 */
    .pps-tabs {
        gap: 0;
        padding-bottom: 0;
    }
    
    .pps-tab {
        padding: 10px 12px;
        font-size: 12px;
        flex-shrink: 0;
    }
    
    /* 筛选器单列 */
    .pps-filter-row {
        grid-template-columns: 1fr;
        gap: 10px;
    }
    
    /* 历史头部 */
    .pps-history-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }
    
    .pps-history-header h3 {
        font-size: 16px;
    }
    
    .pps-filters {
        padding: 14px;
        border-radius: var(--pps-radius-sm);
    }
    
    .pps-filter-group select {
        padding: 12px 32px 12px 14px;
        font-size: 15px;
    }
    
    .pps-filter-actions {
        margin-top: 4px;
    }
    
    .pps-filter-actions button {
        width: 100%;
    }
    
    /* 批量按钮 */
    .pps-batch-btn {
        flex: 1;
        justify-content: center;
        padding: 12px 14px;
    }
    
    /* 标签换行显示 */
    .pps-paper-meta {
        gap: 4px;
    }
    
    .pps-tag {
        font-size: 10px;
        padding: 3px 8px;
    }
    
    .pps-paper-title {
        font-size: 14px;
    }
    
    /* 下载按钮全宽 */
    .pps-download-btn {
        max-width: none;
        padding: 12px 16px;
    }
    
    /* 弹窗 */
    .pps-modal {
        padding: 24px 20px;
        margin: 12px;
    }
    
    .pps-modal h3 {
        font-size: 18px;
    }
}

/* ============================================
   响应式设计 - 超小屏幕 (< 360px)
   ============================================ */
@media (max-width: 360px) {
    .pps-container {
        padding: 8px;
    }
    
    .pps-search-bar input,
    .pps-search-bar button {
        padding: 12px 14px;
        font-size: 15px;
    }
    
    .pps-paper-card {
        padding: 12px;
    }
    
    .pps-paper-checkbox input[type="checkbox"] {
        width: 18px;
        height: 18px;
    }
    
    .pps-batch-actions {
        flex-direction: column;
    }
    
    .pps-batch-btn {
        width: 100%;
    }
}

/* ============================================
   深色模式
   ============================================ */
@media (prefers-color-scheme: dark) {
    :root {
        --pps-bg: #0f172a;
        --pps-bg-card: #1e293b;
        --pps-border: #334155;
        --pps-text: #f1f5f9;
        --pps-text-muted: #94a3b8;
        --pps-text-light: #64748b;
        --pps-primary-light: rgba(37, 99, 235, 0.2);
        --pps-success-light: rgba(16, 185, 129, 0.2);
        --pps-warning-light: rgba(245, 158, 11, 0.2);
        --pps-purple-light: rgba(139, 92, 246, 0.2);
        --pps-pink-light: rgba(236, 72, 153, 0.2);
    }
    
    .pps-filter-group select {
        background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394a3b8' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    }
    
    .pps-stats-bar {
        background: rgba(37, 99, 235, 0.15);
    }
    
    .pps-paper-card.selected {
        background: rgba(37, 99, 235, 0.15);
    }
    
    .pps-modal-overlay {
        background: rgba(0, 0, 0, 0.8);
    }
}

/* ============================================
   打印样式
   ============================================ */
@media print {
    .pps-search-bar,
    .pps-filters,
    .pps-batch-toolbar,
    .pps-pagination,
    .pps-paper-checkbox,
    .pps-paper-actions {
        display: none !important;
    }
    
    .pps-container {
        background: none;
        padding: 0;
    }
    
    .pps-paper-card {
        box-shadow: none;
        border: 1px solid #ccc;
        page-break-inside: avoid;
    }
}

/* ============================================
   动画效果
   ============================================ */
.pps-paper-card {
    animation: pps-fade-in 0.3s ease;
}

@keyframes pps-fade-in {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 延迟动画 - 为每个卡片添加递增延迟 */
.pps-paper-card:nth-child(1) { animation-delay: 0.02s; }
.pps-paper-card:nth-child(2) { animation-delay: 0.04s; }
.pps-paper-card:nth-child(3) { animation-delay: 0.06s; }
.pps-paper-card:nth-child(4) { animation-delay: 0.08s; }
.pps-paper-card:nth-child(5) { animation-delay: 0.10s; }
.pps-paper-card:nth-child(6) { animation-delay: 0.12s; }
.pps-paper-card:nth-child(7) { animation-delay: 0.14s; }
.pps-paper-card:nth-child(8) { animation-delay: 0.16s; }
.pps-paper-card:nth-child(9) { animation-delay: 0.18s; }
.pps-paper-card:nth-child(10) { animation-delay: 0.20s; }

/* ============================================
   辅助类
   ============================================ */
.pps-sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* 触摸设备优化 */
@media (hover: none) and (pointer: coarse) {
    .pps-paper-card:hover {
        transform: none;
        box-shadow: var(--pps-shadow-sm);
    }
    
    .pps-download-btn:hover {
        transform: none;
    }
    
    .pps-search-bar button:hover {
        transform: none;
    }
}