/* GadNest design system
   Technical-manual look: drafting-paper background, graphite ink, one teal accent,
   monospace figure labels, diagrams as the protagonist.
   RULE: a colour used as a BACKGROUND never doubles as a TEXT colour. Every filled surface
   (buttons, footer, tooltip, toggled chips) has its own background + foreground token,
   defined for both light and dark mode. */

@font-face { font-family: "IBM Plex Sans"; font-weight: 400; font-style: normal; font-display: swap;
  src: url("/assets/fonts/ibm-plex-sans-400.woff2") format("woff2"); }
@font-face { font-family: "IBM Plex Sans"; font-weight: 600; font-style: normal; font-display: swap;
  src: url("/assets/fonts/ibm-plex-sans-600.woff2") format("woff2"); }
@font-face { font-family: "IBM Plex Sans Condensed"; font-weight: 600; font-style: normal; font-display: swap;
  src: url("/assets/fonts/ibm-plex-sans-condensed-600.woff2") format("woff2"); }
@font-face { font-family: "IBM Plex Sans Condensed"; font-weight: 700; font-style: normal; font-display: swap;
  src: url("/assets/fonts/ibm-plex-sans-condensed-700.woff2") format("woff2"); }
@font-face { font-family: "IBM Plex Mono"; font-weight: 400; font-style: normal; font-display: swap;
  src: url("/assets/fonts/ibm-plex-mono-400.woff2") format("woff2"); }
@font-face { font-family: "IBM Plex Mono"; font-weight: 500; font-style: normal; font-display: swap;
  src: url("/assets/fonts/ibm-plex-mono-500.woff2") format("woff2"); }

:root {
  color-scheme: light dark;

  /* surfaces */
  --bg: #f4f3ee;
  --bg-raised: #ffffff;
  --bg-band: #eceae2;
  --line: #d9d6cb;
  --line-strong: #b7b3a5;
  --grid: rgba(27, 31, 35, 0.07);

  /* text */
  --ink: #1b1f23;
  --ink-soft: #4a525a;

  /* the single accent */
  --accent: #0b7e84;          /* fills, borders, ticks */
  --accent-ink: #075a5e;      /* teal used AS TEXT on --bg / --bg-raised */
  --accent-soft: #dcefee;     /* tinted panel behind teal text */

  /* filled controls: background + its own foreground */
  --btn-bg: #075a5e;
  --btn-fg: #ffffff;
  --btn-bg-hover: #04464a;
  --on-accent: #ffffff;       /* text/shapes drawn on top of --accent-ink fills */
  --ghost-fg: #075a5e;
  --ghost-border: #075a5e;
  --ghost-hover-bg: #dcefee;

  /* footer and tooltip surfaces */
  --footer-bg: #1b1f23;
  --footer-fg: #e8ecee;
  --footer-muted: #a3afb5;
  --footer-link: #c4ecec;
  --footer-line: #353d43;
  --tip-bg: #1b1f23;
  --tip-fg: #f4f6f7;

  /* notices */
  --warn-bg: #fbf1dc;
  --warn-ink: #5e4204;
  --warn-line: #e1c98e;
  --error-ink: #a52a1d;
  --ok-ink: #17623a;

  --radius: 10px;
  --radius-sm: 6px;
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Arial, sans-serif;
  --display: "IBM Plex Sans Condensed", "IBM Plex Sans", system-ui, "Segoe UI", Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "Cascadia Mono", Consolas, monospace;
  --maxw: 1120px;
  --focus: 3px solid var(--accent);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101417;
    --bg-raised: #171d21;
    --bg-band: #141a1e;
    --line: #2a343a;
    --line-strong: #43525a;
    --grid: rgba(233, 238, 240, 0.055);

    --ink: #e9eef0;
    --ink-soft: #a9b6bc;

    --accent: #3cc3c9;
    --accent-ink: #86e3e3;
    --accent-soft: #12302f;

    --btn-bg: #3cc3c9;
    --btn-fg: #04282a;
    --btn-bg-hover: #6ad8dc;
    --on-accent: #04282a;
    --ghost-fg: #86e3e3;
    --ghost-border: #3cc3c9;
    --ghost-hover-bg: #12302f;

    --footer-bg: #0a0d0f;
    --footer-fg: #dfe5e7;
    --footer-muted: #93a1a8;
    --footer-link: #9be6e6;
    --footer-line: #232c31;
    --tip-bg: #e9eef0;
    --tip-fg: #101417;

    --warn-bg: #2e2610;
    --warn-ink: #f0d58a;
    --warn-line: #5a4a1c;
    --error-ink: #ff9d92;
    --ok-ink: #8fe0ae;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 5rem; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  line-height: 1.65;
  font-size: 17px;
  overflow-x: clip;
}
img, svg { max-width: 100%; height: auto; display: block; }
h1, h2, h3 { font-family: var(--display); line-height: 1.15; letter-spacing: -0.005em; }
h1, h2 { font-weight: 700; text-wrap: balance; }
h3 { font-weight: 600; font-family: var(--sans); letter-spacing: 0; }
a { color: var(--accent-ink); text-decoration-thickness: 1.5px; text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2.5px; }
:focus-visible { outline: var(--focus); outline-offset: 3px; border-radius: 3px; }
code, .mono, .kicker, .tag, .step-label, .label { font-family: var(--mono); }

.skip-link { position: absolute; left: -999px; top: 0; background: var(--btn-bg); color: var(--btn-fg); padding: .6rem 1rem; z-index: 100; }
.skip-link:focus { left: 1rem; top: 1rem; }

.wrap { max-width: var(--maxw); margin-inline: auto; padding-inline: 1.25rem; }

/* ---------- Header ---------- */
.site-header { border-bottom: 1px solid var(--line); background: var(--bg-raised); position: sticky; top: 0; z-index: 20; }
@supports (background: color-mix(in srgb, red 50%, blue)) {
  .site-header { background: color-mix(in srgb, var(--bg-raised) 90%, transparent); backdrop-filter: blur(10px); }
}
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; padding-block: .8rem; gap: 1rem; }
.brand { display: inline-flex; align-items: center; gap: .6rem; font-family: var(--display); font-weight: 700; font-size: 1.4rem; color: var(--ink); text-decoration: none; letter-spacing: -.01em; }
.brand-mark { display: inline-grid; place-items: center; width: 2rem; height: 2rem; border-radius: 7px; background: var(--btn-bg); color: var(--btn-fg); font-family: var(--mono); font-weight: 500; font-size: .85rem; letter-spacing: -.04em; }
nav.main-nav ul { list-style: none; display: flex; gap: .3rem; margin: 0; padding: 0; flex-wrap: wrap; }
nav.main-nav a { display: block; color: var(--ink); text-decoration: none; font-size: .95rem; padding: .4rem .7rem; border-radius: 999px; }
nav.main-nav a:hover { background: var(--accent-soft); color: var(--accent-ink); }
nav.main-nav a[aria-current="page"] { background: var(--accent-soft); color: var(--accent-ink); font-weight: 600; }
@media (max-width: 760px) {
  .site-header { position: static; }
  .site-header .wrap { flex-wrap: wrap; }
  nav.main-nav ul { gap: .15rem; margin-inline: -.7rem; }
}

/* ---------- Footer ---------- */
.site-footer { background: var(--footer-bg); color: var(--footer-fg); margin-top: 4rem; }
.site-footer a { color: var(--footer-link); }
.site-footer a:hover { color: var(--footer-fg); }
.site-footer :focus-visible { outline-color: var(--footer-link); }
.footer-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 2rem; padding: 3rem 1.25rem 2.2rem; }
.footer-grid .footer-title { font-family: var(--mono); font-weight: 500; font-size: .85rem; color: var(--footer-muted); margin: 0 0 .9rem; letter-spacing: 0; }
.footer-grid ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: .5rem; font-size: .93rem; }
.footer-bottom { border-top: 1px solid var(--footer-line); padding: 1.1rem 1.25rem 1.6rem; font-size: .86rem; color: var(--footer-muted); display: flex; justify-content: space-between; flex-wrap: wrap; gap: .5rem; }
@media (max-width: 760px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .footer-grid { grid-template-columns: 1fr; } }

/* ---------- Labels ---------- */
.kicker { display: inline-flex; align-items: center; gap: .55rem; margin: 0; color: var(--accent-ink); font-size: .84rem; font-weight: 500; }
.kicker::before { content: ""; width: 1.1rem; height: 2px; background: var(--accent); }
.tag, .pill { display: inline-block; font-family: var(--mono); font-size: .75rem; padding: .15rem .55rem; border: 1px solid var(--line-strong); border-radius: 999px; background: transparent; color: var(--ink-soft); }
.tag.level-beginner { border-color: var(--accent); color: var(--accent-ink); background: var(--accent-soft); }
.tag.level-intermediate { border-color: var(--line-strong); color: var(--ink); }

/* ---------- Buttons ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: .45rem; padding: .7rem 1.3rem; border-radius: 999px; text-decoration: none; font-weight: 600; font-size: .96rem; font-family: var(--sans); border: 1.5px solid transparent; cursor: pointer; line-height: 1.3; }
.btn-primary { background: var(--btn-bg); color: var(--btn-fg); border-color: var(--btn-bg); }
.btn-primary:hover { background: var(--btn-bg-hover); border-color: var(--btn-bg-hover); color: var(--btn-fg); text-decoration: none; }
.btn-ghost { background: transparent; color: var(--ghost-fg); border-color: var(--ghost-border); }
.btn-ghost:hover { background: var(--ghost-hover-bg); color: var(--ghost-fg); text-decoration: none; }
.btn:focus-visible { outline: var(--focus); outline-offset: 3px; }

/* ---------- Page title band (all inner pages) ---------- */
.page-head { position: relative; isolation: isolate; padding-block: 2.6rem 2.2rem; }
/* Full-bleed band: 100cqw = width of <main> (no scrollbar), so it never causes sideways scrolling. */
main { container-type: inline-size; }
.page-head::before {
  content: ""; position: absolute; z-index: -1; top: 0; bottom: 0;
  left: calc(50% - 50vw); right: calc(50% - 50vw);
  left: calc(50% - 50cqw); right: calc(50% - 50cqw);
  background-color: var(--bg-band);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 28px 28px;
  border-bottom: 1px solid var(--line);
}
.page-head h1 { font-size: clamp(2.1rem, 4.6vw, 3.2rem); margin: .8rem 0 .8rem; line-height: 1.04; }
.page-head .lede { font-size: 1.15rem; color: var(--ink-soft); max-width: 40rem; margin: 0; }
.breadcrumbs + .page-head { margin-top: .6rem; }

.hero { padding-block: 3rem 2.4rem; }
.hero h1 { font-size: clamp(2.1rem, 4.6vw, 3.2rem); margin: .6rem 0 1rem; line-height: 1.04; }
.hero p.lede { font-size: 1.15rem; color: var(--ink-soft); max-width: 40rem; }
.hero-actions { display: flex; gap: .8rem; margin-top: 1.6rem; flex-wrap: wrap; }

/* ---------- Home hero ---------- */
.home-hero { position: relative; isolation: isolate; border-bottom: 1px solid var(--line); background: var(--bg-band); }
.home-hero::before {
  content: ""; position: absolute; inset: 0; z-index: -1;
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 32px 32px;
}
.home-hero-grid { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr); gap: 3rem; align-items: center; padding-block: 3.6rem 3.8rem; }
.home-hero h1 { font-size: clamp(2.5rem, 5.6vw, 4.2rem); line-height: 1; margin: 1rem 0 1.2rem; letter-spacing: -.012em; }
.home-hero .lede { font-size: 1.2rem; color: var(--ink-soft); max-width: 34rem; margin: 0; }
.hero-figure { margin: 0; background: var(--bg-raised); border: 1px solid var(--line-strong); border-radius: var(--radius); padding: 1rem 1rem .8rem; }
.hero-figure svg { width: 100%; max-height: 420px; }
.hero-figure figcaption { font-family: var(--mono); font-size: .78rem; color: var(--ink-soft); padding-top: .6rem; border-top: 1px dashed var(--line-strong); margin-top: .4rem; }
@media (max-width: 900px) {
  .home-hero-grid { grid-template-columns: 1fr; gap: 2rem; padding-block: 2.4rem 2.6rem; }
}

/* hero figure palette */
.hx-top { fill: var(--bg-raised); stroke: var(--ink); stroke-width: 1.4; stroke-linejoin: round; }
.hx-top.hx-accent { fill: var(--accent-soft); stroke: var(--accent-ink); }
.hx-left { fill: var(--line); stroke: var(--ink); stroke-width: 1.4; stroke-linejoin: round; }
.hx-right { fill: var(--line-strong); stroke: var(--ink); stroke-width: 1.4; stroke-linejoin: round; }
.hx-detail { fill: none; stroke: var(--ink-soft); stroke-width: 1.2; }
.hx-detail.hx-accent { stroke: var(--accent-ink); }
.hx-dot { fill: var(--accent-ink); }
.hx-guide { stroke: var(--line-strong); stroke-width: 1.2; stroke-dasharray: 4 5; }
.hx-leader { stroke: var(--ink-soft); stroke-width: 1.2; }
.hx-label { font-family: var(--mono); font-size: 13.5px; fill: var(--ink); }
@media (max-width: 600px) { .hx-label { font-size: 17px; } }

/* ---------- Photos (Pexels, credited under every photo) ---------- */
.has-photo { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); gap: 1.6rem 2.6rem; align-items: center; }
.head-photo { margin: 0; min-width: 0; }
.head-text { min-width: 0; }
.head-photo img { width: 100%; max-width: 100%; height: auto; aspect-ratio: 1200 / 630; object-fit: cover; border-radius: var(--radius); border: 1px solid var(--line-strong); background: var(--bg-raised); }
.head-photo figcaption { font-family: var(--mono); font-size: .76rem; color: var(--ink-soft); margin-top: .5rem; }
.head-photo figcaption a { color: inherit; }
.card-thumb { display: block; width: calc(100% + 2.6rem); max-width: none; height: auto; aspect-ratio: 480 / 252; object-fit: cover; margin: -1.3rem -1.3rem 1.1rem; border-radius: var(--radius) var(--radius) 0 0; background: var(--accent-soft); }
.card { overflow: hidden; }
/* minmax(0, 1fr): a plain 1fr lets the 1200px-wide photo stretch the column wider than the phone screen */
@media (max-width: 860px) { .has-photo { grid-template-columns: minmax(0, 1fr); } }

/* ---------- Sections and grids ---------- */
.section { padding-block: 3rem; }
.section-head { display: flex; align-items: baseline; justify-content: space-between; gap: 1rem; margin-bottom: 1.5rem; flex-wrap: wrap; }
.section-head h2 { margin: 0; font-size: clamp(1.6rem, 3vw, 2.1rem); }
.section-lede { color: var(--ink-soft); max-width: 40rem; margin: -.8rem 0 1.5rem; }
.grid-5 { display: grid; grid-template-columns: repeat(5, 1fr); gap: 1rem; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.1rem; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.1rem; }
@media (max-width: 960px) { .grid-5 { grid-template-columns: repeat(2, 1fr); } .grid-3 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .grid-5, .grid-3, .grid-2 { grid-template-columns: 1fr; } }

.card { background: var(--bg-raised); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.3rem 1.3rem 1.2rem; text-decoration: none; color: var(--ink); display: block; transition: border-color .15s ease; }
.card:hover { border-color: var(--accent); }
.card h3 { margin: .7rem 0 .45rem; font-size: 1.1rem; line-height: 1.3; }
.card p { margin: 0; color: var(--ink-soft); font-size: .94rem; }
.card:hover h3 { text-decoration: underline; text-decoration-color: var(--accent); text-underline-offset: 3px; text-decoration-thickness: 2px; }
.card .tag { margin-bottom: 0; }
.card .kicker { margin-top: .9rem; }

.cat-card { padding-top: 1.4rem; }
.cat-card h3 { margin-top: 1rem; }
.cat-icon { display: inline-grid; place-items: center; width: 2.8rem; height: 2.8rem; border-radius: 10px; background: var(--accent-soft); color: var(--accent-ink); }
.cat-icon svg { width: 1.6rem; height: 1.6rem; }
.cat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.1rem; }
.promo-card { background: var(--btn-bg); border-color: var(--btn-bg); color: var(--btn-fg); display: flex; flex-direction: column; justify-content: space-between; }
.promo-card h3, .promo-card p { color: var(--btn-fg); }
.promo-card p { opacity: .92; }
.promo-card:hover { border-color: var(--btn-bg-hover); background: var(--btn-bg-hover); }
.promo-card .promo-link { margin-top: 1.2rem; font-weight: 600; text-decoration: underline; text-underline-offset: 3px; }
@media (max-width: 960px) { .cat-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .cat-grid { grid-template-columns: 1fr; } }

/* ---------- Breadcrumbs ---------- */
.breadcrumbs { font-size: .86rem; color: var(--ink-soft); padding-top: 1rem; }
.breadcrumbs ol { list-style: none; display: flex; gap: .45rem; flex-wrap: wrap; margin: 0; padding: 0; }
.breadcrumbs li:not(:last-child)::after { content: "/"; margin-left: .45rem; color: var(--line-strong); }
.breadcrumbs a { color: var(--ink-soft); text-decoration: none; }
.breadcrumbs a:hover { color: var(--accent-ink); text-decoration: underline; }

/* ---------- Article ---------- */
.article-head { position: relative; isolation: isolate; padding-block: 2.2rem 1.8rem; margin-top: .6rem; }
.article-head::before {
  content: ""; position: absolute; z-index: -1; top: 0; bottom: 0;
  left: calc(50% - 50vw); right: calc(50% - 50vw);
  left: calc(50% - 50cqw); right: calc(50% - 50cqw);
  background-color: var(--bg-band);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 28px 28px; border-bottom: 1px solid var(--line);
}
.article-head h1 { font-size: clamp(2rem, 4.2vw, 3rem); margin: .8rem 0 1rem; line-height: 1.06; max-width: 22ch; }
.article-meta { display: flex; gap: .6rem; flex-wrap: wrap; align-items: center; color: var(--ink-soft); font-size: .88rem; }
.article-body { max-width: 44rem; padding-block: 2.2rem 1rem; }
.article-body > p:first-child { font-size: 1.15rem; color: var(--ink); }
.article-body h2 { font-size: 1.6rem; margin: 2.6rem 0 .8rem; padding-top: 1.6rem; border-top: 1px solid var(--line); }
.article-body p { margin: 0 0 1.05rem; }
.article-body ol, .article-body ul { padding-left: 1.3rem; }
.article-body li { margin-bottom: .4rem; }
.limits-box { background: var(--warn-bg); color: var(--warn-ink); border: 1px solid var(--warn-line); border-left: 4px solid var(--warn-ink); border-radius: var(--radius-sm); padding: 1rem 1.2rem; margin: 1.8rem 0; font-size: .93rem; }
.limits-box strong { display: block; margin-bottom: .3rem; font-family: var(--mono); font-weight: 500; }
.mistakes-box { background: var(--bg-raised); border: 1px solid var(--line); border-left: 4px solid var(--accent); border-radius: var(--radius-sm); padding: 1.2rem 1.4rem; margin: 2.2rem 0; }
.mistakes-box h2 { margin: 0 0 .4rem; padding: 0; border: 0; font-size: 1.35rem; }
.mistakes-box ul { margin: .4rem 0 0; padding-left: 1.2rem; }
.table-scroll { overflow-x: auto; margin: 1.2rem 0; border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--bg-raised); }
table.data-table { width: 100%; min-width: 480px; border-collapse: collapse; margin: 0; font-size: .93rem; }
table.data-table th, table.data-table td { border-bottom: 1px solid var(--line); padding: .7rem .85rem; text-align: left; vertical-align: top; }
table.data-table tbody tr:last-child td { border-bottom: 0; }
table.data-table th { background: var(--accent-soft); color: var(--accent-ink); font-family: var(--mono); font-weight: 500; font-size: .82rem; }
.checklist, .article-body .checklist { list-style: none; margin: 1rem 0; padding: 0; }
.checklist li { display: flex; gap: .7rem; padding: .6rem 0; border-bottom: 1px dashed var(--line-strong); }
.checklist input[type="checkbox"] { width: 1.15rem; height: 1.15rem; accent-color: var(--accent); margin-top: .25rem; flex: none; }
.print-btn { font-family: var(--mono); font-size: .84rem; }
.faq-item { border-bottom: 1px solid var(--line); padding: 1.1rem 0; }
.faq-item h3 { margin: 0 0 .4rem; font-size: 1.05rem; }
.faq-item p { margin: 0 0 .5rem; }
.sources-list { font-size: .9rem; color: var(--ink-soft); padding-left: 1.2rem; overflow-wrap: anywhere; }
.related-links { display: flex; flex-wrap: wrap; gap: .6rem; margin-bottom: 1.4rem; }
.related-links a { font-size: .9rem; text-align: left; }
.transparency-block { background: var(--accent-soft); border-left: 4px solid var(--accent); border-radius: var(--radius-sm); padding: 1.6rem 1.8rem; }
.transparency-block h2 { margin-top: 0; }
.transparency-block p:last-child { margin-bottom: 0; }

/* ---------- Glossary term + tooltip ---------- */
.gterm { border-bottom: 1.5px dotted var(--accent); cursor: help; position: relative; color: var(--ink); text-decoration: none; }
.gterm:focus-visible, .gterm:hover { color: var(--accent-ink); }
.gtooltip { display: none; position: absolute; left: 0; top: 1.6em; z-index: 30; width: min(280px, 80vw); background: var(--tip-bg); color: var(--tip-fg); padding: .75rem .95rem; border-radius: 8px; font-size: .86rem; line-height: 1.45; font-family: var(--sans); font-weight: 400; box-shadow: 0 10px 28px rgba(0, 0, 0, .28); }
.gterm[data-open="true"] .gtooltip { display: block; }

/* ---------- Trails ---------- */
.trail-intro { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr); gap: 2.5rem; align-items: start; }
.trail-intro h2 { margin: 0 0 .8rem; font-size: clamp(1.7rem, 3vw, 2.2rem); }
.steps-plain { list-style: none; counter-reset: sp; padding: 0; margin: 1.3rem 0 1.6rem; }
.steps-plain li { counter-increment: sp; display: grid; grid-template-columns: 2rem 1fr; gap: .8rem; padding: .7rem 0; border-top: 1px solid var(--line); }
.steps-plain li:last-child { border-bottom: 1px solid var(--line); }
.steps-plain li::before { content: counter(sp); font-family: var(--mono); font-size: .85rem; display: grid; place-items: center; width: 1.7rem; height: 1.7rem; border-radius: 50%; background: var(--accent-soft); color: var(--accent-ink); }
.trail-preview { background: var(--bg-raised); border: 1px solid var(--line-strong); border-radius: var(--radius); padding: 1.3rem 1.4rem; }
.trail-preview h3 { font-family: var(--mono); font-weight: 500; font-size: .85rem; color: var(--accent-ink); margin: 0 0 .8rem; }
.trail-preview ol { margin: 0 0 1rem; padding-left: 1.4rem; }
.trail-preview li { padding: .45rem 0; border-bottom: 1px dashed var(--line); }
.trail-preview li:last-child { border-bottom: 0; color: var(--ink-soft); }
@media (max-width: 860px) { .trail-intro { grid-template-columns: 1fr; gap: 1.8rem; } }

.what-is { background: var(--accent-soft); border-left: 4px solid var(--accent); border-radius: var(--radius-sm); padding: 1rem 1.3rem; margin-bottom: 1.6rem; font-size: .96rem; }
.what-is p { margin: 0; }
.trail-progress-wrap { background: var(--bg-raised); border: 1px solid var(--line-strong); border-radius: var(--radius); padding: 1.3rem 1.5rem; margin-bottom: 1.6rem; }
.trail-progress-head { display: flex; justify-content: space-between; align-items: baseline; gap: 1rem; flex-wrap: wrap; }
.progress-status { margin: 0; font-family: var(--mono); font-size: .9rem; color: var(--ink-soft); }
.progress-bar { height: 12px; background: var(--line); border-radius: 999px; overflow: hidden; margin: .7rem 0 1rem; }
.progress-bar-fill { height: 100%; background: var(--accent); width: 0%; transition: width .3s ease; border-radius: 999px; }
.trail-steps { list-style: none; margin: 0; padding: 0; display: grid; gap: .8rem; }
.trail-step { display: grid; grid-template-columns: 3rem 1fr auto; gap: 1rem; align-items: center; padding: 1.1rem 1.3rem; background: var(--bg-raised); border: 1px solid var(--line); border-radius: var(--radius); }
.trail-step:has(input:checked) { border-color: var(--accent); background: var(--accent-soft); }
.step-num { font-family: var(--display); font-weight: 700; font-size: 1.9rem; line-height: 1; color: var(--accent-ink); }
.trail-step-title { display: block; font-weight: 600; font-size: 1.05rem; margin-bottom: .45rem; }
.step-mark { display: inline-flex; align-items: center; gap: .55rem; font-size: .9rem; color: var(--ink); cursor: pointer; padding: .4rem .7rem; border: 1px solid var(--line-strong); border-radius: 999px; white-space: nowrap; }
.step-mark input { width: 1.1rem; height: 1.1rem; accent-color: var(--accent); }
@media (max-width: 600px) {
  .trail-step { grid-template-columns: 2.2rem 1fr; }
  .step-mark { grid-column: 2; justify-self: start; }
}
.data-note { font-size: .88rem; color: var(--ink-soft); background: var(--bg-raised); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: .9rem 1.1rem; margin-block: 1rem; }

/* ---------- Forms and Explorer ---------- */
input[type="text"], input[type="email"], input[type="search"], select, textarea {
  width: 100%; font: inherit; font-size: .98rem; color: var(--ink); background: var(--bg-raised);
  border: 1px solid var(--line-strong); border-radius: 8px; padding: .62rem .75rem;
}
input::placeholder, textarea::placeholder { color: var(--ink-soft); opacity: .8; }
label { font-size: .88rem; }
.explorer-controls { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 1rem; background: var(--bg-raised); border: 1px solid var(--line-strong); border-radius: var(--radius); padding: 1.2rem; }
.explorer-controls label { font-size: .8rem; font-family: var(--mono); color: var(--ink-soft); display: block; margin-bottom: .35rem; }
@media (max-width: 760px) { .explorer-controls { grid-template-columns: 1fr 1fr; } .explorer-controls > div:first-child { grid-column: 1 / -1; } }
#results-status { font-family: var(--mono); font-size: .88rem; color: var(--ink-soft); margin: 1rem 0; }
.empty-state { text-align: center; padding: 2.5rem 1rem; color: var(--ink-soft); }
.form-stack { display: grid; gap: 1.1rem; }
.form-stack label { display: block; margin-bottom: .35rem; font-weight: 600; }
.form-status { min-height: 1.5rem; margin: 0; font-weight: 600; }
.form-status.is-error { color: var(--error-ink); }
.form-status.is-ok { color: var(--ok-ink); }

/* ---------- Diagrams ---------- */
.diagram-wrap { background: var(--bg-raised); border: 1px solid var(--line-strong); border-radius: var(--radius); padding: 1.2rem; margin: 2rem 0; max-width: 52rem; }
.svg-scroll { overflow-x: auto; border-radius: var(--radius-sm); }
.diagram-wrap svg {
  width: 100%; border: 1px solid var(--line); border-radius: var(--radius-sm); background-color: var(--bg);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 20px 20px;
}
.svg-scroll svg { min-width: 560px; }
.swipe-hint { display: none; font-family: var(--mono); font-size: .78rem; color: var(--ink-soft); margin: .4rem 0 0; }
@media (max-width: 640px) { .swipe-hint { display: block; } }
.diagram-controls { display: flex; gap: .5rem; align-items: center; margin-top: 1rem; flex-wrap: wrap; }
.diagram-controls button { font-family: var(--mono); font-size: .82rem; padding: .45rem .85rem; border: 1.5px solid var(--ghost-border); background: transparent; color: var(--ghost-fg); border-radius: 999px; cursor: pointer; }
.diagram-controls button:hover { background: var(--ghost-hover-bg); }
.diagram-controls button[aria-pressed="true"] { background: var(--btn-bg); border-color: var(--btn-bg); color: var(--btn-fg); }
.diagram-caption { font-size: .93rem; color: var(--ink-soft); margin: .9rem 0 0; }
.diagram-controls + .diagram-caption { margin-top: 1.2rem; }
.diagram-caption[data-step-caption] { color: var(--ink); min-height: 3.2em; }
details.diagram-caption { margin-top: .6rem; }
details.diagram-caption summary { cursor: pointer; font-family: var(--mono); font-size: .85rem; color: var(--accent-ink); }
.diagram-fallback-note { font-size: .8rem; color: var(--ink-soft); }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: .001ms !important; transition-duration: .001ms !important; scroll-behavior: auto !important; }
}

/* Shared SVG diagram palette classes (all follow the light/dark tokens) */
.dg-ink { fill: var(--ink); }
.dg-soft { fill: var(--ink-soft); }
.dg-accent-fill { fill: var(--accent); }
.dg-accent-stroke { stroke: var(--accent-ink); }
.dg-accent2 { fill: var(--accent-ink); }
.dg-line-stroke { stroke: var(--ink-soft); }
.dg-surface { fill: var(--bg-raised); stroke: var(--line-strong); }
.dg-bg { fill: var(--bg); }
.dg-label { font-family: var(--mono); font-size: 11px; fill: var(--ink-soft); }
.dg-label-strong { font-family: var(--mono); font-size: 12px; fill: var(--ink); font-weight: 500; }
.dg-on-ink { fill: var(--bg); }              /* text drawn on a .dg-ink shape */
.dg-on-accent { fill: var(--on-accent); }    /* text drawn on a .dg-accent2 shape */
.dg-select { fill: none; stroke: var(--ink); }
.dg-r { fill: #b3261e; } .dg-g { fill: #1b6b3a; } .dg-b { fill: #1f5f99; }
.dg-white { fill: #ffffff; }                 /* text on the fixed R/G/B swatches (same in both themes) */
.dg-txt-r { fill: #b3261e; } .dg-txt-g { fill: #1b6b3a; } .dg-txt-b { fill: #1f5f99; }
.dg-step-group { transition: opacity .15s ease; }
.dg-step-group[hidden] { display: none; }
.dg-dashed { stroke-dasharray: 4 4; }
@media (prefers-color-scheme: dark) {
  .dg-txt-r { fill: #ff9a90; } .dg-txt-g { fill: #7fdc9f; } .dg-txt-b { fill: #8ec3f4; }
}

/* ---------- Print ---------- */
@media print {
  .site-header, .site-footer, .no-print, .diagram-controls, .explorer-controls { display: none !important; }
  body { background: #fff; color: #000; }
  .article-body { max-width: none; }
  .page-head::before, .article-head::before { display: none; }
}