:root {
    color-scheme: dark;
    --bg-dark: #0a0a0f;
    --bg-card: #12121a;
    --bg-code: #1a1a2e;
    --bg-overlay-strong: rgba(10, 10, 15, 0.92);
    --neon-cyan: #00f5ff;
    --neon-magenta: #ff00ff;
    --neon-purple: #b366ff;
    --text-primary: #ffffff;
    --text-secondary: #a0a0b0;
    --border-color: #2a2a3a;
    --success-green: #4ec9b0;
    --warning-yellow: #dcdcaa;
    --bg: var(--bg-dark);
    --bg-elevated: var(--bg-card);
    --surface: var(--bg-card);
    --surface-soft: var(--bg-code);
    --border: var(--border-color);
    --text: var(--text-primary);
    --muted: var(--text-secondary);
    --accent: var(--neon-cyan);
    --accent-strong: var(--neon-cyan);
    --accent-ink: var(--bg-dark);
    --violet: var(--neon-purple);
    --code-bg: var(--bg-code);
    --code-text: var(--text-primary);
    --focus: #ffd166;
    --danger: #ff8f8f;
    --shadow: 0 24px 80px rgba(0, 0, 0, 0.35);
    --font-sans: "Instrument Sans", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    --font-mono: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;
}

* {
    box-sizing: border-box;
}

[hidden] {
    display: none !important;
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
    border: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 8rem;
}

body {
    min-width: 320px;
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: var(--font-sans);
    line-height: 1.65;
}

body.navigation-open {
    overflow: hidden;
}

a {
    color: var(--accent);
    text-underline-offset: 0.18em;
}

button,
a {
    -webkit-tap-highlight-color: transparent;
}

button {
    font-family: inherit;
}

:focus-visible {
    outline: 3px solid var(--focus);
    outline-offset: 3px;
}

.skip-link {
    position: fixed;
    top: 0.75rem;
    left: 0.75rem;
    z-index: 100;
    padding: 0.65rem 0.9rem;
    border-radius: 0.5rem;
    background: var(--text);
    color: var(--bg);
    font-weight: 700;
    transform: translateY(-160%);
    transition: transform 150ms ease;
}

.skip-link:focus {
    transform: translateY(0);
}

.lesson-header {
    position: sticky;
    top: 0;
    z-index: 30;
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 0.9rem;
    align-items: center;
    min-height: 4.35rem;
    padding: 0.6rem max(1rem, calc((100vw - 1220px) / 2));
    border-bottom: 1px solid var(--border);
    background: color-mix(in srgb, var(--bg-elevated) 92%, transparent);
    backdrop-filter: blur(16px);
}

.icon-button,
.header-step-link {
    display: inline-flex;
    min-height: 2.35rem;
    align-items: center;
    justify-content: center;
    padding: 0.45rem 0.72rem;
    border: 1px solid var(--border);
    border-radius: 0.62rem;
    background: var(--surface);
    color: var(--muted);
    font-size: 0.78rem;
    font-weight: 700;
    text-decoration: none;
    cursor: pointer;
}

.icon-button:hover,
.header-step-link:hover {
    border-color: color-mix(in srgb, var(--accent) 55%, var(--border));
    color: var(--text);
}

.header-step-link.primary {
    border-color: var(--accent);
    background: var(--accent);
    color: var(--accent-ink);
}

.lesson-brand {
    display: inline-flex;
    min-width: 0;
    align-items: center;
    gap: 0.75rem;
    color: var(--text);
    text-decoration: none;
}

.brand-mark {
    display: inline-grid;
    width: 2rem;
    height: 2rem;
    flex: 0 0 auto;
    place-items: center;
    border: 1px solid color-mix(in srgb, var(--accent) 65%, var(--border));
    border-radius: 0.65rem;
    background: color-mix(in srgb, var(--accent) 12%, var(--surface));
    color: var(--accent);
    font-family: var(--font-mono);
    font-weight: 700;
}

.brand-copy {
    display: flex;
    min-width: 0;
    flex-direction: column;
    line-height: 1.2;
}

.brand-copy strong {
    font-size: 0.84rem;
}

.brand-copy span {
    overflow: hidden;
    color: var(--muted);
    font-size: 0.72rem;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.45rem;
}

.lesson-progress {
    position: sticky;
    top: 4.35rem;
    z-index: 24;
    display: grid;
    grid-template-columns: auto minmax(170px, 1fr);
    gap: 1rem;
    align-items: center;
    min-height: 2.75rem;
    padding: 0.45rem max(1rem, calc((100vw - 1220px) / 2));
    border-bottom: 1px solid var(--border);
    background: var(--bg-elevated);
}

.progress-copy {
    display: flex;
    gap: 0.65rem;
    align-items: center;
    color: var(--muted);
    font-family: var(--font-mono);
    font-size: 0.7rem;
}

#stepPosition {
    color: var(--text);
    font-weight: 600;
}

.progress-track {
    overflow: hidden;
    height: 0.34rem;
    border-radius: 999px;
    background: var(--surface-soft);
}

.progress-track span {
    display: block;
    width: 100%;
    height: 100%;
    border-radius: inherit;
    background: linear-gradient(90deg, var(--accent-strong), var(--violet));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 220ms ease;
}

.navigation-overlay {
    position: fixed;
    z-index: 49;
    inset: 0;
    background: rgba(0, 0, 0, 0.62);
    backdrop-filter: blur(3px);
}

.navigation-panel {
    position: fixed;
    z-index: 50;
    top: 0;
    left: 0;
    overflow-y: auto;
    width: min(92vw, 390px);
    height: 100dvh;
    padding: 1.1rem;
    border-right: 1px solid var(--border);
    background: var(--bg-elevated);
    box-shadow: var(--shadow);
}

.navigation-heading {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border);
}

.eyebrow {
    margin: 0 0 0.4rem;
    color: var(--accent);
    font-family: var(--font-mono);
    font-size: 0.65rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.navigation-heading h2 {
    margin: 0;
    font-size: 1rem;
}

.navigation-group {
    margin-top: 1.2rem;
}

.navigation-group h3 {
    margin: 0 0 0.45rem;
    color: var(--muted);
    font-family: var(--font-mono);
    font-size: 0.64rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.navigation-link {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    gap: 0.75rem;
    align-items: center;
    margin-bottom: 0.25rem;
    padding: 0.7rem;
    border: 1px solid transparent;
    border-radius: 0.7rem;
    color: var(--muted);
    text-decoration: none;
}

.navigation-link:hover {
    background: var(--surface);
    color: var(--text);
}

.navigation-link.active {
    border-color: color-mix(in srgb, var(--accent) 55%, var(--border));
    background: color-mix(in srgb, var(--accent) 8%, var(--surface));
    color: var(--text);
}

.navigation-marker {
    display: inline-grid;
    width: 1.8rem;
    height: 1.8rem;
    place-items: center;
    border: 1px solid var(--border);
    border-radius: 0.55rem;
    color: var(--accent);
    font-family: var(--font-mono);
    font-size: 0.7rem;
    font-weight: 600;
}

.navigation-link strong,
.navigation-link small {
    display: block;
}

.navigation-link strong {
    font-size: 0.83rem;
}

.navigation-link small {
    color: var(--muted);
    font-family: var(--font-mono);
    font-size: 0.65rem;
}

.lesson-shell {
    width: min(1180px, calc(100% - 2rem));
    margin: 0 auto;
    padding: 1.3rem 0 4rem;
}

.lesson-content {
    max-width: 900px;
    margin: 0 auto;
    padding: clamp(1.7rem, 4vw, 3.4rem) clamp(0rem, 2vw, 1rem) 0;
}

.loading-message {
    min-height: 40vh;
    color: var(--muted);
}

.markdown {
    font-size: 1rem;
}

.markdown h1,
.markdown h2,
.markdown h3,
.markdown h4 {
    color: var(--text);
    line-height: 1.18;
    letter-spacing: -0.025em;
}

.markdown h1 {
    margin: 0 0 1rem;
    font-size: clamp(2.25rem, 5vw, 3.7rem);
    letter-spacing: -0.05em;
}

.markdown h1 + blockquote {
    margin-top: 0;
}

.markdown h2 {
    margin: 3.2rem 0 1rem;
    padding-top: 0.9rem;
    border-top: 1px solid var(--border);
    font-size: clamp(1.45rem, 2.7vw, 2rem);
}

.markdown h3 {
    margin: 2rem 0 0.7rem;
    font-size: 1.2rem;
}

.markdown p,
.markdown li {
    color: color-mix(in srgb, var(--text) 88%, var(--muted));
}

.markdown p {
    margin: 0 0 1rem;
}

.markdown ul,
.markdown ol {
    margin: 0 0 1.2rem;
    padding-left: 1.4rem;
}

.markdown li {
    margin-bottom: 0.38rem;
}

.markdown strong {
    color: var(--text);
}

.markdown a:hover {
    color: var(--accent-strong);
}

.markdown blockquote {
    margin: 1.2rem 0;
    padding: 0.9rem 1rem;
    border: 1px solid color-mix(in srgb, var(--accent) 38%, var(--border));
    border-left: 0.28rem solid var(--accent);
    border-radius: 0.7rem;
    background: color-mix(in srgb, var(--accent) 7%, var(--surface));
}

.markdown blockquote p:last-child {
    margin-bottom: 0;
}

.markdown :not(pre) > code {
    padding: 0.12rem 0.36rem;
    border: 1px solid var(--border);
    border-radius: 0.32rem;
    background: var(--surface-soft);
    color: var(--violet);
    font-family: var(--font-mono);
    font-size: 0.84em;
}

.markdown pre {
    position: relative;
    overflow: auto;
    margin: 1rem 0 1.4rem;
    padding: 2.8rem 1rem 1rem;
    border: 1px solid var(--border);
    border-radius: 0.78rem;
    background: var(--code-bg);
    box-shadow: 0 14px 40px rgba(0, 0, 0, 0.16);
}

.markdown pre::before {
    position: absolute;
    top: 0.8rem;
    left: 1rem;
    color: #8390a5;
    content: "code";
    font-family: var(--font-mono);
    font-size: 0.62rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.markdown pre code,
.markdown pre code.hljs {
    display: block;
    overflow: visible;
    padding: 0;
    background: transparent;
    color: var(--code-text);
    font-family: var(--font-mono);
    font-size: 0.8rem;
    line-height: 1.68;
    white-space: pre;
}

.copy-code-button {
    position: absolute;
    top: 0.55rem;
    right: 0.55rem;
    min-width: 3.7rem;
    padding: 0.32rem 0.55rem;
    border: 1px solid #3d485c;
    border-radius: 0.42rem;
    background: #151c29;
    color: #c6cfdd;
    font-family: var(--font-sans);
    font-size: 0.67rem;
    font-weight: 700;
    cursor: pointer;
}

.copy-code-button:hover {
    border-color: var(--accent);
    color: #ffffff;
}

.copy-code-button.copied {
    border-color: var(--accent-strong);
    color: var(--accent);
}

.copy-code-button.copy-error {
    border-color: var(--danger);
    color: var(--danger);
}

.markdown table {
    display: block;
    overflow-x: auto;
    width: 100%;
    margin: 1.1rem 0 1.5rem;
    border-spacing: 0;
    border-collapse: separate;
    border: 1px solid var(--border);
    border-radius: 0.72rem;
}

.markdown th,
.markdown td {
    min-width: 150px;
    padding: 0.75rem 0.85rem;
    border-right: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    text-align: left;
    vertical-align: top;
}

.markdown th {
    background: var(--surface-soft);
    color: var(--text);
    font-size: 0.78rem;
}

.markdown td {
    color: color-mix(in srgb, var(--text) 84%, var(--muted));
    font-size: 0.86rem;
}

.markdown tr:last-child td {
    border-bottom: 0;
}

.markdown th:last-child,
.markdown td:last-child {
    border-right: 0;
}

.markdown details {
    margin: 1.1rem 0;
    border: 1px solid var(--border);
    border-radius: 0.72rem;
    background: var(--bg-elevated);
}

.markdown summary {
    padding: 0.85rem 1rem;
    color: var(--text);
    font-weight: 700;
    cursor: pointer;
}

.markdown summary:hover {
    color: var(--accent);
}

.markdown details[open] > summary {
    border-bottom: 1px solid var(--border);
}

.markdown details > :not(summary) {
    margin-right: 1rem;
    margin-left: 1rem;
}

.markdown details > pre {
    margin-right: 0.8rem;
    margin-left: 0.8rem;
}

.workshop-tabs {
    margin: 1rem 0 1.4rem;
}

.workshop-tabs [role="tablist"] {
    display: flex;
    gap: 0.3rem;
    overflow-x: auto;
    padding: 0.3rem;
    border: 1px solid var(--border);
    border-bottom: 0;
    border-radius: 0.72rem 0.72rem 0 0;
    background: var(--surface-soft);
}

.workshop-tabs [role="tab"] {
    flex: 0 0 auto;
    padding: 0.48rem 0.75rem;
    border: 1px solid transparent;
    border-radius: 0.48rem;
    background: transparent;
    color: var(--muted);
    font-size: 0.78rem;
    font-weight: 700;
    cursor: pointer;
}

.workshop-tabs [role="tab"][aria-selected="true"] {
    border-color: var(--border);
    background: var(--surface);
    color: var(--text);
}

.workshop-tabs [role="tabpanel"] {
    padding: 0.2rem 0.8rem;
    border: 1px solid var(--border);
    border-radius: 0 0 0.72rem 0.72rem;
    background: var(--bg-elevated);
}

.workshop-tabs [role="tabpanel"] pre {
    margin: 0.7rem 0;
}

.lesson-footer {
    display: flex;
    gap: 1rem;
    margin-top: 4rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border);
}

.footer-link {
    display: flex;
    min-width: min(46%, 300px);
    flex-direction: column;
    padding: 0.85rem 1rem;
    border: 1px solid var(--border);
    border-radius: 0.72rem;
    background: var(--bg-elevated);
    color: var(--text);
    text-decoration: none;
}

.footer-link:hover {
    border-color: var(--accent);
}

.footer-link small {
    color: var(--muted);
    font-family: var(--font-mono);
    font-size: 0.65rem;
    text-transform: uppercase;
}

.footer-link strong {
    font-size: 0.83rem;
}

.footer-link.next {
    margin-left: auto;
    text-align: right;
}

.load-error {
    padding: 1.2rem;
    border: 1px solid color-mix(in srgb, var(--danger) 65%, var(--border));
    border-radius: 0.8rem;
    background: color-mix(in srgb, var(--danger) 8%, var(--surface));
}

.load-error h1 {
    font-size: 1.7rem;
}

@media (max-width: 700px) {
    html {
        scroll-padding-top: 7rem;
    }

    .lesson-header {
        min-height: 3.8rem;
        gap: 0.55rem;
        padding: 0.45rem 0.65rem;
    }

    .brand-mark {
        width: 1.8rem;
        height: 1.8rem;
    }

    .brand-copy strong {
        font-size: 0.75rem;
    }

    .brand-copy span,
    .header-step-link:not(.primary) {
        display: none;
    }

    .header-actions {
        gap: 0.3rem;
    }

    .theme-toggle,
    .header-step-link,
    .icon-button {
        min-height: 2.1rem;
        padding: 0.35rem 0.5rem;
        font-size: 0.68rem;
    }

    .lesson-progress {
        top: 3.8rem;
        grid-template-columns: auto minmax(70px, 1fr);
        min-height: 2.35rem;
        padding: 0.35rem 0.7rem;
    }

    .lesson-shell {
        width: min(100% - 1rem, 1180px);
        padding-top: 0.65rem;
    }

    .lesson-content {
        padding-top: 1.5rem;
    }

    .markdown h1 {
        font-size: clamp(2rem, 11vw, 3rem);
    }

    .markdown h2 {
        margin-top: 2.6rem;
    }

    .markdown pre {
        margin-right: -0.15rem;
        margin-left: -0.15rem;
    }

    .lesson-footer {
        flex-direction: column;
    }

    .footer-link {
        width: 100%;
        min-width: 0;
    }

    .footer-link.next {
        margin-left: 0;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
        transition-duration: 0.01ms !important;
    }
}

.workshop-complete h1 {
    color: var(--accent);
    letter-spacing: -0.03em;
    text-wrap: balance;
}

.workshop-complete > p:first-of-type {
    max-width: 65ch;
    font-size: clamp(1.1rem, 2vw, 1.3rem);
}

.completion-confetti {
    position: fixed;
    z-index: 110;
    inset: 0;
    overflow: hidden;
    pointer-events: none;
}

.completion-confetti span {
    position: absolute;
    top: -1rem;
    width: 0.45rem;
    height: 0.8rem;
    background: var(--accent);
    animation: completion-confetti-fall 2800ms cubic-bezier(0.16, 1, 0.3, 1) var(--delay) both;
}

.completion-confetti span:nth-child(3n) {
    background: var(--violet);
}

.completion-confetti span:nth-child(3n + 1) {
    background: var(--success-green);
}

@keyframes completion-confetti-fall {
    from {
        transform: translate3d(0, 0, 0) rotate(0);
        opacity: 1;
    }
    to {
        transform: translate3d(var(--drift), calc(100vh + 2rem), 0) rotate(var(--turn));
        opacity: 0;
    }
}

@media (prefers-reduced-motion: reduce) {
    .completion-confetti {
        display: none;
    }

    .completion-confetti span {
        animation: none;
    }
}

/* Upstream workshop shell with the rebuilt curriculum behavior. */
.header {
    position: sticky;
    z-index: 100;
    top: 0;
    padding: 0 2rem;
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-card);
}

/* The progress bar and step list stick below the header, so its height is fixed. */
.header-content {
    display: flex;
    max-width: 1400px;
    min-height: 64px;
    align-items: center;
    gap: 0.5rem;
    margin: 0 auto;
}

.header-brand {
    display: flex;
    min-width: 0;
    flex: 1 1 auto;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-primary);
    text-decoration: none;
}

.header-brand:hover {
    color: var(--neon-cyan);
}

.header-icon {
    width: 1.5rem;
    height: 1.5rem;
    flex: 0 0 auto;
    fill: currentColor;
}

.header-title {
    overflow: hidden;
    color: var(--neon-cyan);
    font-size: 1.25rem;
    font-weight: 600;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.header-nav {
    display: flex;
    flex: 0 0 auto;
    align-items: center;
    gap: 0.5rem;
}

.nav-btn {
    display: inline-flex;
    min-height: 2.5rem;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: transparent;
    color: var(--text-secondary);
    font: inherit;
    font-size: 0.875rem;
    text-decoration: none;
    white-space: nowrap;
    cursor: pointer;
    transition: all 0.2s ease;
}

.nav-btn:hover:not(:disabled) {
    border-color: var(--neon-cyan);
    color: var(--neon-cyan);
}

.menu-btn {
    display: none;
    width: 2.5rem;
    flex: 0 0 auto;
    padding: 0;
}

.menu-btn svg,
.flyout-close svg {
    width: 1.15rem;
    height: 1.15rem;
    fill: none;
    stroke: currentColor;
    stroke-width: 1.75;
    stroke-linecap: round;
}

.lesson-progress {
    top: 65px;
    z-index: 90;
    border-bottom-color: var(--border-color);
    background: color-mix(in srgb, var(--bg-card) 94%, transparent);
}

.progress-track {
    background: var(--bg-code);
}

.progress-track span {
    background: linear-gradient(90deg, var(--neon-cyan), var(--neon-magenta));
}

.layout {
    display: flex;
    max-width: 1400px;
    align-items: flex-start;
    margin: 0 auto;
}

.main {
    min-width: 0;
    flex: 1;
    padding: 1.3rem 3rem 4rem;
}

.lesson-shell {
    width: min(100%, 1080px);
    padding: 0;
}

.flyout-overlay {
    display: none;
}

.flyout-panel {
    position: sticky;
    top: 110px;
    z-index: 50;
    display: flex;
    overflow-y: auto;
    width: 280px;
    height: calc(100vh - 110px);
    min-height: calc(100vh - 110px);
    flex: 0 0 auto;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
    background: var(--bg-card);
}

.flyout-header {
    position: sticky;
    z-index: 1;
    top: 0;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.25rem;
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-card);
}

.flyout-title {
    font-size: 1rem;
    font-weight: 600;
}

.flyout-close {
    display: none;
}

.flyout-nav {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    padding: 1rem;
}

.navigation-group {
    margin-top: 0.65rem;
}

.navigation-group:first-child {
    margin-top: 0;
}

.navigation-group h3 {
    margin: 0 0 0.45rem;
    padding: 0 0.45rem;
    color: var(--text-secondary);
    font-family: var(--font-mono);
    font-size: 0.64rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.flyout-link {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.625rem 0.75rem;
    border-radius: 6px;
    color: var(--text-secondary);
    font-size: 0.875rem;
    text-decoration: none;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.flyout-link:hover {
    background: rgba(0, 245, 255, 0.1);
    color: var(--text-primary);
}

.flyout-link.active {
    background: rgba(0, 245, 255, 0.16);
    color: var(--text-primary);
}

.flyout-number {
    display: flex;
    width: 28px;
    height: 28px;
    flex: 0 0 auto;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    background: var(--border-color);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 600;
}

.flyout-link.active .flyout-number {
    background: linear-gradient(135deg, var(--neon-cyan), var(--neon-magenta));
    color: var(--bg-dark);
}

.flyout-link strong,
.flyout-link small {
    display: block;
}

.flyout-link strong {
    color: inherit;
    font-size: 0.83rem;
}

.flyout-link small {
    color: var(--text-secondary);
    font-family: var(--font-mono);
    font-size: 0.65rem;
}

.markdown h1 {
    color: var(--text-primary);
}

.markdown h2 {
    padding-top: 0;
    padding-bottom: 0.5rem;
    border-top: 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--neon-cyan);
}

.markdown h3 {
    color: var(--neon-magenta);
}

.markdown blockquote {
    border-color: color-mix(in srgb, var(--neon-cyan) 38%, var(--border-color));
    border-left-color: var(--neon-cyan);
    background: rgba(0, 245, 255, 0.05);
}

.copy-code-button:hover {
    border-color: var(--neon-cyan);
}

.nav-footer {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.nav-footer-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-primary);
    font-weight: 500;
    text-decoration: none;
    transition: all 0.2s ease;
}

.nav-footer-btn:hover {
    border-color: var(--neon-cyan);
    transform: translateY(-2px);
}

.nav-footer-btn.disabled {
    opacity: 0.4;
}

.lesson-content .site-footer {
    margin-top: 2.5rem;
    padding-top: 1.25rem;
}

@media (max-width: 900px) {
    .menu-btn {
        display: inline-flex;
    }

    .flyout-overlay {
        position: fixed;
        z-index: 190;
        inset: 0;
        display: block;
        background: rgba(0, 0, 0, 0.62);
        opacity: 0;
        pointer-events: none;
        transition: opacity 0.2s ease;
    }

    .flyout-overlay.open {
        opacity: 1;
        pointer-events: auto;
    }

    .flyout-panel {
        position: fixed;
        z-index: 200;
        top: 0;
        left: 0;
        width: min(88vw, 320px);
        height: 100dvh;
        min-height: 100dvh;
        transform: translateX(-100%);
        transition: transform 0.25s ease;
    }

    .flyout-panel.open {
        transform: translateX(0);
    }

    .flyout-close {
        display: inline-flex;
        width: 32px;
        height: 32px;
        align-items: center;
        justify-content: center;
        border: 1px solid var(--border-color);
        border-radius: 6px;
        background: transparent;
        color: var(--text-secondary);
        font-size: 1rem;
        cursor: pointer;
    }

    .flyout-close:hover {
        border-color: var(--neon-cyan);
        color: var(--neon-cyan);
    }

    .main {
        width: 100%;
        padding: 1rem 1.25rem 4rem;
    }

    .layout {
        max-width: none;
    }
}

@media (max-width: 700px) {
    .header {
        padding: 0 0.75rem;
    }

    .header-content {
        gap: 0.5rem;
    }

    .header-brand {
        gap: 0.4rem;
    }

    .header-content {
        min-height: 57px;
    }

    .header-title {
        font-size: 1rem;
    }

    #previousHeaderLink {
        display: none;
    }

    .nav-btn {
        padding: 0.4rem 0.7rem;
        font-size: 0.8rem;
    }

    .lesson-progress {
        top: 58px;
    }

    .nav-footer {
        flex-direction: column;
    }

    .nav-footer-btn {
        width: 100%;
        justify-content: center;
    }
}

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