:root {
    --bg: #000000;
    --bg-soft: #0b0d11;
    --code-bg: #0f1115;
    --text: #f3f4f6;
    --muted: #9ca3af;
    --accent: #7dd3fc;
    --accent-strong: #38bdf8;
    --border: #1f2937;
    --border-soft: rgba(125, 211, 252, 0.14);
    --maxw: min(1680px, 94vw);
    --header-h: 60px;
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    background: var(--bg);
    color: var(--text);
    font-family: "Inter", "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); }

code, pre, kbd {
    font-family: "JetBrains Mono", "Fira Code", Menlo, Consolas, monospace;
}

/* Operators such as the forward pipe `|>` must read as two separate
   glyphs. JetBrains Mono / Fira Code ligate `|>` into a single arrow,
   which is ambiguous in code. Disable ligatures on every code surface,
   including the embedded CodeMirror editor. */
code,
pre,
kbd,
.cm-editor,
.cm-content,
.cm-line {
    font-variant-ligatures: none;
    font-feature-settings: "liga" 0, "calt" 0;
}

/* ------------------------------------------------------------------ *
 * Header
 * ------------------------------------------------------------------ */
.tour-header {
    position: sticky;
    top: 0;
    z-index: 20;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    height: var(--header-h);
    padding: 0 1.25rem;
    background: rgba(0, 0, 0, 0.82);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border);
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 0.55rem;
    text-decoration: none;
    color: var(--text);
}
.brand-logo { width: 30px; height: auto; }
.brand-name {
    font-weight: 800;
    font-size: 1.2rem;
    letter-spacing: -0.02em;
}
.brand-sub {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--accent-strong);
    border: 1px solid var(--border-soft);
    border-radius: 999px;
    padding: 0.1rem 0.55rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.tour-topnav {
    display: flex;
    gap: 0.4rem 1.4rem;
    flex-wrap: wrap;
}
.tour-topnav a {
    color: var(--muted);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
}
.tour-topnav a:hover { color: var(--accent-strong); }

.tour-noscript,
.tour-fatal {
    max-width: 640px;
    margin: 3rem auto;
    padding: 0 1.25rem;
    color: var(--muted);
}

/* ------------------------------------------------------------------ *
 * Layout: step list | (prose + playground)
 * ------------------------------------------------------------------ */
.tour-layout {
    max-width: var(--maxw);
    margin: 0 auto;
    padding: 1.5rem 1.25rem 4rem;
    display: grid;
    grid-template-columns: 232px minmax(0, 1fr);
    gap: 1.75rem;
    align-items: start;
}

/* Sidebar step list */
.tour-sidebar {
    position: sticky;
    top: calc(var(--header-h) + 1.25rem);
    align-self: start;
}
.tour-sidebar h2 {
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--muted);
    font-weight: 700;
    margin: 0 0 0.7rem 0.2rem;
}
.tour-steps {
    list-style: none;
    margin: 0;
    padding: 0;
    counter-reset: step;
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
}
.tour-steps li { margin: 0; }
.step-btn {
    counter-increment: step;
    display: flex;
    align-items: baseline;
    gap: 0.6rem;
    width: 100%;
    text-align: left;
    cursor: pointer;
    font-family: inherit;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--muted);
    background: transparent;
    border: 1px solid transparent;
    border-radius: 8px;
    padding: 0.5rem 0.7rem;
    transition: color 120ms ease, background 120ms ease, border-color 120ms ease;
}
.step-btn::before {
    content: counter(step);
    flex: 0 0 1.4em;
    text-align: center;
    font-family: "JetBrains Mono", monospace;
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--muted);
    background: var(--bg-soft);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 0.05rem 0;
}
.step-btn:hover {
    color: var(--text);
    background: rgba(125, 211, 252, 0.06);
}
.step-btn[aria-current="step"] {
    color: var(--text);
    background: rgba(56, 189, 248, 0.10);
    border-color: var(--border-soft);
}
.step-btn[aria-current="step"]::before {
    color: #04121b;
    background: var(--accent-strong);
    border-color: var(--accent-strong);
}
.step-btn:focus-visible {
    outline: 2px solid var(--accent-strong);
    outline-offset: 2px;
}

/* Main content */
.tour-content { min-width: 0; }

.tour-progress {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
    color: var(--muted);
    font-size: 0.85rem;
    font-family: "JetBrains Mono", monospace;
}
.tour-progress .bar {
    flex: 1;
    height: 4px;
    border-radius: 999px;
    background: var(--border);
    overflow: hidden;
}
.tour-progress .bar i {
    display: block;
    height: 100%;
    background: var(--accent-strong);
    border-radius: 999px;
    transition: width 220ms ease;
}

.tour-split {
    display: grid;
    /* Favor the code editor: prose stays readable, the playground gets
       the bulk of the (now wider) row. */
    grid-template-columns: minmax(0, 2fr) minmax(0, 3.4fr);
    gap: 1.5rem;
    align-items: start;
}

.tour-prose h1 {
    font-size: 1.7rem;
    font-weight: 750;
    letter-spacing: -0.02em;
    margin: 0.2rem 0 1rem;
}
.tour-prose p {
    color: #d6dae2;
    margin: 0 0 1rem;
}
.tour-prose p:last-child { margin-bottom: 0; }
.tour-prose code {
    font-size: 0.86em;
    background: rgba(125, 211, 252, 0.10);
    color: var(--accent);
    padding: 0.1em 0.35em;
    border-radius: 5px;
}
.tour-prose ul {
    margin: 0 0 1rem;
    padding-left: 1.2rem;
    color: #d6dae2;
}
.tour-prose li { margin: 0.2rem 0; }
.tour-prose strong { color: var(--text); font-weight: 650; }

/* Playground host */
.tour-play {
    min-height: 320px;
    border: 1px solid var(--border);
    border-radius: 12px;
    background: var(--code-bg);
    overflow: hidden;
}
.tour-play-loading,
.tour-play-fallback {
    padding: 1.1rem 1.2rem;
    color: var(--muted);
    font-size: 0.92rem;
}
.tour-play-fallback pre {
    margin: 0 0 0.8rem;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1rem 1.1rem;
    overflow-x: auto;
    color: var(--text);
    font-size: 0.86rem;
    line-height: 1.55;
    white-space: pre;
}
.tour-play-fallback .note { margin: 0; }
.tour-play-loading {
    display: flex;
    align-items: center;
    gap: 0.6rem;
}
.tour-play-loading .spin {
    width: 14px;
    height: 14px;
    border: 2px solid var(--border);
    border-top-color: var(--accent-strong);
    border-radius: 50%;
    animation: tour-spin 0.8s linear infinite;
}
@keyframes tour-spin { to { transform: rotate(360deg); } }

/* Controls */
.tour-controls {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-top: 1.75rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border);
}
.nav-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.45em;
    cursor: pointer;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.98rem;
    padding: 0.6rem 1.3rem;
    border-radius: 999px;
    border: 1px solid var(--border-soft);
    background: transparent;
    color: var(--accent);
    transition: background 120ms ease, color 120ms ease, border-color 120ms ease, transform 120ms ease;
}
.nav-btn:hover:not([disabled]) {
    background: rgba(125, 211, 252, 0.10);
    color: var(--accent-strong);
    border-color: var(--accent-strong);
    transform: translateY(-1px);
}
.nav-btn.primary {
    background: var(--accent-strong);
    border-color: var(--accent-strong);
    color: #04121b;
}
.nav-btn.primary:hover:not([disabled]) {
    background: var(--accent);
    border-color: var(--accent);
    color: #04121b;
}
.nav-btn[disabled] {
    opacity: 0.35;
    cursor: not-allowed;
}
.nav-btn:focus-visible {
    outline: 2px solid var(--accent-strong);
    outline-offset: 2px;
}
.tour-controls .center {
    color: var(--muted);
    font-size: 0.85rem;
    font-family: "JetBrains Mono", monospace;
}

/* ------------------------------------------------------------------ *
 * Responsive
 * ------------------------------------------------------------------ */
@media (max-width: 960px) {
    .tour-layout {
        grid-template-columns: 1fr;
        gap: 1.25rem;
    }
    .tour-sidebar {
        position: static;
        top: auto;
    }
    .tour-steps {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 0.4rem;
    }
    .step-btn { width: auto; }
    .tour-split {
        grid-template-columns: 1fr;
        gap: 1.25rem;
    }
}

@media (max-width: 600px) {
    .tour-header { padding: 0 0.9rem; }
    .brand-sub { display: none; }
    .tour-prose h1 { font-size: 1.4rem; }
    .nav-btn { padding: 0.55rem 1rem; font-size: 0.92rem; }
    .tour-controls .center { display: none; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { transition: none !important; animation: none !important; }
}