:root {
    --primary: #2563eb;
    --primary-light: #dbeafe;
    --primary-dark: #1e40af;
    --accent: #f59e0b;
    --accent-light: #fef3c7;
    --success: #16a34a;
    --success-light: #dcfce7;
    --danger: #dc2626;
    --danger-light: #fee2e2;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-500: #64748b;
    --gray-700: #334155;
    --gray-900: #0f172a;
    --radius: 12px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.12);
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, "Microsoft YaHei", "PingFang SC", "Noto Sans SC", sans-serif;
    background: linear-gradient(135deg, #f0f4ff 0%, #fdf2f8 100%);
    color: var(--gray-900);
    line-height: 1.8;
    min-height: 100vh;
}

/* Code blocks — dark background as fallback, highlight.js enriches with colors */
pre {
    background: #282c34;
    color: #abb2bf;
    padding: 16px;
    border-radius: 8px;
    overflow-x: auto;
    tab-size: 4;
    -moz-tab-size: 4;
    white-space: pre;
}

pre code {
    font-family: "JetBrains Mono", "Consolas", "Fira Code", "Cascadia Code", monospace;
    font-size: 0.88em;
    line-height: 1.65;
    background: none;
    padding: 0;
    color: inherit;
}

/* highlight.js adds .hljs class at runtime; our fallback matches its theme */
pre code.hljs {
    background: none;
    padding: 0;
}

/* Inline code in Markdown content */
:not(pre) > code {
    background: var(--gray-100);
    color: #d63384;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: "JetBrains Mono", "Consolas", "Fira Code", monospace;
    font-size: 0.9em;
}

/* Navbar */
.navbar {
    background: #fff;
    box-shadow: var(--shadow);
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.2em;
    font-weight: 700;
    color: var(--primary-dark);
}

.logo {
    font-size: 1.3em;
}

.nav-links {
    display: flex;
    gap: 8px;
    align-items: center;
}

.nav-links a {
    color: var(--gray-700);
    text-decoration: none;
    padding: 8px 16px;
    border-radius: 8px;
    font-weight: 500;
    transition: var(--transition);
}

.nav-links a:hover {
    background: var(--gray-100);
    color: var(--primary);
}

.nav-links a.logout {
    color: var(--danger);
}

.nav-links a.logout:hover {
    background: var(--danger-light);
}

/* Main content */
.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 32px 24px 60px;
}

/* Flash messages */
.flash-messages {
    margin-bottom: 24px;
}

.flash {
    padding: 12px 18px;
    border-radius: 8px;
    margin-bottom: 10px;
    font-weight: 500;
}

.flash-success { background: var(--success-light); color: var(--success); border-left: 4px solid var(--success); }
.flash-danger { background: var(--danger-light); color: var(--danger); border-left: 4px solid var(--danger); }
.flash-warning { background: var(--accent-light); color: #92400e; border-left: 4px solid var(--accent); }
.flash-info { background: var(--primary-light); color: var(--primary-dark); border-left: 4px solid var(--primary); }

/* Page header */
.page-header {
    margin-bottom: 28px;
}

.page-header h1 {
    font-size: 1.8em;
    color: var(--gray-900);
    margin-bottom: 6px;
}

.page-header p {
    color: var(--gray-500);
}

/* Login choice */
.login-choice {
    text-align: center;
    padding: 60px 20px;
}

.login-choice h1 {
    font-size: 2.2em;
    margin-bottom: 8px;
    color: var(--primary-dark);
}

.subtitle {
    color: var(--gray-500);
    font-size: 1.1em;
    margin-bottom: 40px;
}

.choice-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    max-width: 700px;
    margin: 0 auto;
}

.choice-card {
    background: #fff;
    border-radius: var(--radius);
    padding: 40px 30px;
    text-decoration: none;
    color: var(--gray-900);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 2px solid transparent;
}

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

.choice-icon {
    font-size: 3em;
    margin-bottom: 16px;
}

.choice-card h2 {
    font-size: 1.4em;
    margin-bottom: 10px;
    color: var(--primary-dark);
}

.choice-card p {
    color: var(--gray-500);
    font-size: 0.95em;
}

/* Login form */
.login-form-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: calc(100vh - 140px);
    padding: 20px;
}

.login-box {
    background: #fff;
    border-radius: var(--radius);
    padding: 40px;
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 420px;
}

.login-box h1 {
    text-align: center;
    margin-bottom: 8px;
    color: var(--gray-900);
}

.hint {
    text-align: center;
    color: var(--gray-500);
    font-size: 0.85em;
    margin-bottom: 28px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 600;
    color: var(--gray-700);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 12px 14px;
    border: 2px solid var(--gray-200);
    border-radius: 8px;
    font-size: 1em;
    transition: var(--transition);
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-size: 0.95em;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: var(--transition);
}

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

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

.btn-secondary {
    background: var(--gray-100);
    color: var(--gray-700);
    border: 1px solid var(--gray-200);
}

.btn-secondary:hover {
    background: var(--gray-200);
}

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

.btn-block {
    width: 100%;
    padding: 14px;
    font-size: 1.05em;
}

.btn-sm {
    padding: 6px 14px;
    font-size: 0.85em;
}

.back-link {
    margin-top: 20px;
    text-align: center;
}

.back-link a {
    color: var(--gray-500);
    text-decoration: none;
}

.back-link a:hover {
    color: var(--primary);
}

/* Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 20px;
    margin-bottom: 32px;
}

.stat-card {
    background: #fff;
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: var(--transition);
}

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

.stat-icon {
    font-size: 2em;
    margin-bottom: 10px;
}

.stat-number {
    font-size: 2.2em;
    font-weight: 800;
    color: var(--primary-dark);
    line-height: 1.2;
}

.stat-label {
    color: var(--gray-500);
    font-size: 0.9em;
    margin-top: 4px;
}

.dashboard-sections {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 24px;
}

.section-card {
    background: #fff;
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
}

.section-card h2 {
    font-size: 1.2em;
    margin-bottom: 18px;
    color: var(--gray-900);
}

.quick-actions {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

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

.data-table th,
.data-table td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
}

.data-table th {
    background: var(--gray-50);
    font-weight: 600;
    color: var(--gray-700);
}

/* Badges */
.badge {
    display: inline-block;
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 0.78em;
    font-weight: 600;
}

.badge-type { background: var(--primary-light); color: var(--primary-dark); }
.badge-chapter { background: #dbeafe; color: #1e40af; }
.badge-difficulty { background: var(--accent-light); color: #92400e; }
.badge-ai { background: #fce7f3; color: #be185d; }
.badge-score { background: var(--success-light); color: var(--success); }

/* Filter panel */
.filter-panel {
    background: #fff;
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    margin-bottom: 24px;
}

.filter-form {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.filter-row {
    display: flex;
    gap: 16px;
    align-items: flex-end;
    flex-wrap: wrap;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    min-width: 140px;
}

.filter-group label {
    font-size: 0.85em;
    font-weight: 600;
    color: var(--gray-700);
}

.filter-group select,
.filter-group input {
    padding: 10px 12px;
    border: 2px solid var(--gray-200);
    border-radius: 8px;
    font-size: 0.9em;
    min-width: 140px;
}

.filter-keyword {
    flex: 1;
    min-width: 250px;
}

.filter-keyword input {
    width: 100%;
}

.filter-actions {
    display: flex;
    gap: 10px;
}

.results-info {
    margin-bottom: 16px;
    color: var(--gray-500);
}

/* Question list */
.question-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.question-card {
    background: #fff;
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.question-card:hover {
    box-shadow: var(--shadow-lg);
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
    flex-wrap: wrap;
    gap: 10px;
}

.question-id {
    font-family: "JetBrains Mono", "Consolas", monospace;
    font-size: 0.85em;
    color: var(--gray-500);
    font-weight: 600;
}

.question-badges {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.question-content-preview {
    color: var(--gray-700);
    margin-bottom: 12px;
    line-height: 1.7;
}

.question-content-preview pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 12px;
    border-radius: 8px;
    overflow-x: auto;
    font-size: 0.85em;
}

.question-tags {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    margin-bottom: 14px;
}

.tag {
    display: inline-block;
    background: var(--gray-100);
    color: var(--gray-700);
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 0.78em;
}

.question-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    padding-top: 14px;
    border-top: 1px solid var(--gray-100);
}

.question-meta {
    display: flex;
    gap: 16px;
    color: var(--gray-500);
    font-size: 0.85em;
}

/* Question preview */
.preview-header {
    margin-bottom: 24px;
}

.preview-header h1 {
    margin-top: 12px;
}

.preview-card {
    background: #fff;
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
}

.preview-meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 12px;
}

.meta-row {
    display: flex;
    gap: 8px;
    align-items: flex-start;
}

.meta-label {
    font-weight: 600;
    color: var(--gray-700);
    white-space: nowrap;
}

.meta-value {
    color: var(--gray-900);
}

.preview-divider {
    height: 1px;
    background: var(--gray-200);
    margin: 24px 0;
}

.preview-content h3,
.preview-options h3,
.preview-answer h3,
.preview-explanation h3 {
    font-size: 1.1em;
    color: var(--primary-dark);
    margin-bottom: 12px;
}

.content-text {
    line-height: 1.8;
    color: var(--gray-800);
}

.content-text pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 16px;
    border-radius: 8px;
    overflow-x: auto;
    font-family: "JetBrains Mono", "Consolas", monospace;
    font-size: 0.9em;
    margin: 12px 0;
}

.options-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border: 2px solid var(--gray-200);
    border-radius: 8px;
    background: var(--gray-50);
}

.option-item.correct {
    border-color: var(--success);
    background: var(--success-light);
}

.option-label {
    font-weight: 700;
    color: var(--primary-dark);
    min-width: 24px;
}

.correct-mark {
    margin-left: auto;
    color: var(--success);
    font-weight: 700;
    font-size: 0.85em;
}

.answer-box {
    display: inline-block;
    background: var(--primary-light);
    color: var(--primary-dark);
    padding: 10px 24px;
    border-radius: 8px;
    font-weight: 700;
    font-size: 1.1em;
}

.explanation-box {
    background: var(--gray-50);
    border-left: 4px solid var(--accent);
    padding: 18px;
    border-radius: 0 8px 8px 0;
}

.explanation-box .callout {
    padding: 10px 14px;
    border-radius: 6px;
    margin: 12px 0;
    border-left: 4px solid;
    line-height: 1.6;
}

.explanation-box .callout.answer {
    background: #e6f4ea;
    border-color: #34a853;
    color: #1e8e3e;
}

.explanation-box .callout.note {
    background: #e8f0fe;
    border-color: #4285f4;
    color: #1967d2;
}

.explanation-box .callout.warning {
    background: #fef3e8;
    border-color: #f9ab00;
    color: #b06000;
}

.explanation-box .callout.danger {
    background: #fce8e8;
    border-color: #ea4335;
    color: #c5221f;
}

.explanation-box .callout-title {
    font-weight: 700;
    margin-bottom: 4px;
}

.ai-badge {
    display: inline-block;
    background: #fce7f3;
    color: #be185d;
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 0.78em;
    font-weight: 600;
    margin-bottom: 10px;
}

.explanation-text {
    line-height: 1.8;
    color: var(--gray-800);
}

/* Question image */
.preview-image {
    margin: 24px 0;
}

.preview-image h3,
.upload-section h3 {
    font-size: 1.1em;
    color: var(--primary-dark);
    margin-bottom: 12px;
}

.preview-image img {
    max-width: 100%;
    max-height: 600px;
    border-radius: 8px;
    border: 1px solid var(--gray-200);
    box-shadow: var(--shadow);
    display: block;
}

.remove-image-form {
    margin-top: 12px;
}

/* Image upload */
.upload-section {
    margin-top: 32px;
    padding-top: 24px;
    border-top: 2px dashed var(--gray-300);
}

.upload-dropzone {
    position: relative;
    border: 2px dashed var(--gray-300);
    border-radius: var(--radius);
    padding: 36px 24px;
    text-align: center;
    background: var(--gray-50);
    transition: var(--transition);
    cursor: pointer;
    overflow: hidden;
}

.upload-dropzone:hover,
.upload-dropzone.dragover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.upload-dropzone.uploading {
    opacity: 0.6;
    pointer-events: none;
}

.dropzone-input {
    position: absolute;
    left: 0;
    top: 0;
    opacity: 0;
    width: 0;
    height: 0;
}

.dropzone-icon {
    font-size: 2.4em;
    margin-bottom: 8px;
}

.dropzone-content p {
    margin: 6px 0;
    color: var(--gray-700);
}

.dropzone-content .link {
    color: var(--primary);
    text-decoration: underline;
    font-weight: 600;
}

.upload-hint {
    font-size: 0.85em;
    color: var(--gray-500);
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    background: #fff;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.empty-icon {
    font-size: 4em;
    margin-bottom: 16px;
}

.empty-state h2 {
    color: var(--gray-700);
    margin-bottom: 10px;
}

.empty-state p {
    color: var(--gray-500);
    margin-bottom: 20px;
}

/* Responsive */
@media (max-width: 768px) {
    .main-content {
        padding: 20px 16px;
    }
    
    .navbar {
        padding: 0 16px;
    }
    
    .dashboard-sections {
        grid-template-columns: 1fr;
    }
    
    .filter-row {
        flex-direction: column;
        align-items: stretch;
    }
    
    .filter-group,
    .filter-keyword input {
        width: 100%;
    }
    
    .question-header {
        flex-direction: column;
    }
    
    .preview-meta {
        grid-template-columns: 1fr;
    }
}

/* ================== Student Dashboard ================== */
.dashboard-container { max-width: 960px; margin: 0 auto; padding: 24px 20px 60px; }
.dashboard-header { background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%); color: #fff; padding: 40px 28px; border-radius: var(--radius); margin-bottom: 24px; box-shadow: var(--shadow-lg); }
.dashboard-header h1 { font-size: 1.8em; font-weight: 800; }
.dashboard-header .meta { opacity: 0.9; margin-top: 6px; }

.section-card { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); padding: 24px; margin-bottom: 20px; }
.section-card h2 { font-size: 1.2em; color: var(--gray-900); margin-bottom: 8px; display: flex; align-items: center; gap: 8px; }
.section-desc { color: var(--gray-500); font-size: 0.9em; margin-bottom: 16px; }

.filter-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
.filter-chip { display: flex; flex-direction: column; gap: 4px; padding: 14px 16px; background: var(--gray-50); border: 1px solid var(--gray-200); border-radius: 10px; text-decoration: none; color: var(--gray-900); transition: var(--transition); }
.filter-chip:hover { background: var(--primary-light); border-color: var(--primary); transform: translateY(-2px); }
.chip-title { font-weight: 700; font-size: 0.95em; }
.chip-sub { font-size: 0.8em; color: var(--gray-500); }

.quick-actions { display: flex; flex-wrap: wrap; gap: 12px; }
.quick-btn { display: inline-block; padding: 12px 20px; border-radius: 10px; background: var(--primary); color: #fff; font-weight: 600; text-decoration: none; transition: var(--transition); border: none; cursor: pointer; }
.quick-btn:hover { background: var(--primary-dark); transform: translateY(-1px); }
.quick-btn.secondary { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.quick-btn.secondary:hover { background: var(--primary-light); }

.recent-list { display: flex; flex-direction: column; gap: 10px; }
.recent-item { display: flex; align-items: center; gap: 12px; padding: 12px 16px; background: var(--gray-50); border-radius: 8px; border-left: 4px solid var(--gray-300); }
.recent-item.correct { border-left-color: var(--success); background: var(--success-light); }
.recent-item.wrong { border-left-color: var(--danger); background: var(--danger-light); }
.recent-status { font-size: 1.2em; font-weight: 800; }
.recent-content { flex: 1; min-width: 0; font-size: 0.9em; color: var(--gray-700); }
.recent-answer { font-size: 0.82em; color: var(--gray-500); }

/* ================== Practice Page ================== */
.practice-container { max-width: 800px; margin: 0 auto; padding: 24px 20px 60px; }
.practice-header { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); padding: 24px; margin-bottom: 20px; }
.practice-header h1 { font-size: 1.5em; color: var(--gray-900); }
.practice-meta { color: var(--gray-500); font-size: 0.9em; margin-top: 6px; }

.practice-q-card { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); padding: 24px; margin-bottom: 18px; }
.q-header { display: flex; gap: 10px; align-items: center; margin-bottom: 14px; flex-wrap: wrap; }
.q-number { font-weight: 800; color: var(--primary); font-size: 1.05em; }
.q-type { font-size: 0.75em; padding: 2px 8px; border-radius: 20px; background: var(--primary-light); color: var(--primary-dark); }
.q-score { font-size: 0.8em; color: var(--gray-500); }
/* 唯一题号（淡化展示） */
.q-uid, .uid-badge { font-size: 0.75em; color: var(--gray-400); background: var(--gray-50); padding: 1px 6px; border-radius: 4px; font-family: "JetBrains Mono", Consolas, monospace; font-weight: 500; }
.q-uid { margin-left: auto; }
.q-content { margin-bottom: 16px; }
.q-content p { margin-bottom: 10px; }
.q-content pre { background: var(--gray-100); padding: 12px; border-radius: 8px; overflow-x: auto; }
.q-content code { font-family: "Consolas", "Monaco", monospace; background: var(--gray-100); padding: 2px 6px; border-radius: 4px; }
.q-options { display: flex; flex-direction: column; gap: 10px; }
.option-label { display: flex; align-items: flex-start; gap: 12px; padding: 12px 14px; border: 1px solid var(--gray-200); border-radius: 10px; cursor: pointer; transition: var(--transition); }
.option-label:hover { background: var(--gray-50); border-color: var(--primary); }
.option-label input[type="radio"] { margin-top: 4px; }
.option-marker { display: inline-flex; align-items: center; justify-content: center; width: 26px; height: 26px; border-radius: 50%; background: var(--gray-200); color: var(--gray-700); font-weight: 700; font-size: 0.85em; flex-shrink: 0; }
.option-label:hover .option-marker { background: var(--primary); color: #fff; }
.option-text { flex: 1; color: var(--gray-800); font-size: 0.95em; }

.practice-actions { display: flex; gap: 12px; margin-top: 24px; justify-content: center; align-items: center; }

.practice-toolbar {
    display: flex; align-items: center; gap: 12px;
    padding: 10px 16px; background: #fff; border-radius: 10px;
    box-shadow: var(--shadow); margin-bottom: 16px; position: sticky; top: 0; z-index: 10;
}
.toolbar-hint { flex: 1; font-size: 0.9em; color: var(--gray-700); }
#submit-btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* Exam section headers */
.exam-section-header {
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    color: #fff; padding: 12px 24px; border-radius: 10px;
    font-weight: 700; font-size: 1em; margin: 20px 0 12px 0;
}

/* ================== Program Group (Reading/Completion) ================== */
.program-group {
    background: #fff;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 18px;
    overflow: hidden;
}

.group-program-block {
    padding: 24px;
    border-bottom: 2px solid var(--gray-200);
    background: #f0f4ff;
}

.group-program-block .program-header {
    margin-bottom: 12px;
    font-size: 0.95em;
    color: var(--gray-700);
}

.group-program-block .program-header h3 {
    font-size: 1em;
    margin: 0 0 4px 0;
}

.group-program-block .program-title {
    margin-bottom: 12px;
    font-weight: 600;
    color: var(--gray-800);
}

.group-program-block .program-description {
    margin-bottom: 16px;
    background: #fff;
    border-radius: 8px;
    font-size: 0.93em;
    color: var(--gray-700);
    line-height: 1.8;
    border: 1px solid #e2e8f0;
    overflow: hidden;
}

.program-description-label {
    background: #eff6ff;
    color: #1e40af;
    padding: 8px 16px;
    font-weight: 700;
    font-size: 0.9em;
    border-bottom: 1px solid #bfdbfe;
}

.program-description-body {
    padding: 12px 16px;
}

.group-program-block .program-code {
    margin-top: 12px;
}

.group-program-block .program-code pre {
    padding: 16px;
    border-radius: 8px;
    overflow-x: auto;
    font-family: "JetBrains Mono", "Consolas", "Fira Code", monospace;
    font-size: 0.88em;
    line-height: 1.6;
    tab-size: 4;
    -moz-tab-size: 4;
}

.group-program-block .program-code code {
    background: none;
    padding: 0;
}

/* Ensure hljs theme works inside program code blocks */
.group-program-block .program-code pre code.hljs {
    padding: 0;
    background: none;
}

.group-subquestion {
    border: none !important;
    border-radius: 0 !important;
    box-shadow: none !important;
    padding: 18px 24px !important;
    border-bottom: 1px solid var(--gray-100) !important;
    margin-bottom: 0 !important;
}

.group-subquestion:last-child {
    border-bottom: none !important;
}

.group-subquestion .q-header {
    margin-bottom: 10px;
    font-size: 0.85em;
}

/* Ensure result cards inside groups don't get left-border */
.result-card.group-subquestion {
    border-left: none !important;
    border-bottom: 1px solid var(--gray-100) !important;
    padding: 18px 24px !important;
}

.result-card.group-subquestion.correct {
    background: #f0fdf4;
}

.result-card.group-subquestion.wrong {
    background: #fef2f2;
}

.result-card.group-subquestion:last-child {
    border-bottom: none !important;
}

/* ================== Teacher Preview Group Info ================== */
.preview-group-info {
    background: #f0f4ff;
    border: 1px solid #c7d2fe;
    border-radius: 12px;
    padding: 18px;
    margin-bottom: 16px;
}

.preview-group-info h3 {
    font-size: 1em;
    margin: 0 0 10px 0;
    color: var(--primary);
}

.group-meta {
    display: flex;
    gap: 12px;
    align-items: center;
    margin-bottom: 10px;
    flex-wrap: wrap;
}

.group-id {
    font-family: "JetBrains Mono", monospace;
    background: var(--primary);
    color: #fff;
    padding: 2px 10px;
    border-radius: 6px;
    font-size: 0.9em;
}

.group-type {
    color: var(--gray-600);
    font-size: 0.9em;
}

.group-subcount {
    color: var(--gray-500);
    font-size: 0.85em;
}

.group-siblings {
    display: flex;
    gap: 6px;
    align-items: center;
    margin-bottom: 14px;
    flex-wrap: wrap;
}

.siblings-label {
    color: var(--gray-600);
    font-size: 0.85em;
    margin-right: 4px;
}

.sibling-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: 8px;
    background: var(--gray-100);
    color: var(--gray-700);
    text-decoration: none;
    font-size: 0.85em;
    font-weight: 600;
    transition: var(--transition);
}

.sibling-link:hover {
    background: var(--primary);
    color: #fff;
}

.sibling-link.current {
    background: var(--primary);
    color: #fff;
    pointer-events: none;
}

.group-program-preview {
    margin-top: 10px;
}

.group-program-preview h4 {
    font-size: 0.9em;
    color: var(--gray-600);
    margin: 0 0 8px 0;
}

.program-code-preview pre {
    padding: 14px;
    border-radius: 8px;
    overflow-x: auto;
    font-size: 0.85em;
    line-height: 1.5;
    tab-size: 4;
    -moz-tab-size: 4;
}

.program-code-preview code {
    background: none;
    padding: 0;
    color: inherit;
}

/* ================== Result Page ================== */
.result-container { max-width: 800px; margin: 0 auto; padding: 24px 20px 60px; }
.result-header { background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%); color: #fff; border-radius: var(--radius); padding: 32px; text-align: center; margin-bottom: 20px; }
.result-header h1 { font-size: 1.6em; margin-bottom: 16px; }
.result-summary { display: flex; justify-content: center; align-items: center; gap: 32px; flex-wrap: wrap; }
.result-score { display: flex; align-items: baseline; gap: 6px; }
.score-number { font-size: 3em; font-weight: 800; }
.score-total { font-size: 1.2em; opacity: 0.9; }
.result-detail { text-align: left; }
.result-detail p { margin: 4px 0; }
.result-actions { display: flex; justify-content: center; gap: 12px; margin-bottom: 24px; }
.result-actions.bottom { margin-top: 32px; }
.result-list { display: flex; flex-direction: column; gap: 16px; }
.result-card { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); padding: 22px; border-left: 5px solid var(--gray-300); }
.result-card.correct { border-left-color: var(--success); }
.result-card.wrong { border-left-color: var(--danger); }
.result-status { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; font-weight: 700; margin-bottom: 10px; font-size: 0.95em; }
.result-card.correct .result-status { color: var(--success); }
.result-card.wrong .result-status { color: var(--danger); }
.answer-row { display: flex; gap: 20px; margin: 14px 0; font-size: 0.9em; }
.your-answer strong { color: var(--danger); }
.correct-answer strong { color: var(--success); }
.explanation-box { background: var(--gray-50); border-radius: 10px; padding: 16px; margin-top: 14px; }
.explanation-title { font-weight: 700; color: var(--gray-700); margin-bottom: 8px; }

/* ================== History Page ================== */
.history-container { max-width: 1100px; margin: 0 auto; padding: 24px 20px 60px; }
.history-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 20px; }
.history-header h1 { font-size: 1.6em; color: var(--gray-900); }
.history-table-wrapper { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); overflow-x: auto; }
.data-table { width: 100%; border-collapse: collapse; }
.data-table th { background: var(--gray-100); padding: 12px 16px; text-align: left; font-weight: 700; color: var(--gray-700); font-size: 0.85em; border-bottom: 1px solid var(--gray-200); }
.data-table td { padding: 12px 16px; border-bottom: 1px solid var(--gray-200); font-size: 0.88em; vertical-align: top; }
.data-table tr:last-child td { border-bottom: none; }
.data-table .row-correct { background: var(--success-light); }
.data-table .row-wrong { background: var(--danger-light); }
.history-content { max-width: 260px; color: var(--gray-700); }
.empty-state { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); padding: 48px; text-align: center; color: var(--gray-500); }
.empty-state p { margin-bottom: 16px; }

/* ================== Filter Bar ================== */
.filter-bar {
    display: flex; gap: 8px; flex-wrap: wrap; align-items: center;
    margin-bottom: 16px; padding: 12px 16px;
    background: #fff; border-radius: 10px; box-shadow: var(--shadow);
}
.filter-chip {
    display: inline-block; padding: 6px 14px; border-radius: 20px;
    font-size: 0.85em; font-weight: 600; text-decoration: none;
    background: var(--gray-100); color: var(--gray-700);
    transition: var(--transition);
}
.filter-chip:hover { background: var(--gray-200); }
.filter-chip.active { background: var(--primary); color: #fff; }
.filter-chip.filter-correct.active { background: var(--success); }
.filter-chip.filter-wrong.active { background: var(--danger); }
.filter-select {
    padding: 6px 12px; border-radius: 8px; border: 1px solid var(--gray-200);
    font-size: 0.85em; background: #fff; color: var(--gray-700); cursor: pointer;
}
.filter-select:focus { outline: none; border-color: var(--primary); }

/* ================== History Enhancements ================== */
.history-header-actions { display: flex; gap: 8px; }
.td-time { white-space: nowrap; }
.badge-exam {
    display: block; margin-top: 2px;
    background: var(--accent-light); color: #92400e;
}

/* ================== Wrong Book ================== */
.wrong-chapter {
    background: #fff; border-radius: var(--radius); box-shadow: var(--shadow);
    margin-bottom: 14px; overflow: hidden;
}
.wrong-chapter-header {
    display: flex; align-items: center; gap: 12px;
    padding: 14px 20px; cursor: pointer; user-select: none;
    background: var(--gray-50); border-bottom: 1px solid var(--gray-200);
}
.wrong-chapter-header:hover { background: var(--gray-100); }
.chapter-title { font-weight: 700; color: var(--gray-900); flex: 1; }
.chapter-count { color: var(--danger); font-weight: 600; font-size: 0.9em; }
.collapse-icon { font-size: 0.8em; color: var(--gray-500); transition: transform 0.3s; }
.wrong-chapter.collapsed .wrong-chapter-body { display: none; }
.wrong-chapter.collapsed .collapse-icon { transform: rotate(-90deg); }
.wrong-chapter-body { padding: 0; }
.wrong-item {
    display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
    padding: 10px 20px; border-bottom: 1px solid var(--gray-100);
}
.wrong-item:last-child { border-bottom: none; }
.wrong-item-type {
    font-size: 0.75em; font-weight: 700; padding: 2px 8px;
    border-radius: 4px; background: var(--gray-200); color: var(--gray-700);
}
.wrong-item-id { font-family: monospace; font-size: 0.8em; color: var(--gray-500); }
.wrong-item-content { flex: 1; min-width: 200px; font-size: 0.85em; color: var(--gray-700); }
.wrong-item-count { color: var(--danger); font-weight: 700; font-size: 0.85em; }
.wrong-item-time { color: var(--gray-500); font-size: 0.8em; }
.wrong-item-actions { display: flex; gap: 6px; }

/* ================== Review Page ================== */
.result-meta { font-weight: 400; font-size: 0.85em; color: var(--gray-500); margin-left: 12px; }
.option-label.option-correct { border-color: var(--success); background: var(--success-light); }
.option-label.option-wrong { border-color: var(--danger); background: var(--danger-light); }
.correct-mark { color: var(--success); font-weight: 700; margin-left: auto; }
.wrong-mark { color: var(--danger); font-weight: 700; margin-left: auto; font-size: 0.85em; }

/* ================== Charts Grid & Full-Width ================== */
.charts-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin-bottom: 20px;
}
@media (max-width: 1000px) { .charts-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .charts-grid { grid-template-columns: 1fr; } }

.chart-fullwidth {
    display: flex; flex-direction: column; gap: 20px;
    margin-bottom: 20px;
}

.chart-box {
    background: #fff; border-radius: var(--radius); box-shadow: var(--shadow);
    padding: 20px;
}
.chart-box h4 { font-size: 0.95em; color: var(--gray-700); margin-bottom: 12px; }

.chart-box-full { }
.chart-box-full canvas { max-height: 350px; }
.chart-desc { font-size: 0.82em; color: var(--gray-500); margin-bottom: 14px; }

/* ================== Class Management ================== */
.class-grid { display: flex; flex-direction: column; gap: 12px; }
.class-card {
    background: #fff; border-radius: var(--radius); box-shadow: var(--shadow);
    padding: 16px 20px;
}
.class-card-header {
    display: flex; justify-content: space-between; align-items: center;
    margin-bottom: 10px;
}
.class-name { font-weight: 700; font-size: 1.1em; color: var(--gray-900); }
.class-count { color: var(--gray-500); font-size: 0.9em; }
.class-card-actions { display: flex; gap: 8px; align-items: center; }

.class-manage-card { margin-bottom: 16px; }
.class-manage-name { font-weight: 700; font-size: 1.1em; color: var(--gray-900); margin-right: 10px; }
.class-manage-count { color: var(--gray-500); font-size: 0.9em; }

.student-check-grid {
    display: flex; flex-wrap: wrap; gap: 6px;
    max-height: 200px; overflow-y: auto;
    padding: 8px; background: var(--gray-50); border-radius: 8px;
}
.student-check-item {
    display: flex; align-items: center; gap: 4px;
    padding: 4px 10px; background: #fff; border-radius: 6px;
    font-size: 0.85em; cursor: pointer;
    border: 1px solid var(--gray-200);
}
.student-check-item:hover { border-color: var(--primary); }
.student-check-item input[type="checkbox"] { margin: 0; }
.already-in-class { color: var(--gray-500); font-size: 0.8em; }
.unassigned-student {
    padding: 4px 10px; background: var(--danger-light); border-radius: 6px;
    font-size: 0.85em; color: var(--danger);
}
.empty-hint { color: var(--gray-500); font-size: 0.85em; padding: 8px 0; }

/* Exam cards */
.exam-list { display: flex; flex-direction: column; gap: 12px; }
.exam-card-item { padding: 20px; }
.exam-card-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.exam-card-header h3 { font-size: 1.1em; margin: 0; }
.exam-card-meta { color: var(--gray-500); font-size: 0.85em; margin-bottom: 12px; display: flex; gap: 8px; }
.exam-card-actions { display: flex; gap: 8px; }

/* Question edit info grid */
.edit-info-grid {
    display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 8px; padding: 14px; background: var(--gray-50); border-radius: 8px;
    margin-bottom: 16px;
}
.info-item { display: flex; gap: 8px; font-size: 0.85em; }
.info-label { color: var(--gray-500); min-width: 60px; }
.info-value { color: var(--gray-900); font-weight: 500; }

.textarea-code {
    font-family: "JetBrains Mono","Consolas",monospace; font-size: 0.85em;
    line-height: 1.6; width: 100%; padding: 12px;
    border: 1px solid var(--gray-200); border-radius: 8px;
    resize: vertical;
}
.textarea-code:focus { outline: none; border-color: var(--primary); }

/* ================== Chapter Progress Bars ================== */
.chapter-list { display: flex; flex-direction: column; gap: 12px; }
.chapter-row { }
.chapter-row-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 4px; }
.chapter-row-name { font-size: 0.85em; color: var(--gray-700); font-weight: 600; }
.chapter-row-bar { height: 8px; background: var(--gray-200); border-radius: 4px; overflow: hidden; }
.chapter-row-fill { height: 100%; border-radius: 4px; transition: width 0.5s ease; }
.chapter-row-fill.fill-green { background: var(--success); }
.chapter-row-fill.fill-red { background: var(--danger); }
.chapter-row-meta { font-size: 0.75em; color: var(--gray-500); margin-top: 2px; }

/* ================== Dashboard Stat Card Link ================== */
.stat-card-link {
    text-decoration: none; color: inherit; display: block;
    transition: var(--transition);
}
.stat-card-link:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }
.stat-card-link .stat-icon { font-size: 1.5em; margin-bottom: 4px; }

/* ================== Buttons ================== */
.btn { display: inline-block; padding: 10px 18px; border-radius: 8px; font-weight: 600; text-decoration: none; border: none; cursor: pointer; transition: var(--transition); font-size: 0.95em; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-secondary { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.btn-secondary:hover { background: var(--primary-light); }
.btn-lg { padding: 14px 28px; font-size: 1.05em; }

/* ================== Utility ================== */
.badge { display: inline-block; padding: 2px 8px; border-radius: 12px; font-size: 0.75em; font-weight: 700; }
.badge-success { background: var(--success-light); color: var(--success); }
.badge-danger { background: var(--danger-light); color: var(--danger); }
@media (max-width: 640px) {
    .result-summary { flex-direction: column; gap: 12px; }
    .answer-row { flex-direction: column; gap: 6px; }
    .filter-grid { grid-template-columns: 1fr; }
    .quick-actions { flex-direction: column; }
    .history-header { flex-direction: column; gap: 12px; align-items: flex-start; }
}

/* ================== Learning Path ================== */
.learning-path { background: linear-gradient(180deg, #fff 0%, #f8fafc 100%); }
.path-header { margin-bottom: 18px; }
.progress-bar { position: relative; height: 28px; background: var(--gray-200); border-radius: 14px; overflow: hidden; margin-bottom: 24px; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--success), #22c55e); border-radius: 14px; transition: width 0.5s ease; }
.progress-text { position: absolute; top: 0; left: 0; right: 0; bottom: 0; display: flex; align-items: center; justify-content: center; font-size: 0.82em; font-weight: 700; color: var(--gray-700); }
.chapter-path { display: flex; flex-direction: column; gap: 14px; }
.path-step { display: flex; align-items: stretch; gap: 14px; padding: 16px; background: #fff; border-radius: var(--radius); border: 1px solid var(--gray-200); transition: var(--transition); }
.path-step.completed { border-color: var(--success); background: var(--success-light); }
.path-step.started { border-color: var(--accent); background: var(--accent-light); }
.step-number { width: 36px; height: 36px; border-radius: 50%; background: var(--gray-200); color: var(--gray-700); display: flex; align-items: center; justify-content: center; font-weight: 800; flex-shrink: 0; margin-top: 2px; }
.path-step.completed .step-number { background: var(--success); color: #fff; }
.path-step.started .step-number { background: var(--accent); color: #fff; }
.step-body { flex: 1; min-width: 0; }
.step-title { font-weight: 700; font-size: 1.05em; color: var(--gray-900); margin-bottom: 4px; }
.step-meta { display: flex; gap: 12px; font-size: 0.8em; color: var(--gray-500); margin-bottom: 10px; }
.step-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.step-link { display: inline-flex; align-items: center; gap: 4px; padding: 6px 12px; border-radius: 6px; font-size: 0.85em; font-weight: 600; text-decoration: none; transition: var(--transition); }
.step-link.lecture { background: var(--primary-light); color: var(--primary-dark); }
.step-link.lecture:hover { background: var(--primary); color: #fff; }
.step-link.practice { background: var(--accent-light); color: #92400e; }
.step-link.practice:hover { background: var(--accent); color: #fff; }
.step-link.strengthen { background: #dcfce7; color: #166534; }
.step-link.strengthen:hover { background: #bbf7d0; color: #166534; }
.step-status { display: flex; align-items: center; }
.status-badge { display: inline-block; padding: 4px 10px; border-radius: 12px; font-size: 0.75em; font-weight: 700; }
.status-badge.completed { background: var(--success-light); color: var(--success); }
.status-badge.started { background: var(--accent-light); color: #92400e; }
.status-badge.pending { background: var(--gray-100); color: var(--gray-500); }

/* Mock Exam Card */
.mock-exam-card { border-left: 5px solid var(--success); }
.mock-exam-card.locked { border-left-color: var(--gray-300); opacity: 0.85; }
.mock-exam-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px; }
.mock-exam-header h2 { margin: 0; }
.mock-exam-card .quick-btn { margin-top: 12px; }
.mock-exam-card .quick-btn:disabled { background: var(--gray-300); color: var(--gray-500); cursor: not-allowed; }

/* ================== Question Edit ================== */
.question-edit { max-width: 720px; margin: 0 auto; padding: 24px 20px 60px; }
.edit-header { margin-bottom: 24px; }
.edit-header h1 { font-size: 1.6em; color: var(--gray-900); margin-top: 10px; }
.edit-card { background: #fff; border-radius: var(--radius); box-shadow: var(--shadow); padding: 28px; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-hint { font-size: 0.8em; color: var(--gray-500); margin-top: 4px; }
.required { color: var(--danger); }
.form-actions { display: flex; gap: 12px; margin-top: 24px; }
.preview-header { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.preview-header .edit-link { margin-left: auto; font-size: 0.9em; }
.questions-table .edit-link { color: var(--primary); font-size: 0.85em; }
.edit-link:hover { text-decoration: underline; }