:root {
    --nb-primary: #2457e6;
    --nb-primary-dark: #193fae;
    --nb-secondary: #6c7a91;
    --nb-success: #1f9d68;
    --nb-warning: #f3a712;
    --nb-danger: #dc4c64;
    --nb-info: #2684ff;
    --nb-bg: #f5f7fb;
    --nb-surface: #ffffff;
    --nb-surface-soft: #f9fafc;
    --nb-text: #172033;
    --nb-muted: #718096;
    --nb-border: #e5e9f2;
    --nb-radius-sm: 8px;
    --nb-radius-md: 8px;
    --nb-radius-lg: 8px;
    --nb-shadow-sm: 0 6px 20px rgba(23, 32, 51, 0.06);
    --nb-shadow: 0 12px 35px rgba(23, 32, 51, 0.08);
}

html {
    min-height: 100%;
}

body {
    min-height: 100%;
    margin: 0;
    background: var(--nb-bg);
    color: var(--nb-text);
    font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

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

.btn-primary:hover {
    background: var(--nb-primary-dark);
    border-color: var(--nb-primary-dark);
}

a {
    color: var(--nb-primary);
}

a:focus,
button:focus {
    outline: 3px solid rgba(36, 87, 230, 0.35);
    outline-offset: 2px;
}

.nb-shell {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.nb-topbar {
    background: var(--nb-surface);
    border-bottom: 1px solid var(--nb-border);
}

.nb-brand {
    font-weight: 800;
    color: var(--nb-text);
    text-decoration: none;
}

.nb-main {
    flex: 1;
    padding: 48px 0;
}

.nb-app-shell {
    min-height: 100vh;
    display: grid;
    grid-template-columns: 292px minmax(0, 1fr);
    background: #eef1f6;
}

.nb-admin-shell {
    min-height: 100vh;
    display: grid;
    grid-template-columns: 270px minmax(0, 1fr);
    background: var(--nb-bg);
}

.nb-admin-sidebar {
    background: #101827;
    border-right: 0;
}

.nb-admin-sidebar .nb-brand,
.nb-admin-sidebar .nb-side-nav a,
.nb-admin-sidebar .nb-side-nav button,
.nb-admin-sidebar .nb-user-tile strong {
    color: #f8fafc;
}

.nb-admin-sidebar .nb-side-nav p,
.nb-admin-sidebar .nb-user-tile span {
    color: #9aa8bd;
}

.nb-admin-sidebar .nb-user-tile,
.nb-admin-sidebar .nb-side-nav a.active {
    border-color: rgba(255, 255, 255, 0.12);
    background: rgba(255, 255, 255, 0.06);
}

.nb-admin-main {
    min-width: 0;
    padding: 34px;
}

.nb-sidebar {
    background: var(--nb-surface);
    border-right: 1px solid var(--nb-border);
    padding: 28px 22px;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow: auto;
}

.nb-sidebar-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    padding-bottom: 26px;
    border-bottom: 1px solid var(--nb-border);
}

.nb-sidebar-brand span {
    display: inline-grid;
    place-items: center;
    width: 34px;
    height: 34px;
    border-radius: 8px;
    background: var(--nb-primary);
    color: #fff;
    font-size: 0.8rem;
}

.nb-user-tile {
    margin: 26px 0;
    padding: 14px;
    border: 1px solid var(--nb-border);
    border-radius: 8px;
    background: var(--nb-surface-soft);
}

.nb-user-tile strong,
.nb-user-tile span {
    display: block;
}

.nb-user-tile span {
    margin-top: 3px;
    color: var(--nb-muted);
    font-size: 0.86rem;
    overflow-wrap: anywhere;
}

.nb-side-nav {
    display: grid;
    gap: 7px;
}

.nb-side-nav p {
    margin: 22px 0 6px;
    color: var(--nb-muted);
    font-size: 0.74rem;
    font-weight: 800;
    text-transform: uppercase;
}

.nb-side-nav a,
.nb-side-nav button {
    width: 100%;
    display: flex;
    align-items: center;
    min-height: 42px;
    padding: 9px 13px;
    border: 1px solid transparent;
    border-radius: 8px;
    background: transparent;
    color: var(--nb-text);
    text-align: left;
    text-decoration: none;
}

.nb-side-nav a.active {
    border-color: var(--nb-border);
    background: #fff;
    box-shadow: var(--nb-shadow-sm);
    color: var(--nb-primary-dark);
    font-weight: 750;
}

.nb-side-nav button {
    color: var(--nb-danger);
}

.nb-workspace {
    min-width: 0;
    background: var(--nb-bg);
}

.nb-workspace-topbar {
    min-height: 82px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    padding: 18px 34px;
    background: var(--nb-surface);
    border-bottom: 1px solid var(--nb-border);
}

.nb-workspace .nb-main {
    padding: 30px 0 54px;
}

.nb-search-shell input {
    width: min(320px, 38vw);
    min-height: 38px;
    padding: 8px 14px;
    border: 1px solid var(--nb-border);
    border-radius: 8px;
    background: var(--nb-surface-soft);
}

.nb-card {
    background: var(--nb-surface);
    border: 1px solid var(--nb-border);
    border-radius: var(--nb-radius-md);
    box-shadow: var(--nb-shadow-sm);
}

.nb-page-title {
    font-size: 3.25rem;
    line-height: 1.02;
    letter-spacing: 0;
    font-weight: 850;
}

.nb-page-kicker {
    color: var(--nb-muted);
    font-size: 0.78rem;
    font-weight: 800;
    text-transform: uppercase;
}

.nb-muted {
    color: var(--nb-muted);
}

.nb-status-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.nb-status-list li {
    border-top: 1px solid var(--nb-border);
    padding: 14px 0;
}

.nb-status-list li:first-child {
    border-top: 0;
}

.nb-badge {
    display: inline-flex;
    align-items: center;
    min-height: 28px;
    padding: 4px 10px;
    border-radius: var(--nb-radius-sm);
    background: rgba(31, 157, 104, 0.12);
    color: #146c47;
    font-weight: 700;
    font-size: 0.82rem;
}

.nb-error-pre {
    overflow: auto;
    max-height: 480px;
    padding: 16px;
    border-radius: var(--nb-radius-sm);
    background: #111827;
    color: #f9fafb;
}

.nb-dashboard-grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 360px;
    gap: 28px;
    align-items: start;
}

.nb-dashboard-main,
.nb-dashboard-rail {
    min-width: 0;
}

.nb-metric {
    min-height: 112px;
    padding: 20px;
    border: 1px solid var(--nb-border);
    border-radius: 8px;
    background: var(--nb-surface);
    box-shadow: var(--nb-shadow-sm);
}

.nb-metric span,
.nb-metric strong {
    display: block;
}

.nb-metric span {
    color: var(--nb-muted);
    margin-bottom: 12px;
}

.nb-metric strong {
    font-size: clamp(1.35rem, 3vw, 2rem);
    line-height: 1.1;
}

.nb-continue-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    background: linear-gradient(135deg, #2457e6, #6f8cff);
    color: #fff;
}

.nb-continue-card .nb-muted {
    color: rgba(255, 255, 255, 0.82);
}

.nb-progress {
    width: 100%;
    height: 8px;
    overflow: hidden;
    border-radius: 999px;
    background: #e8edf6;
}

.nb-progress span {
    display: block;
    min-width: 0;
    height: 100%;
    border-radius: inherit;
    background: var(--nb-primary);
}

.nb-continue-card .nb-progress {
    background: rgba(255, 255, 255, 0.28);
}

.nb-continue-card .nb-progress span {
    background: #fff;
}

.nb-course-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
}

.nb-course-grid-wide {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.nb-course-card {
    min-height: 230px;
    display: flex;
    flex-direction: column;
    gap: 14px;
    padding: 20px;
    border: 1px solid var(--nb-border);
    border-radius: 8px;
    background: var(--nb-surface);
    box-shadow: var(--nb-shadow-sm);
}

.nb-course-card h2,
.nb-course-card h3 {
    margin: 0 0 7px;
    font-size: 1rem;
    line-height: 1.35;
}

.nb-course-card p {
    margin: 0;
    color: var(--nb-muted);
    font-size: 0.92rem;
}

.nb-course-card a {
    margin-top: auto;
    color: var(--nb-text);
    font-weight: 700;
    text-decoration: none;
}

.nb-course-icon {
    width: 44px;
    height: 44px;
    display: grid;
    place-items: center;
    border-radius: 8px;
    background: #eaf0ff;
    color: var(--nb-primary-dark);
    font-weight: 850;
}

.nb-course-meta,
.nb-progress-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    color: var(--nb-muted);
    font-size: 0.9rem;
}

.nb-progress-row .nb-progress {
    flex: 1;
}

.nb-activity-list {
    display: grid;
    gap: 12px;
}

.nb-activity-list div {
    padding: 14px;
    border: 1px solid #cfeee6;
    border-radius: 8px;
    background: #f1fcf9;
}

.nb-activity-list strong,
.nb-activity-list span {
    display: block;
}

.nb-activity-list span,
.nb-account-list dd {
    color: var(--nb-muted);
}

.nb-account-list dd {
    margin-bottom: 12px;
    overflow-wrap: anywhere;
}

.nb-mini-progress {
    min-width: 260px;
    display: grid;
    gap: 8px;
}

.nb-mini-progress span {
    font-weight: 850;
    text-align: right;
}

.nb-module-hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.nb-hero-progress {
    width: 220px;
    display: grid;
    gap: 7px;
    text-align: right;
}

.nb-hero-progress strong {
    font-size: 2.25rem;
    line-height: 1;
}

.nb-hero-progress span {
    color: var(--nb-muted);
}

.nb-list-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 18px 22px;
    border-bottom: 1px solid var(--nb-border);
}

.nb-list-header span,
.nb-lesson-meta {
    color: var(--nb-muted);
}

.nb-lesson-list {
    display: grid;
}

.nb-lesson-row {
    display: grid;
    grid-template-columns: 14px minmax(0, 1fr) auto;
    gap: 14px;
    align-items: center;
    padding: 18px 22px;
    border-bottom: 1px solid var(--nb-border);
    color: var(--nb-text);
    text-decoration: none;
}

.nb-lesson-row:last-child {
    border-bottom: 0;
}

.nb-lesson-row strong,
.nb-lesson-row small {
    display: block;
}

.nb-lesson-row small {
    margin-top: 4px;
    color: var(--nb-muted);
}

.nb-lesson-state {
    width: 11px;
    height: 11px;
    border-radius: 50%;
    background: #c9d2e3;
}

.nb-state-in_progress {
    background: var(--nb-warning);
}

.nb-state-completed {
    background: var(--nb-success);
}

.nb-lesson-layout {
    display: grid;
    grid-template-columns: 300px minmax(0, 1fr);
    gap: 24px;
}

.nb-lesson-sidebar {
    position: sticky;
    top: 104px;
    align-self: start;
    max-height: calc(100vh - 124px);
    overflow: auto;
    padding: 20px;
    border: 1px solid var(--nb-border);
    border-radius: 8px;
    background: var(--nb-surface);
    box-shadow: var(--nb-shadow-sm);
}

.nb-lesson-sidebar h2 {
    margin: 14px 0;
    font-size: 1rem;
}

.nb-lesson-sidebar nav {
    display: grid;
    gap: 8px;
}

.nb-lesson-sidebar nav a {
    display: grid;
    grid-template-columns: 12px minmax(0, 1fr);
    gap: 10px;
    align-items: center;
    padding: 10px;
    border-radius: 8px;
    color: var(--nb-text);
    text-decoration: none;
}

.nb-lesson-sidebar nav a.active {
    background: #eaf0ff;
    color: var(--nb-primary-dark);
    font-weight: 800;
}

.nb-back-link {
    color: var(--nb-muted);
    font-weight: 700;
    text-decoration: none;
}

.nb-lesson-content {
    min-height: 560px;
}

.nb-empty-lesson {
    padding: 24px;
    border: 1px dashed var(--nb-border);
    border-radius: 8px;
    background: var(--nb-surface-soft);
}

.nb-section {
    margin: 24px 0;
}

.nb-section pre {
    overflow: auto;
    padding: 16px;
    border-radius: 8px;
    background: #111827;
    color: #f9fafb;
}

.nb-lesson-actions {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    margin-top: 32px;
    padding-top: 20px;
    border-top: 1px solid var(--nb-border);
}

.nb-admin-table {
    vertical-align: middle;
}

.nb-admin-table th {
    padding: 16px 18px;
    color: var(--nb-muted);
    font-size: 0.78rem;
    text-transform: uppercase;
}

.nb-admin-table td {
    padding: 16px 18px;
}

.nb-admin-table td span {
    display: block;
    color: var(--nb-muted);
    font-size: 0.86rem;
}

.nb-admin-status {
    display: inline-flex;
    align-items: center;
    min-height: 28px;
    padding: 4px 10px;
    border-radius: 8px;
    font-size: 0.78rem;
    font-weight: 800;
}

.nb-status-draft {
    background: #eef2f7;
    color: #526174;
}

.nb-status-published {
    background: #e8f7f1;
    color: #157050;
}

.nb-status-archived {
    background: #fff0f1;
    color: #af3448;
}

@media (max-width: 1180px) {
    .nb-dashboard-grid,
    .nb-course-grid-wide {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .nb-dashboard-rail {
        grid-column: 1 / -1;
    }
}

@media (max-width: 920px) {
    .nb-app-shell,
    .nb-admin-shell {
        display: block;
    }

    .nb-sidebar {
        position: static;
        height: auto;
        padding: 18px;
    }

    .nb-side-nav {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .nb-side-nav p {
        grid-column: 1 / -1;
    }

    .nb-workspace-topbar {
        padding: 16px 18px;
    }

    .nb-admin-main {
        padding: 22px 18px;
    }

    .nb-dashboard-grid,
    .nb-course-grid,
    .nb-course-grid-wide,
    .nb-lesson-layout {
        grid-template-columns: 1fr;
    }

    .nb-lesson-sidebar {
        position: static;
        max-height: none;
    }
}

@media (max-width: 640px) {
    .nb-page-title {
        font-size: 2.15rem;
    }

    .nb-main,
    .nb-workspace .nb-main {
        padding: 22px 0 36px;
    }

    .nb-workspace-topbar {
        align-items: stretch;
        flex-direction: column;
    }

    .nb-search-shell input,
    .nb-mini-progress {
        width: 100%;
    }

    .nb-module-hero,
    .nb-continue-card,
    .nb-lesson-actions {
        align-items: stretch;
        flex-direction: column;
    }

    .nb-hero-progress {
        width: 100%;
        text-align: left;
    }

    .nb-side-nav {
        grid-template-columns: 1fr;
    }

    .nb-lesson-row {
        grid-template-columns: 14px minmax(0, 1fr);
    }

    .nb-lesson-meta {
        grid-column: 2;
    }
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
    }
}