:root {
    --primary-color: #4a90e2;
    --primary-hover: #357abd;
    --bg-color: #f5f7fa;
    --text-color: #333;
    --card-bg: #fff;
    --border-color: #e1e4e8;
    --success-color: #2ecc71;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 40px 20px;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    position: relative;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    color: #2c3e50;
}

header p {
    color: #666;
    font-size: 1.1rem;
}

.nav-link {
    display: inline-block;
    margin-top: 10px;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.nav-link:hover {
    text-decoration: underline;
}

.admin-link {
    position: absolute;
    top: 0;
    right: 0;
    background: #fff;
    padding: 8px 16px;
    border-radius: 20px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

/* 按钮通用样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    border: none;
    transition: all 0.2s;
}

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

.btn-success { background: var(--success-color); color: white; }
.btn-success:hover { background: #27ae60; }

.btn-danger { background: var(--danger-color); color: white; }
.btn-danger:hover { background: #c0392b; }

.btn-warning { background: var(--warning-color); color: white; }
.btn-warning:hover { background: #d68910; }

.btn-sm {
    padding: 6px 12px;
    font-size: 12px;
}

/* 前台卡片样式 */
.gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 25px;
}

.sample-card {
    background: var(--card-bg);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s;
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
}

.sample-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 20px rgba(0,0,0,0.1);
}

.card-icon {
    height: 140px;
    background: #eef5fc;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    border-bottom: 1px solid var(--border-color);
}

.sample-info {
    padding: 15px;
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.sample-name {
    margin: 0 0 10px 0;
    font-size: 16px;
    color: #333;
    font-weight: 600;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* PDF 预览区样式 */
.pdf-viewer-container {
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: 0 8px 30px rgba(0,0,0,0.12);
    overflow: hidden;
    height: 85vh;
    display: flex;
    flex-direction: column;
    border: 1px solid var(--border-color);
}

/* 移动端全屏预览 */
@media (max-width: 600px) {
    .pdf-viewer-container {
        position: fixed;
        top: 0; left: 0; right: 0; bottom: 0;
        height: 100vh;
        border-radius: 0;
        z-index: 1000;
    }
    body { padding: 20px 12px; }
}

/* PDF 加载 spinner */
.pdf-spinner {
    width: 40px;
    height: 40px;
    border: 4px solid rgba(255,255,255,0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 12px;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}

.viewer-header {
    padding: 15px 20px;
    background: #f8f9fa;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.viewer-header h3 {
    margin: 0;
    font-size: 1.1rem;
    color: #2c3e50;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 60%;
}

.viewer-actions {
    display: flex;
    gap: 10px;
    align-items: center;
}

.close-btn {
    background: #95a5a6;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.2s;
}

.close-btn:hover {
    background: #7f8c8d;
}

/* 后台管理样式 */
.admin-panel {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.admin-upload {
    background: var(--card-bg);
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    border: 1px solid var(--border-color);
}

.admin-upload h3 {
    margin-top: 0;
    margin-bottom: 20px;
    color: #2c3e50;
}

.form-group {
    margin-bottom: 15px;
}

.form-control {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #ccc;
    border-radius: 6px;
    font-size: 14px;
    box-sizing: border-box;
}

.list-section {
    background: var(--card-bg);
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    border: 1px solid var(--border-color);
    overflow-x: auto;
}

.list-section h3 {
    margin-top: 0;
    margin-bottom: 20px;
    color: #2c3e50;
}

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

.admin-table th, .admin-table td {
    padding: 12px 15px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.admin-table th {
    background-color: #f8f9fa;
    font-weight: 600;
    color: #555;
}

.badge {
    padding: 4px 8px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: bold;
}

.badge-success {
    background: #e8f8f5;
    color: var(--success-color);
}

.badge-secondary {
    background: #f2f3f4;
    color: #7f8c8d;
}