:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-pale: #eff6ff;
    --secondary: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --text-main: #1f2937;
    --text-muted: #6b7280;
    --bg-body: #f3f4f6;
    --bg-card: #ffffff;
    --border-color: #e5e7eb;
    --radius: 12px;
    --shadow: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
}

[data-theme="dark"] {
    --text-main: #f3f4f6;
    --text-muted: #9ca3af;
    --bg-body: #111827;
    --bg-card: #1f2937;
    --border-color: #374151;
    --primary-pale: #1e3a8a;
}

* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg-body);
    color: var(--text-main);
    min-height: 100vh;
}

#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.app-header {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
    white-space: nowrap;
}

.logo-icon {
    font-size: 1.5rem;
}

.main-nav {
    display: flex;
    gap: 0.25rem;
}

.nav-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    padding: 1rem 0.75rem;
    cursor: pointer;
    font-size: 0.9rem;
    border-bottom: 3px solid transparent;
    transition: all 0.2s;
}

.nav-btn:hover, .nav-btn.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-small {
    background: var(--primary-pale);
    border: 1px solid var(--border-color);
    color: var(--primary);
    padding: 0.35rem 0.6rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: transparent;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-main);
}

.mobile-menu-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 150;
}

.mobile-menu {
    display: none;
    position: fixed;
    top: 0;
    right: 0;
    width: 260px;
    height: 100%;
    background: var(--bg-card);
    z-index: 200;
    flex-direction: column;
    padding: 1rem;
    box-shadow: var(--shadow);
}

.mobile-menu-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.mobile-menu-close {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    color: var(--text-main);
    cursor: pointer;
}

.mobile-menu-nav {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.mobile-nav-btn {
    background: transparent;
    border: none;
    text-align: left;
    padding: 0.75rem;
    color: var(--text-muted);
    font-size: 1rem;
    border-radius: 8px;
    cursor: pointer;
}

.mobile-nav-btn.active, .mobile-nav-btn:hover {
    background: var(--primary-pale);
    color: var(--primary);
}

.main-content {
    flex: 1;
    padding: 1.5rem;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.page {
    display: none;
}

.page.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

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

.hero {
    background: linear-gradient(135deg, var(--primary) 0%, #3b82f6 100%);
    color: white;
    padding: 3rem 2rem;
    border-radius: var(--radius);
    text-align: center;
    margin-bottom: 1.5rem;
}

.hero h1 {
    margin: 0 0 1rem;
    font-size: 2rem;
}

.hero p {
    margin: 0 0 1.5rem;
    opacity: 0.95;
    font-size: 1.1rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn-primary {
    background: white;
    color: var(--primary);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    font-size: 1rem;
    transition: transform 0.2s;
}

.btn-primary:hover {
    transform: translateY(-2px);
}

.btn-secondary {
    background: rgba(255,255,255,0.2);
    color: white;
    border: 1px solid rgba(255,255,255,0.4);
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    font-size: 1rem;
}

.page-header {
    margin-bottom: 1.5rem;
}

.page-header h1 {
    margin: 0 0 0.5rem;
    font-size: 1.75rem;
}

.page-header p {
    margin: 0;
    color: var(--text-muted);
}

.card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.25rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    margin-bottom: 1rem;
}

.knowledge-map {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 1rem;
}

.module-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.25rem;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--primary);
}

.module-card h3 {
    margin: 0 0 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.node-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.node-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.6rem 0.75rem;
    border-radius: 8px;
    background: var(--bg-body);
    cursor: pointer;
    transition: all 0.2s;
    color: inherit;
    text-decoration: none;
}

.node-item:hover {
    background: var(--primary-pale);
}

.node-item.locked {
    opacity: 0.5;
    cursor: not-allowed;
}

.node-status {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 2px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.7rem;
}

.node-status.done {
    background: var(--secondary);
    border-color: var(--secondary);
    color: white;
}

.node-status.current {
    border-color: var(--primary);
    background: var(--primary);
    color: white;
}

.node-layers {
    display: flex;
    gap: 0.25rem;
    margin-right: 0.5rem;
}

.layer-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--border-color);
    display: inline-block;
}

.layer-dot.easy.done { background: #16a34a; }
.layer-dot.medium.done { background: #f59e0b; }
.layer-dot.hard.done { background: #dc2626; }
.layer-dot.weak { background: #dc2626; opacity: 0.5; }

.score-overview, .recommendation-section, .level-overview, .study-plan-section {
    margin-bottom: 1.5rem;
}

/* 学习计划卡片 */
.plan-card .plan-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.plan-card .plan-header h3 {
    margin: 0;
    font-size: 1.1rem;
}

.plan-badge {
    background: var(--primary-pale);
    color: var(--primary);
    padding: 0.25rem 0.6rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.plan-badge.done {
    background: var(--secondary);
    color: white;
}

.plan-settings {
    background: var(--bg-body);
    border-radius: 8px;
    padding: 0.75rem;
    margin-bottom: 0.75rem;
}

.plan-form-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

.plan-form-row label {
    color: var(--text-muted);
    font-size: 0.9rem;
    min-width: 6rem;
}

.plan-form-row input[type="date"],
.plan-form-row input[type="number"] {
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-card);
    color: var(--text-main);
}

.plan-summary {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.progress-ring {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: conic-gradient(var(--primary) calc(var(--pct, 0%)), var(--border-color) 0);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    flex-shrink: 0;
}

.progress-ring::before {
    content: '';
    position: absolute;
    inset: 6px;
    border-radius: 50%;
    background: var(--bg-card);
}

.progress-ring span {
    position: relative;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--primary);
}

.plan-meta {
    flex: 1;
    min-width: 160px;
}

.plan-count {
    font-weight: 600;
}

.plan-note {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-top: 0.25rem;
}

.plan-actions {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.task-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.task-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    padding: 0.6rem 0.75rem;
    border-radius: 8px;
    background: var(--bg-body);
    transition: background 0.2s;
}

.task-item:hover {
    background: var(--primary-pale);
}

.task-item.done {
    opacity: 0.7;
}

.task-item.done .task-check span {
    text-decoration: line-through;
    color: var(--text-muted);
}

.task-check {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    flex: 1;
}

.task-check input {
    cursor: pointer;
}

.score-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.score-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1rem;
    text-align: center;
    box-shadow: var(--shadow);
}

.score-card .value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
}

.score-card .label {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.practice-filters {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.filter-btn {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
}

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

.question-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.question-card .q-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.question-card .q-body {
    font-size: 1.1rem;
    line-height: 1.7;
    margin-bottom: 1.25rem;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
}

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

.option.correct {
    border-color: var(--secondary);
    background: #ecfdf5;
}

.option.wrong {
    border-color: var(--danger);
    background: #fef2f2;
}

.option input {
    cursor: pointer;
}

.q-actions {
    margin-top: 1.25rem;
    display: flex;
    gap: 0.75rem;
}

.explanation {
    margin-top: 1rem;
    padding: 1rem;
    background: var(--primary-pale);
    border-radius: 8px;
    border-left: 4px solid var(--primary);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.progress-bar {
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-top: 0.5rem;
}

.progress-fill {
    height: 100%;
    background: var(--primary);
    border-radius: 4px;
    transition: width 0.5s ease;
}

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

/* Toast 提示 */
.toast-container {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    pointer-events: none;
}

.toast {
    background: var(--bg-card);
    color: var(--text-main);
    border-left: 4px solid var(--primary);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    box-shadow: var(--shadow);
    min-width: 220px;
    max-width: 360px;
    opacity: 0;
    transform: translateX(20px);
    transition: opacity 0.3s, transform 0.3s;
    pointer-events: auto;
}

.toast.show {
    opacity: 1;
    transform: translateX(0);
}

.toast-success { border-left-color: var(--secondary); }
.toast-error { border-left-color: var(--danger); }
.toast-warning { border-left-color: var(--warning); }
.toast-info { border-left-color: var(--primary); }

/* 筛选栏 */
.filter-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    align-items: center;
    margin-bottom: 1rem;
    padding: 0.75rem;
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border-color);
}

.filter-bar input[type="text"] {
    padding: 0.45rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-body);
    color: var(--text-main);
    min-width: 180px;
}

.filter-bar .filter-toggle {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-body);
    color: var(--text-main);
    cursor: pointer;
    font-size: 0.9rem;
    user-select: none;
}

.filter-bar .filter-toggle input {
    margin: 0;
    cursor: pointer;
}

.filter-bar .filter-toggle.active {
    background: var(--primary-pale);
    border-color: var(--primary);
    color: var(--primary);
}

/* 倍速控制 */
.speed-control {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    margin-top: 0.5rem;
    flex-wrap: wrap;
}

.speed-control span {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-right: 0.25rem;
}

.speed-btn {
    background: var(--bg-body);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
}

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

/* 加载状态 */
.loading-state {
    text-align: center;
    padding: 2rem;
    color: var(--text-muted);
}

.spinner {
    display: inline-block;
    width: 1.5rem;
    height: 1.5rem;
    border: 2px solid var(--border-color);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-right: 0.5rem;
    vertical-align: middle;
}

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

/* 隐藏工具类 */
.hidden {
    display: none !important;
}

.home-footer {
    margin-top: 2rem;
    opacity: 0.9;
    font-size: 0.85rem;
}

.home-footer p {
    margin: 0.25rem 0;
}

.exam-config {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.exam-config label {
    font-weight: 600;
}

.exam-config select {
    padding: 0.5rem;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    color: var(--text-main);
    min-width: 220px;
}

.exam-timer {
    position: sticky;
    top: 64px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 0.75rem 1rem;
    border-radius: var(--radius);
    text-align: center;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 1rem;
    z-index: 50;
}

.question-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.exam-actions {
    margin-top: 1.5rem;
    text-align: center;
}

.result-card {
    text-align: center;
}

.result-card .score-card {
    margin: 1rem auto;
}

.correct-card {
    border-left: 4px solid var(--secondary);
}

.wrong-card {
    border-left: 4px solid var(--danger);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.data-table th, .data-table td {
    padding: 0.6rem;
    border-bottom: 1px solid var(--border-color);
    text-align: left;
}

.data-table th {
    color: var(--text-muted);
    font-weight: 600;
}

.exam-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.exam-list-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem;
    border-radius: 8px;
    background: var(--bg-body);
    cursor: pointer;
    transition: all 0.2s;
}

.exam-list-item:hover {
    background: var(--primary-pale);
}

.exam-list-item .exam-meta {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-align: right;
}

.exam-viewer {
    margin-top: 1.5rem;
}

.exam-text {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-family: inherit;
    line-height: 1.7;
    max-height: 70vh;
    overflow: auto;
    background: var(--bg-body);
    padding: 1rem;
    border-radius: 8px;
}

.ai-section {
    margin-bottom: 1.5rem;
}

.ai-section h4 {
    margin: 0 0 0.5rem;
    color: var(--primary);
}

.ai-config {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.ai-config label {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    cursor: pointer;
}

.ai-tabs {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-body);
    color: var(--text-main);
    font-family: inherit;
    font-size: 1rem;
    resize: vertical;
    margin-top: 0.5rem;
}

#api-config input, #api-config select {
    display: block;
    width: 100%;
    margin-bottom: 0.5rem;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-body);
    color: var(--text-main);
}

@media (max-width: 768px) {
    .main-nav, .user-info {
        display: none;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    .mobile-menu-overlay.show, .mobile-menu.show {
        display: block;
    }

    .mobile-menu.show {
        display: flex;
    }

    .hero h1 {
        font-size: 1.5rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .knowledge-map {
        grid-template-columns: 1fr;
    }

    .exam-config {
        flex-direction: column;
        align-items: stretch;
    }

    .exam-list-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.25rem;
    }

    .exam-list-item .exam-meta {
        text-align: left;
    }
}

/* 用户认证与排行榜 */

.user-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

#auth-ui {
    display: flex;
    align-items: center;
    gap: 0.35rem;
}

.auth-nickname {
    font-weight: 600;
    color: var(--primary);
    max-width: 100px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 1rem;
}

.modal-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 420px;
    max-height: 90vh;
    overflow-y: auto;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    margin: 0;
}

.modal-close {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-muted);
}

.modal-body {
    padding: 1.25rem;
}

.modal-form {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.modal-form label {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: -0.25rem;
}

.modal-form input,
.modal-form select {
    padding: 0.6rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-main);
    font-size: 0.95rem;
}

.modal-form input:disabled {
    background: var(--bg-body);
    color: var(--text-muted);
}

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

.leaderboard-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.leaderboard-table th,
.leaderboard-table td {
    padding: 0.6rem 0.5rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.leaderboard-table th {
    color: var(--text-muted);
    font-weight: 600;
    background: var(--bg-body);
}

.leaderboard-table tr.current-user {
    background: var(--primary-pale);
    font-weight: 600;
}

.admin-rename {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    align-items: center;
}

.admin-rename select,
.admin-rename input {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-main);
}

@media (max-width: 640px) {
    .auth-nickname {
        max-width: 60px;
    }

    .leaderboard-table {
        font-size: 0.8rem;
    }

    .leaderboard-table th,
    .leaderboard-table td {
        padding: 0.45rem 0.3rem;
    }
}

/* 1-4 级螺旋通关体系 */
.level-overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
    margin-top: 1rem;
}

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

.level-overview-card.locked {
    opacity: 0.7;
    filter: grayscale(0.6);
}

.level-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.level-card.locked {
    opacity: 0.85;
    filter: grayscale(0.5);
}

.level-header {
    margin-bottom: 1rem;
}

.level-header h2 {
    margin: 0 0 0.25rem;
}

.level-badge {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: 999px;
    background: var(--primary-pale);
    color: var(--primary);
    font-size: 0.8rem;
    font-weight: 600;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}

.category-card {
    background: var(--bg-body);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1rem;
}

.category-card h3 {
    margin: 0 0 0.75rem;
    font-size: 1rem;
}

.node-item.locked {
    opacity: 0.7;
    cursor: not-allowed;
    background: var(--bg-body);
}

.node-status.locked {
    background: var(--text-muted);
    color: #fff;
}