:root {
    color-scheme: dark;
    --page: #08101f;
    --page-soft: #0c1628;
    --panel: #111d31;
    --panel-raised: #17253d;
    --panel-soft: #1d2d48;
    --text: #eef4ff;
    --muted: #9babc8;
    --subtle: #71809e;
    --line: rgba(155, 171, 200, 0.2);
    --line-strong: rgba(155, 171, 200, 0.38);
    --accent: #70e1b2;
    --accent-dark: #082e26;
    --blue: #78aefc;
    --amber: #ffc66d;
    --danger: #ff8e9c;
    --success: #70e1b2;
    --shadow: 0 24px 70px rgba(0, 0, 0, 0.3);
    --editor-scale: 1;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
    box-sizing: border-box;
}

html {
    min-width: 320px;
    min-height: 100%;
    background: var(--page);
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    margin: 0;
    color: var(--text);
    background:
        radial-gradient(circle at 78% -5%, rgba(53, 116, 195, 0.2), transparent 28rem),
        radial-gradient(circle at 5% 20%, rgba(112, 225, 178, 0.08), transparent 25rem),
        var(--page);
}

button,
input,
select,
textarea {
    font: inherit;
}

button,
select,
input,
textarea,
a {
    outline-offset: 3px;
}

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

a {
    color: inherit;
}

button {
    color: inherit;
}

h1,
h2,
h3,
p,
ul,
ol,
dl {
    margin-top: 0;
}

h1,
h2,
h3 {
    letter-spacing: -0.025em;
    text-wrap: balance;
}

p,
li {
    text-wrap: pretty;
}

.assessment-site {
    min-height: 100vh;
}

.assessment-site.high-contrast {
    --page: #000;
    --page-soft: #050505;
    --panel: #0b0b0b;
    --panel-raised: #121212;
    --panel-soft: #1b1b1b;
    --text: #fff;
    --muted: #e2e2e2;
    --subtle: #c9c9c9;
    --line: rgba(255, 255, 255, 0.45);
    --line-strong: rgba(255, 255, 255, 0.75);
    --accent: #7dffc9;
    --blue: #9fc3ff;
    --amber: #ffe071;
    --danger: #ff9fab;
}

.skip-link {
    position: fixed;
    top: 0.8rem;
    left: 0.8rem;
    z-index: 100;
    padding: 0.75rem 1rem;
    color: #061610;
    background: var(--accent);
    border-radius: 0.5rem;
    transform: translateY(-160%);
}

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

.site-header {
    position: relative;
    z-index: 10;
    display: flex;
    gap: 1.5rem;
    align-items: center;
    width: min(1440px, calc(100% - 3rem));
    min-height: 76px;
    margin: 0 auto;
    border-bottom: 1px solid var(--line);
}

.brand {
    display: inline-flex;
    gap: 0.75rem;
    align-items: center;
    margin-right: auto;
    text-decoration: none;
}

.brand-mark {
    display: grid;
    width: 2.35rem;
    height: 2.35rem;
    place-items: center;
    color: #061610;
    background: var(--accent);
    border-radius: 0.65rem;
    font: 800 0.82rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.brand strong,
.brand small {
    display: block;
}

.brand strong {
    font-size: 0.96rem;
}

.brand small {
    margin-top: 0.15rem;
    color: var(--muted);
    font-size: 0.72rem;
}

.site-nav {
    display: flex;
    gap: 0.35rem;
    align-items: center;
}

.site-nav a {
    padding: 0.62rem 0.78rem;
    color: var(--muted);
    border-radius: 0.5rem;
    font-size: 0.88rem;
    font-weight: 650;
    text-decoration: none;
}

.site-nav a:hover,
.site-nav a.active {
    color: var(--text);
    background: var(--panel-raised);
}

.mode-badge,
.difficulty,
.command-label {
    display: inline-flex;
    align-items: center;
    width: fit-content;
    padding: 0.28rem 0.5rem;
    border: 1px solid var(--line-strong);
    border-radius: 999px;
    font: 700 0.68rem/1.2 ui-monospace, SFMono-Regular, Consolas, monospace;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.mode-practice {
    color: var(--accent);
    border-color: rgba(112, 225, 178, 0.42);
}

.mode-assessment {
    color: var(--amber);
    border-color: rgba(255, 198, 109, 0.45);
}

.page-shell {
    width: min(1240px, calc(100% - 3rem));
    margin: 0 auto;
}

.narrow-shell {
    width: min(960px, calc(100% - 3rem));
}

.catalog-hero {
    display: grid;
    grid-template-columns: minmax(0, 1.55fr) minmax(270px, 0.65fr);
    gap: clamp(2rem, 6vw, 6rem);
    align-items: center;
    min-height: 540px;
    padding: 5rem 0;
}

.eyebrow {
    margin-bottom: 0.8rem;
    color: var(--accent);
    font: 750 0.72rem/1.4 ui-monospace, SFMono-Regular, Consolas, monospace;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.catalog-hero h1,
.page-intro h1 {
    max-width: 880px;
    margin-bottom: 1.35rem;
    font-size: clamp(2.5rem, 6vw, 5rem);
    line-height: 0.99;
}

.hero-copy,
.page-intro > p:last-child {
    max-width: 780px;
    color: var(--muted);
    font-size: clamp(1rem, 2vw, 1.22rem);
    line-height: 1.65;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 2rem;
}

.button {
    display: inline-flex;
    gap: 0.5rem;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    padding: 0.72rem 1rem;
    border: 1px solid transparent;
    border-radius: 0.55rem;
    font-size: 0.86rem;
    font-weight: 750;
    line-height: 1.2;
    text-decoration: none;
    cursor: pointer;
}

.button.primary {
    color: #07150f;
    background: var(--accent);
}

.button.primary:hover {
    filter: brightness(1.08);
}

.button.secondary {
    color: var(--text);
    background: var(--panel-raised);
    border-color: var(--line);
}

.button.ghost {
    color: var(--muted);
    background: transparent;
    border-color: var(--line);
}

.button.danger {
    color: var(--danger);
    background: rgba(255, 142, 156, 0.08);
    border-color: rgba(255, 142, 156, 0.3);
}

.button.compact {
    min-height: 38px;
    padding: 0.55rem 0.75rem;
    font-size: 0.78rem;
}

.button:disabled {
    opacity: 0.48;
    cursor: not-allowed;
}

.environment-card {
    padding: 1.5rem;
    background: linear-gradient(145deg, rgba(29, 45, 72, 0.9), rgba(17, 29, 49, 0.94));
    border: 1px solid var(--line-strong);
    border-radius: 1rem;
    box-shadow: var(--shadow);
}

.status-dot {
    display: inline-block;
    width: 0.55rem;
    height: 0.55rem;
    margin-right: 0.5rem;
    background: var(--success);
    border-radius: 50%;
    box-shadow: 0 0 0 5px rgba(112, 225, 178, 0.1);
}

.environment-card dl {
    margin: 1.5rem 0 0;
}

.environment-card dl div {
    display: flex;
    justify-content: space-between;
    padding: 0.7rem 0;
    border-top: 1px solid var(--line);
}

.environment-card dt {
    color: var(--muted);
}

.environment-card dd {
    margin: 0;
    font: 650 0.8rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
    text-transform: capitalize;
}

.principles-grid,
.runtime-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    border: 1px solid var(--line);
    border-radius: 0.9rem;
    overflow: hidden;
}

.principles-grid article,
.runtime-grid article {
    min-width: 0;
    padding: 1.35rem;
    background: rgba(17, 29, 49, 0.72);
    border-right: 1px solid var(--line);
}

.principles-grid article:last-child,
.runtime-grid article:last-child {
    border-right: 0;
}

.principles-grid span,
.runtime-grid span {
    color: var(--accent);
    font: 700 0.7rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.principles-grid h2,
.runtime-grid h3 {
    margin: 1rem 0 0.5rem;
    font-size: 1rem;
}

.principles-grid p,
.runtime-grid p {
    margin: 0;
    color: var(--muted);
    font-size: 0.85rem;
    line-height: 1.55;
}

.catalog-section,
.runtime-section,
.history-section {
    padding: 6rem 0 0;
}

.section-heading {
    display: flex;
    gap: 1rem;
    align-items: end;
    justify-content: space-between;
    margin-bottom: 1.5rem;
}

.section-heading h2,
.runtime-section h2,
.preflight-finish h2 {
    margin-bottom: 0;
    font-size: clamp(1.7rem, 4vw, 2.6rem);
}

.section-heading > p {
    margin: 0;
    color: var(--muted);
    font-size: 0.86rem;
}

.challenge-list {
    display: grid;
    gap: 0.8rem;
}

.challenge-card {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 1.2rem;
    align-items: center;
    padding: 1.4rem;
    background: rgba(17, 29, 49, 0.76);
    border: 1px solid var(--line);
    border-radius: 0.8rem;
    transition: border-color 140ms ease, transform 140ms ease;
}

.challenge-card:hover {
    border-color: var(--line-strong);
    transform: translateY(-2px);
}

.challenge-index {
    align-self: start;
    color: var(--subtle);
    font: 700 0.75rem/1.4 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.challenge-meta,
.skill-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.55rem;
    align-items: center;
}

.challenge-meta {
    color: var(--subtle);
    font: 650 0.69rem/1.3 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.difficulty-foundation {
    color: var(--accent);
}

.difficulty-intermediate {
    color: var(--blue);
}

.difficulty-advanced {
    color: var(--amber);
}

.challenge-main h3 {
    margin: 0.8rem 0 0.45rem;
    font-size: 1.25rem;
}

.challenge-main > p {
    max-width: 780px;
    margin-bottom: 0.9rem;
    color: var(--muted);
    line-height: 1.55;
}

.skill-list {
    margin-bottom: 0;
    padding: 0;
    list-style: none;
}

.skill-list li {
    padding: 0.25rem 0.45rem;
    color: var(--muted);
    background: var(--panel-raised);
    border-radius: 0.32rem;
    font-size: 0.7rem;
}

.challenge-action {
    display: grid;
    gap: 0.7rem;
    justify-items: end;
    min-width: 130px;
}

.challenge-action p {
    margin: 0;
    text-align: right;
}

.challenge-action strong,
.challenge-action small {
    display: block;
}

.challenge-action strong {
    color: var(--accent);
    font: 750 1.2rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.challenge-action small {
    margin-top: 0.2rem;
    color: var(--muted);
    font-size: 0.65rem;
}

.runtime-section {
    display: grid;
    grid-template-columns: 0.55fr 1.45fr;
    gap: 3rem;
    align-items: start;
}

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

.runtime-grid article:nth-child(2) {
    border-right: 0;
}

.runtime-grid article:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line);
}

.history-table-wrap {
    overflow-x: auto;
    border: 1px solid var(--line);
    border-radius: 0.8rem;
}

table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

th,
td {
    padding: 0.9rem 1rem;
    border-bottom: 1px solid var(--line);
}

th {
    color: var(--subtle);
    font: 700 0.68rem/1.3 ui-monospace, SFMono-Regular, Consolas, monospace;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

td {
    color: var(--muted);
    font-size: 0.82rem;
}

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

td strong {
    color: var(--text);
}

.site-footer {
    width: min(1240px, calc(100% - 3rem));
    margin: 6rem auto 0;
    padding: 2rem 0;
    color: var(--subtle);
    border-top: 1px solid var(--line);
    font-size: 0.75rem;
}

.site-footer p {
    margin: 0;
}

.page-intro {
    padding: 5rem 0 3rem;
    border-bottom: 1px solid var(--line);
}

.page-intro h1 {
    max-width: 850px;
    font-size: clamp(2.3rem, 6vw, 4.4rem);
}

.tutorial-section {
    display: grid;
    grid-template-columns: 3rem minmax(0, 1fr);
    gap: 1.5rem;
    padding: 3.5rem 0;
    border-bottom: 1px solid var(--line);
}

.step-number {
    display: grid;
    width: 2.25rem;
    height: 2.25rem;
    place-items: center;
    color: var(--accent);
    background: var(--accent-dark);
    border: 1px solid rgba(112, 225, 178, 0.3);
    border-radius: 50%;
    font: 750 0.75rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.tutorial-section h2 {
    margin-bottom: 0.7rem;
    font-size: 1.65rem;
}

.tutorial-section > div > p {
    color: var(--muted);
    line-height: 1.65;
}

.choice-grid,
.comparison-grid,
.settings-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.8rem;
    margin-top: 1.5rem;
}

.choice-card,
.comparison-grid article,
.settings-grid > label {
    padding: 1.1rem;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 0.7rem;
}

.choice-card {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    gap: 0.45rem 0.75rem;
    cursor: pointer;
}

.choice-card.selected {
    background: rgba(112, 225, 178, 0.08);
    border-color: rgba(112, 225, 178, 0.55);
}

.choice-card input {
    grid-row: 1 / span 2;
    accent-color: var(--accent);
}

.choice-card > span:last-child {
    color: var(--muted);
    font-size: 0.82rem;
    line-height: 1.5;
}

.choice-title {
    font-weight: 750;
}

.settings-grid > label {
    display: grid;
    gap: 0.55rem;
    color: var(--muted);
    font-size: 0.8rem;
}

.settings-grid select,
.workspace-select {
    width: 100%;
    min-height: 42px;
    padding: 0.55rem 0.7rem;
    color: var(--text);
    background: var(--page-soft);
    border: 1px solid var(--line-strong);
    border-radius: 0.45rem;
}

.settings-grid .toggle-setting {
    grid-column: 1 / -1;
    display: flex;
    flex-direction: row;
    gap: 0.7rem;
    align-items: center;
}

.toggle-setting input {
    width: 1.1rem;
    height: 1.1rem;
    accent-color: var(--accent);
}

.comparison-grid article h3 {
    margin: 1rem 0 0.5rem;
    font-size: 1rem;
}

.comparison-grid article p {
    margin: 0;
    color: var(--muted);
    font-size: 0.84rem;
    line-height: 1.55;
}

.command-label {
    color: var(--blue);
}

.notice {
    margin-top: 1rem;
    padding: 0.9rem 1rem;
    background: rgba(255, 198, 109, 0.07);
    border-left: 3px solid var(--amber);
}

.notice strong {
    color: var(--amber);
}

.notice .button {
    margin-left: 0.75rem;
}

.capability-list {
    display: grid;
    gap: 0.6rem;
    margin: 1.5rem 0;
    padding: 0;
    list-style: none;
}

.capability-list li {
    display: flex;
    gap: 0.8rem;
    align-items: center;
    padding: 0.9rem 1rem;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 0.6rem;
}

.capability-list li > span {
    display: grid;
    width: 1.7rem;
    height: 1.7rem;
    flex: 0 0 auto;
    place-items: center;
    border-radius: 50%;
    font-weight: 800;
}

.capability-list .ready > span {
    color: #061610;
    background: var(--success);
}

.capability-list .blocked > span {
    color: #26050b;
    background: var(--danger);
}

.capability-list .checking > span {
    color: #211604;
    background: var(--amber);
}

.capability-list li > div {
    flex: 1;
}

.capability-list strong,
.capability-list small {
    display: block;
}

.capability-list small {
    margin-top: 0.2rem;
    color: var(--muted);
}

.capability-list .button {
    margin-top: 0.65rem;
}

.preflight-runner-frame {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip-path: inset(50%);
    border: 0;
}

.preflight-finish {
    display: flex;
    gap: 2rem;
    align-items: center;
    justify-content: space-between;
    margin-top: 3.5rem;
    padding: 2rem;
    background: linear-gradient(130deg, rgba(112, 225, 178, 0.13), rgba(120, 174, 252, 0.09));
    border: 1px solid rgba(112, 225, 178, 0.3);
    border-radius: 1rem;
}

.preflight-finish p:last-child {
    max-width: 600px;
    margin: 0.6rem 0 0;
    color: var(--muted);
}

/* Challenge workspace */
.workspace-page {
    width: min(1800px, calc(100% - 2rem));
    margin: 0 auto;
    padding-bottom: 2rem;
}

.workspace-header {
    display: flex;
    gap: 1rem;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
}

.workspace-title {
    min-width: 0;
}

.workspace-title a {
    color: var(--muted);
    font-size: 0.74rem;
    text-decoration: none;
}

.workspace-title h1 {
    margin: 0.3rem 0 0;
    overflow: hidden;
    font-size: clamp(1.2rem, 2vw, 1.65rem);
    text-overflow: ellipsis;
    white-space: nowrap;
}

.workspace-header-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.65rem;
    align-items: center;
    justify-content: flex-end;
}

.timer-card {
    display: flex;
    gap: 0.65rem;
    align-items: center;
    padding: 0.5rem 0.7rem;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 0.5rem;
}

.timer-card span {
    color: var(--muted);
    font-size: 0.68rem;
}

.timer-card strong {
    font: 750 0.86rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.timer-card.over-time strong {
    color: var(--amber);
}

.save-state {
    color: var(--subtle);
    font-size: 0.7rem;
}

.workspace-levels {
    display: flex;
    gap: 0.45rem;
    overflow-x: auto;
    padding: 0 0 0.8rem;
}

.workspace-levels a {
    flex: 0 0 auto;
    padding: 0.48rem 0.7rem;
    color: var(--muted);
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 0.45rem;
    font-size: 0.72rem;
    font-weight: 700;
    text-decoration: none;
}

.workspace-levels a.active {
    color: var(--page);
    background: var(--accent);
    border-color: var(--accent);
}

.workspace-grid {
    display: grid;
    grid-template-columns: minmax(240px, 0.7fr) minmax(420px, 1.7fr) minmax(270px, 0.8fr);
    gap: 0.75rem;
    align-items: start;
}

.workspace-panel {
    min-width: 0;
    background: rgba(17, 29, 49, 0.92);
    border: 1px solid var(--line);
    border-radius: 0.7rem;
    overflow: hidden;
}

.panel-heading,
.editor-toolbar,
.runner-heading {
    display: flex;
    gap: 0.7rem;
    align-items: center;
    justify-content: space-between;
    min-height: 46px;
    padding: 0.7rem 0.85rem;
    border-bottom: 1px solid var(--line);
}

.panel-heading h2,
.runner-heading h2 {
    margin: 0;
    font-size: 0.86rem;
}

.panel-tabs {
    display: flex;
    gap: 0.25rem;
    padding: 0.45rem;
    border-bottom: 1px solid var(--line);
}

.panel-tabs button {
    flex: 1;
    padding: 0.5rem 0.45rem;
    color: var(--muted);
    background: transparent;
    border: 0;
    border-radius: 0.35rem;
    font-size: 0.7rem;
    font-weight: 700;
    cursor: pointer;
}

.panel-tabs button.active {
    color: var(--text);
    background: var(--panel-soft);
}

.panel-scroll {
    max-height: min(68vh, 820px);
    padding: 1rem;
    overflow: auto;
}

.brief-content {
    color: var(--muted);
    font-size: 0.84rem;
    line-height: 1.65;
    white-space: pre-wrap;
}

.policy-card,
.score-card,
.hint-card,
.review-card {
    margin-top: 1rem;
    padding: 0.85rem;
    background: var(--panel-raised);
    border: 1px solid var(--line);
    border-radius: 0.55rem;
}

.policy-card h3,
.score-card h3,
.hint-card h3,
.review-card h3 {
    margin-bottom: 0.45rem;
    font-size: 0.8rem;
}

.policy-card p,
.score-card p,
.hint-card p,
.review-card p {
    margin-bottom: 0.5rem;
    color: var(--muted);
    font-size: 0.75rem;
    line-height: 1.5;
}

.policy-card ul,
.score-card ul,
.review-card ul {
    margin-bottom: 0;
    padding-left: 1.15rem;
    color: var(--muted);
    font-size: 0.74rem;
    line-height: 1.55;
}

.notes-field {
    display: grid;
    gap: 0.5rem;
    color: var(--muted);
    font-size: 0.74rem;
}

.notes-field textarea {
    width: 100%;
    min-height: 180px;
    padding: 0.7rem;
    resize: vertical;
    color: var(--text);
    background: var(--page-soft);
    border: 1px solid var(--line-strong);
    border-radius: 0.45rem;
    line-height: 1.5;
}

.file-explorer {
    display: flex;
    gap: 0.3rem;
    align-items: stretch;
    padding: 0.45rem;
    overflow-x: auto;
    border-bottom: 1px solid var(--line);
}

.file-button {
    display: inline-flex;
    gap: 0.4rem;
    align-items: center;
    flex: 0 0 auto;
    padding: 0.5rem 0.65rem;
    color: var(--muted);
    background: transparent;
    border: 1px solid transparent;
    border-radius: 0.35rem;
    font: 600 0.7rem/1.2 ui-monospace, SFMono-Regular, Consolas, monospace;
    cursor: pointer;
}

.file-button.active {
    color: var(--text);
    background: var(--panel-soft);
    border-color: var(--line);
}

.file-button .modified-dot {
    width: 0.38rem;
    height: 0.38rem;
    background: var(--amber);
    border-radius: 50%;
}

.editor-toolbar {
    min-height: 40px;
    padding-block: 0.5rem;
    color: var(--subtle);
    font: 600 0.68rem/1.2 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.editor-toolbar span:last-child {
    color: var(--muted);
}

.assessment-editor {
    min-height: 540px;
    font-size: calc(0.88rem * var(--editor-scale));
}

.assessment-editor .cm-editor {
    min-height: 540px;
    color: #dce7ff;
    background: #0a1221;
}

.assessment-editor .cm-scroller {
    min-height: 540px;
    overflow: auto;
    font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
    line-height: 1.55;
}

.assessment-editor .cm-gutters {
    color: #63728e;
    background: #0d1728;
    border-right-color: var(--line);
}

.assessment-editor .cm-activeLine,
.assessment-editor .cm-activeLineGutter {
    background: rgba(120, 174, 252, 0.08);
}

.assessment-editor .cm-selectionBackground,
.assessment-editor .cm-content ::selection {
    background: rgba(120, 174, 252, 0.3) !important;
}

.action-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 0.55rem;
    align-items: center;
    padding: 0.75rem;
    border-top: 1px solid var(--line);
}

.action-bar .action-spacer {
    flex: 1;
}

.keyboard-hint {
    color: var(--subtle);
    font-size: 0.65rem;
}

.runner-pane {
    min-height: 260px;
}

.runner-frame {
    width: 100%;
    min-height: 220px;
    background: #fff;
    border: 0;
}

.empty-state {
    display: grid;
    min-height: 190px;
    padding: 1.5rem;
    place-items: center;
    color: var(--muted);
    text-align: center;
}

.empty-state p {
    max-width: 320px;
    margin: 0;
    font-size: 0.8rem;
    line-height: 1.55;
}

.result-summary {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    gap: 0.85rem;
    align-items: center;
    padding: 1rem;
    border-bottom: 1px solid var(--line);
}

.score-ring {
    display: grid;
    width: 4rem;
    height: 4rem;
    place-items: center;
    color: var(--accent);
    background: var(--panel-raised);
    border: 3px solid var(--accent);
    border-radius: 50%;
    font: 800 0.9rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.result-summary h3 {
    margin: 0 0 0.3rem;
    font-size: 0.92rem;
}

.result-summary p {
    margin: 0;
    color: var(--muted);
    font-size: 0.72rem;
}

.result-list {
    display: grid;
    gap: 0.55rem;
    margin: 0;
    padding: 0.8rem;
    list-style: none;
}

.result-item {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 0.65rem;
    align-items: start;
    padding: 0.7rem;
    background: var(--panel-raised);
    border: 1px solid var(--line);
    border-radius: 0.48rem;
}

.result-icon {
    display: grid;
    width: 1.35rem;
    height: 1.35rem;
    place-items: center;
    border-radius: 50%;
    font-size: 0.7rem;
    font-weight: 800;
}

.result-passed .result-icon {
    color: #061610;
    background: var(--success);
}

.result-failed .result-icon,
.result-error .result-icon {
    color: #26050b;
    background: var(--danger);
}

.result-item strong,
.result-item small {
    display: block;
}

.result-item strong {
    font-size: 0.75rem;
}

.result-item small {
    margin-top: 0.25rem;
    color: var(--muted);
    font-size: 0.68rem;
    line-height: 1.4;
}

.result-weight {
    color: var(--subtle);
    font: 700 0.65rem/1.3 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.console-output {
    margin: 0 0.8rem 0.8rem;
    overflow: hidden;
    background: #08101d;
    border: 1px solid var(--line);
    border-radius: 0.48rem;
}

.console-output-heading {
    display: flex;
    gap: 0.75rem;
    align-items: center;
    justify-content: space-between;
    padding: 0.65rem 0.75rem;
}

.console-output-heading h3 {
    margin: 0;
    font-size: 0.75rem;
}

.console-output-heading span,
.console-output-empty,
.console-output-truncated {
    color: var(--muted);
    font-size: 0.68rem;
}

.console-output-list {
    max-height: 14rem;
    margin: 0;
    padding: 0;
    overflow: auto;
    border-top: 1px solid var(--line);
    list-style: none;
}

.console-output-list:focus-visible {
    outline-offset: -3px;
}

.console-output-entry {
    display: grid;
    grid-template-columns: 3.4rem minmax(0, 1fr);
    gap: 0.65rem;
    padding: 0.55rem 0.7rem;
    border-bottom: 1px solid var(--line);
}

.console-output-entry:last-child {
    border-bottom: 0;
}

.console-output-level {
    color: var(--subtle);
    font: 700 0.62rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
    text-transform: uppercase;
}

.console-output-entry.console-info .console-output-level {
    color: var(--accent);
}

.console-output-entry.console-warn .console-output-level {
    color: var(--amber);
}

.console-output-entry.console-error .console-output-level {
    color: var(--danger);
}

.console-output-content {
    min-width: 0;
}

.console-output-message {
    min-width: 0;
    margin: 0;
    overflow-wrap: anywhere;
    color: #dce7ff;
    font: 0.7rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
    white-space: pre-wrap;
}

.console-output-context {
    display: block;
    margin-top: 0.2rem;
    color: var(--subtle);
    font: 0.6rem/1.4 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.console-output-empty,
.console-output-truncated {
    margin: 0;
    padding: 0 0.75rem 0.7rem;
}

.diagnostic-list {
    display: grid;
    gap: 0.45rem;
    margin: 0;
    padding: 0.8rem;
    list-style: none;
}

.diagnostic-list li {
    padding: 0.65rem;
    color: var(--muted);
    background: rgba(255, 142, 156, 0.07);
    border-left: 3px solid var(--danger);
    font: 0.7rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.diff-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.65rem;
}

.diff-column {
    min-width: 0;
}

.diff-column h3 {
    color: var(--muted);
    font-size: 0.72rem;
}

.diff-column pre {
    max-height: 430px;
    margin: 0;
    padding: 0.8rem;
    overflow: auto;
    color: var(--muted);
    background: #08101d;
    border: 1px solid var(--line);
    border-radius: 0.45rem;
    font: 0.68rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
    white-space: pre;
}

.checkpoint-list,
.hint-list {
    display: grid;
    gap: 0.55rem;
    margin: 0;
    padding: 0;
    list-style: none;
}

.checkpoint-list li,
.hint-list li {
    padding: 0.7rem;
    background: var(--panel-raised);
    border: 1px solid var(--line);
    border-radius: 0.45rem;
}

.checkpoint-list button,
.hint-list button {
    width: 100%;
    margin-top: 0.5rem;
}

.checkpoint-list strong,
.checkpoint-list small {
    display: block;
}

.checkpoint-list small {
    margin-top: 0.2rem;
    color: var(--subtle);
    font-size: 0.65rem;
}

.workspace-error,
.not-found-page {
    width: min(720px, calc(100% - 3rem));
    margin: 6rem auto;
    padding: 2rem;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 0.8rem;
}

.workspace-error p,
.not-found-page p {
    color: var(--muted);
}

@media (max-width: 1120px) {
    .workspace-grid {
        grid-template-columns: minmax(230px, 0.7fr) minmax(420px, 1.5fr);
    }

    .runner-panel {
        grid-column: 1 / -1;
    }

    .runner-panel .panel-scroll {
        max-height: none;
    }
}

@media (max-width: 900px) {
    .catalog-hero,
    .runtime-section {
        grid-template-columns: 1fr;
    }

    .catalog-hero {
        min-height: auto;
    }

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

    .principles-grid article:nth-child(2) {
        border-right: 0;
    }

    .principles-grid article:nth-child(-n + 2) {
        border-bottom: 1px solid var(--line);
    }

    .workspace-grid {
        grid-template-columns: 1fr;
    }

    .runner-panel {
        grid-column: auto;
    }

    .panel-scroll {
        max-height: none;
    }
}

@media (max-width: 700px) {
    .site-header {
        flex-wrap: wrap;
        gap: 0.7rem;
        width: min(100% - 2rem, 1440px);
        padding: 0.8rem 0;
    }

    .site-nav {
        order: 3;
        width: 100%;
    }

    .site-nav a {
        flex: 1;
        text-align: center;
    }

    .page-shell,
    .narrow-shell {
        width: min(100% - 2rem, 1240px);
    }

    .catalog-hero {
        padding: 3.5rem 0;
    }

    .principles-grid,
    .runtime-grid,
    .choice-grid,
    .comparison-grid,
    .settings-grid,
    .diff-grid {
        grid-template-columns: 1fr;
    }

    .principles-grid article,
    .runtime-grid article {
        border-right: 0;
        border-bottom: 1px solid var(--line);
    }

    .principles-grid article:last-child,
    .runtime-grid article:last-child {
        border-bottom: 0;
    }

    .challenge-card {
        grid-template-columns: auto minmax(0, 1fr);
    }

    .challenge-action {
        grid-column: 2;
        justify-items: start;
    }

    .challenge-action p {
        text-align: left;
    }

    .section-heading,
    .preflight-finish,
    .workspace-header {
        align-items: stretch;
        flex-direction: column;
    }

    .workspace-header-meta {
        justify-content: flex-start;
    }

    .tutorial-section {
        grid-template-columns: 1fr;
    }

    .assessment-editor,
    .assessment-editor .cm-editor,
    .assessment-editor .cm-scroller {
        min-height: 430px;
    }

    .keyboard-hint {
        display: none;
    }
}

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

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