/* ============================================================================
   Soroban Testkit — custom mdBook theme
   Layer 1: design tokens         Layer 4: content components
   Layer 2: theme palettes        Layer 5: utilities used from Markdown
   Layer 3: chrome (sidebar, bar)
   Paths in book.toml: additional-css = ["theme/custom.css"]
   ========================================================================== */

/* ----------------------------------------------------------------------------
   1. Design tokens
   -------------------------------------------------------------------------- */
:root {
    /* Layout */
    --content-max-width: 1080px;
    --page-padding: 24px;
    --menu-bar-height: 56px;
    --sidebar-target-width: 320px;
    --code-font-size: 0.86em;

    /* Type */
    --tk-font-sans: "Inter", "Segoe UI", -apple-system, BlinkMacSystemFont,
        "Helvetica Neue", Arial, sans-serif;
    --tk-font-display: "Inter", "Segoe UI", -apple-system, BlinkMacSystemFont,
        sans-serif;
    --tk-font-mono: "JetBrains Mono", var(--mono-font);

    /* Brand */
    --tk-brand: #3b6ef6;
    --tk-brand-deep: #16225c;
    --tk-accent: #17e0a6;
    --tk-accent-dim: #0f9c76;
    --tk-warn: #e8a33d;

    /* Shape */
    --tk-radius-sm: 6px;
    --tk-radius: 12px;
    --tk-radius-lg: 18px;
    --tk-border-width: 1px;
    --tk-shadow-sm: 0 1px 2px rgba(12, 18, 40, 0.08);
    --tk-shadow: 0 6px 20px rgba(12, 18, 40, 0.12);
    --tk-gap: 16px;

    /* Neutral surfaces (theme blocks below refine per palette) */
    --tk-surface: #ffffff;
    --tk-surface-alt: #f5f7fd;
    --tk-surface-border: #e2e6f3;
    --tk-muted: #5b6583;

    /* Chrome: the sidebar keeps one dark identity across every palette */
    --sidebar-bg: #0d1428;
    --sidebar-fg: #b9c4e0;
    --sidebar-non-existant: #55618a;
    --sidebar-active: var(--tk-accent);
    --sidebar-spacer: #1d2749;
    --sidebar-header-border-color: #24304f;
    --icons: #8592b6;
    --icons-hover: #ffffff;
    --scrollbar: #34406a;
    --searchbar-bg: #16203c;
    --searchbar-border-color: #2a3760;
    --searchbar-fg: #e6ebfa;
    --searchbar-shadow-color: rgba(0, 0, 0, 0.35);
    --searchresults-header-fg: #8592b6;
    --searchresults-border-color: #2a3760;
    --searchresults-li-bg: #16203c;
    --search-mark-bg: var(--tk-accent);
    --overlay-bg: rgba(6, 10, 24, 0.55);
}

/* ----------------------------------------------------------------------------
   2. Theme palettes — content surface only, chrome stays branded
   -------------------------------------------------------------------------- */
.light,
html:not(.js) {
    --bg: #fdfdfe;
    --fg: #1b2340;
    --links: var(--tk-brand);
    --inline-code-color: #b4345f;
    --quote-bg: #f3f6fd;
    --quote-border: var(--tk-brand);
    --table-border-color: #e2e6f3;
    --table-header-bg: #eef2fb;
    --table-alternate-bg: #f7f9fd;
    --theme-popup-bg: #ffffff;
    --theme-popup-border: #dfe4f2;
    --theme-hover: #f1f5fd;
    --copy-button-filter: invert(60%) sepia(12%) saturate(500%)
        hue-rotate(180deg);
    --color-scheme: light;
    --tk-surface: #ffffff;
    --tk-surface-alt: #f5f7fd;
    --tk-surface-border: #e2e6f3;
    --tk-muted: #5b6583;
    --tk-code-bg: #f7f8fc;
}

.coal,
.navy,
.ayu {
    --bg: #111a30;
    --fg: #dde4f5;
    --links: #86a9ff;
    --inline-code-color: #7fe9c8;
    --quote-bg: #182543;
    --quote-border: var(--tk-brand);
    --table-border-color: #26325a;
    --table-header-bg: #1a2545;
    --table-alternate-bg: #16203b;
    --theme-popup-bg: #16203b;
    --theme-popup-border: #2a3760;
    --theme-hover: #1f2c52;
    --color-scheme: dark;
    --tk-surface: #17223e;
    --tk-surface-alt: #1d2a4d;
    --tk-surface-border: #2a3760;
    --tk-muted: #93a0c4;
    --tk-code-bg: #0f1830;
}

.coal,
.navy,
.ayu {
    --tk-shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --tk-shadow: 0 8px 24px rgba(0, 0, 0, 0.45);
}

/* ----------------------------------------------------------------------------
   3. Base typography
   -------------------------------------------------------------------------- */
html {
    font-family: var(--tk-font-sans);
    -webkit-font-smoothing: antialiased;
}

.content {
    line-height: 1.75;
    letter-spacing: 0.005em;
}

.content main {
    padding-top: 8px;
}

.content h1 {
    font-family: var(--tk-font-display);
    font-size: 2.1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    margin: 0 0 0.6em;
    padding-bottom: 0.35em;
    border-bottom: var(--tk-border-width) solid var(--tk-surface-border);
}

.content h2 {
    font-size: 1.45rem;
    font-weight: 650;
    letter-spacing: -0.01em;
    margin-top: 2.4em;
}

.content h3 {
    font-size: 1.15rem;
    font-weight: 600;
    margin-top: 2em;
}

.content h2,
.content h3 {
    scroll-margin-top: calc(var(--menu-bar-height) + 12px);
}

.content h2::before,
.content h3::before {
    content: "";
    display: block;
    width: 34px;
    height: 3px;
    border-radius: 3px;
    margin-bottom: 0.45em;
    background: linear-gradient(90deg, var(--tk-brand), var(--tk-accent));
}

.content p,
.content li {
    color: var(--fg);
}

.content strong {
    font-weight: 650;
}

/* Sidebar chapter labels read as section eyebrows */
.chapter li.part-title {
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--sidebar-non-existant);
    margin-top: 1.6em;
}

/* ----------------------------------------------------------------------------
   4. Chrome: menu bar, sidebar, page furniture
   -------------------------------------------------------------------------- */
#mdbook-menu-bar,
.menu-bar {
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    backdrop-filter: blur(10px);
    border-bottom: var(--tk-border-width) solid var(--tk-surface-border);
    box-shadow: none;
}

.menu-title,
#mdbook-menu-bar .icon-button {
    color: var(--fg);
}

.sidebar .sidebar-scrollbox {
    padding: 14px 16px 40px;
}

.sidebar .chapter {
    padding: 0 4px;
}

.sidebar .chapter li {
    margin: 1px 0;
}

/* mdBook 0.5 nests each entry as li > span.chapter-link-wrapper > a */
.sidebar .chapter .chapter-link-wrapper > a {
    display: block;
    padding: 7px 12px;
    border-radius: var(--tk-radius-sm);
    color: var(--sidebar-fg);
    font-size: 0.9rem;
    text-decoration: none;
    transition: background-color 140ms ease, color 140ms ease;
}

.sidebar .chapter .chapter-link-wrapper > a:hover {
    background: rgba(255, 255, 255, 0.06);
    color: #ffffff;
    text-decoration: none;
}

.sidebar .chapter .chapter-link-wrapper > a.active {
    background: linear-gradient(
        90deg,
        rgba(59, 110, 246, 0.28),
        rgba(23, 224, 166, 0.12)
    );
    color: #ffffff;
    font-weight: 600;
    box-shadow: inset 2px 0 0 var(--tk-accent);
}

/* top-level chapters carry a touch more weight than sub-sections */
.sidebar .chapter > li > .chapter-link-wrapper > a {
    font-weight: 600;
    color: #dfe6fa;
}

/* the "on this page" tree under the active chapter */
.sidebar .on-this-page {
    margin: 2px 0 6px 10px;
    padding-left: 10px;
    border-left: 1px solid #2a3760;
}

.sidebar .on-this-page .chapter-link-wrapper > a {
    font-size: 0.82rem;
    padding: 4px 10px;
    color: var(--sidebar-non-existant);
}

.sidebar .on-this-page .chapter-link-wrapper > a:hover,
.sidebar .on-this-page .chapter-link-wrapper > a.active {
    color: #ffffff;
}

.sidebar .header-item {
    list-style: none;
}

/* Prev / next page cards */
.nav-chapters {
    background: var(--tk-surface);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-radius: var(--tk-radius);
    box-shadow: var(--tk-shadow-sm);
    min-height: 96px;
    max-width: 46%;
    padding: 0 22px;
    transition: transform 140ms ease, box-shadow 140ms ease;
}

.nav-chapters:hover {
    transform: translateY(-2px);
    box-shadow: var(--tk-shadow);
    background: var(--tk-surface);
}

.nav-links {
    font-size: 1.02rem;
    font-weight: 600;
    color: var(--fg);
}

.sidebar-resize-indicator,
.sidebar-resize-handle {
    background: transparent;
}

/* ----------------------------------------------------------------------------
   5. Code blocks
   -------------------------------------------------------------------------- */
.content pre {
    background: var(--tk-code-bg);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-left: 3px solid var(--tk-brand);
    border-radius: var(--tk-radius);
    padding: 16px 18px;
    box-shadow: var(--tk-shadow-sm);
    overflow-x: auto;
}

.content pre code {
    font-family: var(--tk-font-mono);
    line-height: 1.65;
}

:not(pre) > code,
.hljs {
    font-family: var(--tk-font-mono);
}

:not(pre) > code {
    background: var(--tk-surface-alt);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-radius: var(--tk-radius-sm);
    padding: 0.12em 0.42em;
}

/* keep highlighted tokens readable against our surfaces */
.hljs-string,
.hljs-attr {
    color: var(--tk-accent-dim);
}

/* ----------------------------------------------------------------------------
   6. Tables, callouts, blockquotes
   -------------------------------------------------------------------------- */
.table-wrapper {
    border-radius: var(--tk-radius);
    box-shadow: var(--tk-shadow-sm);
    margin: 1.6em 0;
}

table {
    border-collapse: separate;
    border-spacing: 0;
    font-size: 0.94em;
    width: 100%;
}

table thead th {
    background: var(--tk-brand-deep);
    color: #eaf0ff;
    font-family: var(--tk-font-sans);
    font-size: 0.82em;
    font-weight: 650;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    padding: 12px 16px;
    border: none;
}

table thead th:first-child {
    border-top-left-radius: var(--tk-radius);
}

table thead th:last-child {
    border-top-right-radius: var(--tk-radius);
}

table tbody td {
    padding: 11px 16px;
    border-bottom: var(--tk-border-width) solid var(--table-border-color);
}

blockquote {
    background: var(--quote-bg);
    border-left: 4px solid var(--quote-border);
    border-radius: 0 var(--tk-radius) var(--tk-radius) 0;
    margin: 1.6em 0;
    padding: 14px 20px;
}

/* ----------------------------------------------------------------------------
   7. Components used from Markdown (raw HTML blocks)
   -------------------------------------------------------------------------- */
.tk-hero {
    position: relative;
    overflow: hidden;
    background: radial-gradient(
            120% 160% at 12% 0%,
            rgba(59, 110, 246, 0.85) 0%,
            rgba(22, 34, 92, 0.95) 45%,
            rgba(9, 14, 38, 1) 100%
        ),
        var(--tk-brand-deep);
    border-radius: var(--tk-radius-lg);
    color: #eef3ff;
    padding: 40px 36px 34px;
    margin: 6px 0 30px;
    box-shadow: var(--tk-shadow);
}

.tk-hero::after {
    content: "";
    position: absolute;
    right: -60px;
    top: -70px;
    width: 260px;
    height: 260px;
    border-radius: 50%;
    background: radial-gradient(
        circle,
        rgba(23, 224, 166, 0.32),
        rgba(23, 224, 166, 0)
    );
    pointer-events: none;
}

.tk-hero__eyebrow {
    font-size: 0.74rem;
    font-weight: 700;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--tk-accent);
    margin: 0 0 10px;
}

.tk-hero a {
    color: var(--tk-accent);
    text-decoration: none;
}

.tk-hero a:hover {
    text-decoration: underline;
}

.tk-hero .tk-hero__title {
    font-family: var(--tk-font-display);
    font-size: 2.35rem;
    font-weight: 750;
    letter-spacing: -0.025em;
    line-height: 1.15;
    margin: 0 0 12px;
    border: none;
    padding: 0;
    color: #ffffff;
}

.tk-hero__lede {
    max-width: 62ch;
    font-size: 1.03rem;
    line-height: 1.7;
    color: #c6d3f2;
    margin: 0 0 22px;
}

.tk-hero__actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.tk-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    border-radius: 999px;
    font-size: 0.9rem;
    font-weight: 600;
    text-decoration: none;
    transition: transform 120ms ease, box-shadow 120ms ease,
        background-color 120ms ease;
}

.tk-btn:hover {
    transform: translateY(-1px);
    text-decoration: none;
}

.tk-btn--primary {
    background: var(--tk-accent);
    color: #062033;
    box-shadow: 0 4px 14px rgba(23, 224, 166, 0.3);
}

.tk-btn--ghost {
    background: rgba(255, 255, 255, 0.1);
    color: #eef3ff;
    box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.24);
}

/* Badge strip ------------------------------------------------------------- */
.tk-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 18px 0 0;
}

.tk-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 12px;
    border-radius: 999px;
    background: var(--tk-surface-alt);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    color: var(--tk-muted);
    font-size: 0.76rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    text-decoration: none;
}

.tk-badge--brand {
    background: rgba(59, 110, 246, 0.12);
    border-color: rgba(59, 110, 246, 0.34);
    color: var(--links);
}

.tk-badge--accent {
    background: rgba(23, 224, 166, 0.14);
    border-color: rgba(15, 156, 118, 0.4);
    color: var(--tk-accent-dim);
}

/* Chips that sit on the dark hero read as glass, not paper */
.tk-hero .tk-badge {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.22);
    color: #dbe6ff;
}

.tk-hero .tk-badge--brand {
    background: rgba(255, 255, 255, 0.16);
    color: #ffffff;
}

.tk-hero .tk-badge--accent {
    background: rgba(23, 224, 166, 0.2);
    border-color: rgba(23, 224, 166, 0.45);
    color: #9df3d8;
}

/* Card grids -------------------------------------------------------------- */
.tk-grid {
    display: grid;
    gap: var(--tk-gap);
    margin: 1.4em 0 2em;
}

.tk-grid--2 {
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.tk-grid--4 {
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.tk-grid--3 {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.tk-card {
    background: var(--tk-surface);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-radius: var(--tk-radius);
    box-shadow: var(--tk-shadow-sm);
    padding: 20px 20px 18px;
    transition: transform 140ms ease, box-shadow 140ms ease,
        border-color 140ms ease;
}

.tk-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--tk-shadow);
    border-color: rgba(59, 110, 246, 0.4);
}

.tk-card__kicker {
    display: inline-block;
    font-family: var(--tk-font-mono);
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.01em;
    color: var(--links);
    margin: 0 0 6px;
}

.tk-card h3,
.tk-card__title {
    font-size: 1.03rem;
    font-weight: 650;
    margin: 0 0 8px;
    padding: 0;
    border: none;
    color: var(--fg);
}

.tk-card h3::before,
.tk-card__title::before {
    content: none;
}

.tk-card p,
.tk-card__body {
    font-size: 0.9rem;
    line-height: 1.65;
    color: var(--tk-muted);
    margin: 0;
}

.tk-card__meta {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-top: 14px;
}

.tk-card--accent {
    border-left: 3px solid var(--tk-accent);
}

/* Problem / solution rows ------------------------------------------------- */
.tk-problems {
    display: grid;
    gap: 10px;
    margin: 1.2em 0 1.8em;
}

.tk-problem {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2px;
    background: var(--tk-surface-alt);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-radius: var(--tk-radius-sm);
    padding: 14px 18px;
}

.tk-problem__label {
    font-size: 0.74rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--tk-warn);
}

.tk-problem__body {
    font-size: 0.94rem;
    color: var(--fg);
}

.tk-problem__fix {
    font-size: 0.9rem;
    color: var(--tk-muted);
}

.tk-problem__fix b {
    color: var(--tk-accent-dim);
}

/* Numbered steps ---------------------------------------------------------- */
.tk-steps {
    list-style: none;
    counter-reset: tk-step;
    margin: 1.4em 0 2em;
    padding: 0;
}

.tk-steps > li {
    counter-increment: tk-step;
    position: relative;
    margin: 0 0 18px;
    padding: 4px 0 0 54px;
    min-height: 34px;
}

.tk-steps > li::before {
    content: counter(tk-step);
    position: absolute;
    left: 0;
    top: 0;
    display: grid;
    place-items: center;
    width: 34px;
    height: 34px;
    border-radius: 50%;
    background: var(--tk-brand-deep);
    color: #ffffff;
    font-family: var(--tk-font-mono);
    font-size: 0.86rem;
    font-weight: 700;
}

.tk-steps > li::after {
    content: "";
    position: absolute;
    left: 16px;
    top: 40px;
    bottom: -18px;
    width: 2px;
    background: var(--tk-surface-border);
}

.tk-steps > li:last-child::after {
    content: none;
}

.tk-steps h4 {
    font-size: 0.98rem;
    font-weight: 650;
    margin: 4px 0 6px;
}

/* Callouts ---------------------------------------------------------------- */
.tk-callout {
    display: block;
    border-radius: var(--tk-radius);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-left: 4px solid var(--tk-brand);
    background: var(--tk-surface-alt);
    padding: 14px 18px;
    margin: 1.5em 0;
    font-size: 0.93rem;
}

.tk-callout__title {
    display: block;
    font-size: 0.74rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--tk-brand);
    margin-bottom: 4px;
}

.tk-callout p:last-child {
    margin-bottom: 0;
}

.tk-callout--tip {
    border-left-color: var(--tk-accent);
}

.tk-callout--tip .tk-callout__title {
    color: var(--tk-accent-dim);
}

.tk-callout--warn {
    border-left-color: var(--tk-warn);
}

.tk-callout--warn .tk-callout__title {
    color: var(--tk-warn);
}

/* Spec table (crate pages) ------------------------------------------------ */
.tk-spec {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
    gap: 10px;
    margin: 1.2em 0 1.8em;
}

.tk-spec__item {
    background: var(--tk-surface);
    border: var(--tk-border-width) solid var(--tk-surface-border);
    border-radius: var(--tk-radius-sm);
    padding: 12px 14px;
}

.tk-spec__key {
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--tk-muted);
}

.tk-spec__value {
    font-family: var(--tk-font-mono);
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--fg);
}

/* Small helpers ----------------------------------------------------------- */
.tk-muted {
    color: var(--tk-muted);
}

.tk-eyebrow {
    font-size: 0.74rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--tk-brand);
}

.tk-divider {
    border: none;
    border-top: var(--tk-border-width) solid var(--tk-surface-border);
    margin: 2.2em 0;
}

.tk-cta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    background: linear-gradient(
        100deg,
        rgba(59, 110, 246, 0.14),
        rgba(23, 224, 166, 0.12)
    );
    border: var(--tk-border-width) solid rgba(59, 110, 246, 0.3);
    border-radius: var(--tk-radius);
    padding: 20px 24px;
    margin: 2em 0 1em;
}

.tk-cta p {
    margin: 0;
    font-size: 0.95rem;
    color: var(--fg);
}

/* ----------------------------------------------------------------------------
   8. Responsive + print
   -------------------------------------------------------------------------- */
@media (max-width: 711px) {
    :root {
        --page-padding: 14px;
    }

    .tk-hero {
        padding: 26px 20px 24px;
        border-radius: var(--tk-radius);
    }

    .tk-hero__title {
        font-size: 1.75rem;
    }

    .tk-grid--2,
    .tk-grid--3,
    .tk-grid--4 {
        grid-template-columns: 1fr;
    }

    .content h1 {
        font-size: 1.7rem;
    }
}

@media print {
    .tk-hero,
    .tk-card {
        box-shadow: none;
    }
}