/* ---------- Sigrix Learn — shared sub-page template ----------
 * Lifted from Sigrix_new/Sigrix Learn Article.html and
 * Sigrix Building Blocks.html. These art-* patterns are the common
 * chrome for every page that lives under /learn (the article shell,
 * breadcrumb header, sticky TOC, end-of-article rail, related cards
 * and newsletter strip). Used by both the Building Blocks page and
 * the long-form learn articles.
 *
 * Theming convention matches the rest of the app: light is the base
 * cascade (.sx), dark is layered on via [data-theme="dark"] .sx. The
 * base --sx-* tokens come from sx-home.css; here we only add the
 * category accents and the per-article accent. */

.sx {
  --cat-foundations: #2A33C4;
  --cat-tutorials:   #0F766E;
  --cat-patterns:    #6D28D9;
  --cat-seller:      #B91C5C;
  --cat-buyer:       #1F9D55;
  --cat-case:        #B7791F;

  --art-accent: var(--cat-foundations);
  --art-accent-tint: rgba(42,51,196,0.08);

  --sx-font-num: 'Space Grotesk', 'Geist', ui-sans-serif, system-ui, sans-serif;
}
[data-theme="dark"] .sx {
  --cat-foundations: #6B78FF;
  --cat-tutorials:   #7CE3D4;
  --cat-patterns:    #B48CFF;
  --cat-seller:      #F47B7B;
  --cat-buyer:       #6EE7A1;
  --cat-case:        #F5B454;

  --art-accent: var(--cat-foundations);
  --art-accent-tint: rgba(107,120,255,0.10);
}

/* ─────────── Reading progress bar ─────────── */
.art-progress {
  position: fixed; top: 0; left: 0; right: 0; height: 2px; z-index: 60;
  background: transparent;
}
.art-progress .bar {
  height: 100%;
  background: linear-gradient(90deg, var(--sx-brand-3), var(--sx-accent));
  width: 0%;
  transition: width 80ms linear;
}

/* ─────────── Breadcrumb ─────────── */
.art-breadcrumb {
  padding: 28px 0 0;
  font-family: var(--sx-font-mono); font-size: 11px;
  color: var(--sx-text-3); letter-spacing: 0.06em;
}
.art-breadcrumb a { color: var(--sx-text-2); transition: color 120ms; }
.art-breadcrumb a:hover { color: var(--sx-text); }
.art-breadcrumb .sep { color: var(--sx-mute); padding: 0 6px; }
.art-breadcrumb .here { color: var(--sx-text); }

/* ─────────── Header ─────────── */
/* On article pages the gradient header sits flush against the nav;
 * the nav's default border-bottom would draw a hard line between them. */
.learn-article-page .sx-nav { border-bottom: 0; }

/* The full-viewport breakout — so the gradient spans the viewport instead of
 * stopping at the 1200px `.container` box — comes from the shared `.art-header`
 * entry in the `.sx-bleed` rule in sx-home.css (#3080). The inner
 * `.sx-container` keeps content centered. */
.art-header {
  padding: 32px 0 40px;
  position: relative;
}
.art-header-bg {
  position: absolute; inset: 0; pointer-events: none;
  background: radial-gradient(800px 280px at 80% 0%, var(--art-accent-tint), transparent 60%);
}
.art-header-inner { position: relative; max-width: 760px; margin: 0 auto; }
.art-cat {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--sx-font-mono); font-size: 11px; font-weight: 600;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--art-accent);
}
.art-cat .dot { width: 8px; height: 8px; border-radius: 2px; background: currentColor; }
.art-title {
  margin-top: 18px;
  font-size: 52px; font-weight: 600; letter-spacing: -0.035em; line-height: 1.05;
  text-wrap: balance;
}
.art-title .accent {
  color: var(--sx-text-3);
  font-style: italic;
  font-weight: 500;
}
.art-lede {
  margin-top: 20px; font-size: 19px; color: var(--sx-text-2); line-height: 1.55;
  max-width: 60ch;
}
.art-meta-row {
  margin-top: 26px;
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
  font-family: var(--sx-font-mono); font-size: 11px; color: var(--sx-text-3);
  letter-spacing: 0.04em;
}
.art-meta-row .sep { width: 4px; height: 4px; border-radius: 50%; background: var(--sx-line-2); }
.art-author {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--sx-text-2);
}
.art-author .av {
  width: 28px; height: 28px; border-radius: 50%;
  background: linear-gradient(135deg, #3D4DFF, #1A1F6B);
  display: inline-flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 600; font-size: 11px;
  font-family: var(--sx-font-body);
}
.art-author .nm {
  font-size: 13px; color: var(--sx-text); font-family: var(--sx-font-body);
  letter-spacing: -0.005em; font-weight: 500;
}
.art-meta-actions {
  margin-top: 22px; padding-top: 22px;
  border-top: 1px solid var(--sx-line);
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
}
.art-share-btn {
  display: inline-flex; align-items: center; gap: 6px;
  height: 34px; min-height: 0; padding: 0 12px;
  border: 0; border-radius: var(--sx-r-sm);
  font-family: inherit; font-size: 12px; font-weight: 500;
  color: var(--sx-text-2);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  cursor: pointer;
  transition: color 120ms, box-shadow 120ms, background 120ms;
}
.art-share-btn:hover { color: var(--sx-text); box-shadow: 0 0 0 1px var(--sx-line-2) inset; }
.art-share-btn svg { width: 14px; height: 14px; }
.art-share-btn.copied { color: var(--sx-ok); }
.art-share-btn--push { margin-left: auto; }

/* ─────────── Horizontal TOC strip (sticky, below nav) ─────────── */
.art-toc-strip {
  position: sticky; top: 60px; z-index: 4;
  background: rgba(250,250,251,0.88);
  backdrop-filter: blur(14px) saturate(120%);
  -webkit-backdrop-filter: blur(14px) saturate(120%);
  border-top: 1px solid var(--sx-line);
  border-bottom: 1px solid var(--sx-line);
}
[data-theme="dark"] .sx .art-toc-strip { background: rgba(11,13,18,0.82); }
.art-toc-strip-inner {
  display: flex; align-items: center; gap: 14px;
  padding: 12px 0;
  overflow-x: auto; scrollbar-width: none;
}
.art-toc-strip-inner::-webkit-scrollbar { display: none; }
.art-toc-strip-label {
  font-family: var(--sx-font-mono); font-size: 10px;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--sx-text-3); white-space: nowrap;
  padding-right: 8px; border-right: 1px solid var(--sx-line);
}
.art-toc-link {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 13px; color: var(--sx-text-2); font-weight: 500;
  padding: 6px 4px; white-space: nowrap;
  border-radius: 4px;
  transition: color 120ms;
  position: relative;
}
.art-toc-link .n {
  font-family: var(--sx-font-mono); font-size: 10px; color: var(--sx-text-3);
  letter-spacing: 0.04em;
}
.art-toc-link:hover { color: var(--sx-text); }
.art-toc-link.active { color: var(--art-accent); }
.art-toc-link.active .n { color: var(--art-accent); }
.art-toc-link.active::after {
  content: ""; position: absolute; left: 4px; right: 4px; bottom: -13px;
  height: 2px; background: var(--art-accent); border-radius: 2px;
}

/* ─────────── Layout grid: content + sidebar TOC ─────────── */
.art-shell {
  display: grid;
  grid-template-columns: minmax(0, 760px) 240px;
  gap: 64px;
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 32px 80px;
  align-items: start;
}
.art-content { min-width: 0; }
.art-aside { position: sticky; top: 84px; align-self: start; }

.art-toc {
  padding: 18px;
  border-radius: var(--sx-r-md);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
}
.art-toc h4 {
  font-family: var(--sx-font-mono); font-size: 10px; font-weight: 600;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--sx-text-3); margin-bottom: 12px;
}
.art-toc ol {
  list-style: none; padding: 0; margin: 0;
  display: flex; flex-direction: column; gap: 2px;
  counter-reset: toc;
}
.art-toc li { counter-increment: toc; }
.art-toc a {
  display: grid; grid-template-columns: 26px 1fr; gap: 8px; align-items: start;
  padding: 8px 6px 8px 0;
  border-radius: var(--sx-r-sm);
  font-size: 13px; color: var(--sx-text-2);
  line-height: 1.4;
  transition: color 120ms, background 120ms;
}
.art-toc a::before {
  content: counter(toc, decimal-leading-zero);
  font-family: var(--sx-font-mono); font-size: 10px;
  color: var(--sx-text-3); letter-spacing: 0.04em;
  padding-top: 2px;
}
.art-toc a:hover { color: var(--sx-text); }
.art-toc a.active { color: var(--art-accent); }
.art-toc a.active::before { color: var(--art-accent); }

.art-aside-stats {
  margin-top: 12px;
  display: flex; justify-content: space-between; gap: 10px;
  padding: 14px 16px;
  border-radius: var(--sx-r-md);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  font-family: var(--sx-font-mono); font-size: 10px;
  color: var(--sx-text-3); letter-spacing: 0.06em;
}
.art-aside-stats .stat { display: flex; flex-direction: column; gap: 2px; }
.art-aside-stats .stat b { color: var(--sx-text); font-size: 16px; font-family: var(--sx-font-num); letter-spacing: -0.01em; font-weight: 600; }

/* ─────────── Article body typography ─────────── */
.art-body { font-size: 17px; line-height: 1.7; color: var(--sx-text); }
.art-body > * + * { margin-top: 22px; }
.art-body h2 {
  font-size: 30px; font-weight: 600; letter-spacing: -0.02em;
  margin-top: 56px;
  scroll-margin-top: 80px;
  display: flex; align-items: baseline; gap: 14px;
}
.art-body h2 .hnum {
  font-family: var(--sx-font-mono); font-size: 11px;
  color: var(--art-accent); letter-spacing: 0.10em; font-weight: 600;
  padding-top: 6px;
  flex-shrink: 0;
}
.art-body h3 {
  font-size: 20px; font-weight: 600; letter-spacing: -0.015em;
  margin-top: 32px; color: var(--sx-text);
  scroll-margin-top: 80px;
}
.art-body p { color: var(--sx-text-2); font-size: 17px; line-height: 1.7; }
.art-body p b { color: var(--sx-text); font-weight: 600; }
.art-body p.lead { font-size: 18px; color: var(--sx-text); font-weight: 500; }
.art-body a.inline {
  color: var(--art-accent);
  border-bottom: 1px solid color-mix(in oklab, var(--art-accent) 50%, transparent);
  padding-bottom: 1px;
}
.art-body a.inline:hover { border-bottom-color: var(--art-accent); }
.art-body ul, .art-body ol {
  padding-left: 20px; color: var(--sx-text-2);
  display: flex; flex-direction: column; gap: 8px;
}
.art-body ul li::marker { color: var(--art-accent); }
.art-body ol li::marker { color: var(--sx-text-3); font-family: var(--sx-font-mono); font-size: 14px; }
.art-body li b { color: var(--sx-text); font-weight: 600; }

.art-body blockquote {
  margin: 32px 0;
  padding: 22px 26px;
  background: var(--sx-surface);
  border-radius: var(--sx-r-md);
  box-shadow: 0 0 0 1px var(--sx-line) inset, inset 4px 0 0 var(--art-accent);
  font-size: 19px; line-height: 1.6; color: var(--sx-text);
  letter-spacing: -0.005em;
}
.art-body blockquote .attrib {
  display: block; margin-top: 12px;
  font-family: var(--sx-font-mono); font-size: 11px;
  color: var(--sx-text-3); letter-spacing: 0.04em;
}

/* Code block */
.art-code {
  font-family: var(--sx-font-mono);
  font-size: 13px;
  line-height: 1.65;
  padding: 18px 22px;
  background: var(--sx-bg-2);
  border-radius: var(--sx-r-md);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  color: var(--sx-text-2);
  white-space: pre;
  overflow-x: auto;
  position: relative;
}
.art-code .filename {
  position: absolute; top: 10px; right: 16px;
  font-size: 10px; color: var(--sx-text-3); letter-spacing: 0.08em;
  text-transform: uppercase;
}
.art-code .k { color: var(--sx-brand-3); }
.art-code .s { color: var(--sx-accent); }
.art-code .n { color: var(--sx-warn); }
.art-code .c { color: var(--sx-text-3); }

/* Comparison table */
.art-compare {
  margin: 32px 0;
  border-radius: var(--sx-r-lg);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  overflow: hidden;
}
.art-compare table { width: 100%; border-collapse: collapse; font-size: 13px; }
.art-compare th, .art-compare td {
  padding: 14px 18px;
  text-align: left;
  border-bottom: 1px solid var(--sx-line);
  vertical-align: top;
}
.art-compare tr:last-child th, .art-compare tr:last-child td { border-bottom: 0; }
.art-compare thead th {
  background: var(--sx-surface-2);
  font-size: 11px; letter-spacing: 0.10em; text-transform: uppercase;
  color: var(--sx-text-3); font-weight: 600;
}
.art-compare tbody th {
  font-weight: 500; color: var(--sx-text-2);
  font-size: 12px; letter-spacing: 0.04em; text-transform: uppercase;
  background: var(--sx-bg);
  width: 180px;
}
.art-compare td { color: var(--sx-text-2); }
.art-compare td b { color: var(--sx-text); font-weight: 600; }
.art-compare .col-h {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 13px; font-weight: 600; color: var(--sx-text);
}
.art-compare .col-h .swatch { width: 8px; height: 8px; border-radius: 2px; background: currentColor; }

/* Inline diagram block */
.art-diagram {
  margin: 32px auto;
  padding: 28px;
  max-width: 1136px;
  border-radius: var(--sx-r-lg);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  position: relative;
  overflow: hidden;
}
.art-diagram-caption {
  margin-top: 14px;
  font-family: var(--sx-font-mono); font-size: 11px;
  color: var(--sx-text-3); letter-spacing: 0.06em;
  display: flex; align-items: center; gap: 8px;
}
.art-diagram-caption .lab {
  color: var(--art-accent); font-weight: 600;
  padding: 2px 6px; border-radius: 4px;
  background: var(--art-accent-tint);
}

/* Listing breakdown cards */
.art-breakdown {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px;
  margin: 32px 0;
}
.art-breakdown-card {
  padding: 20px;
  border-radius: var(--sx-r-md);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  display: flex; flex-direction: column; gap: 10px;
}
.art-breakdown-card .h {
  display: flex; align-items: baseline; justify-content: space-between; gap: 10px;
}
.art-breakdown-card .h .name {
  font-size: 14px; font-weight: 600; color: var(--sx-text); letter-spacing: -0.005em;
}
.art-breakdown-card .h .price {
  font-family: var(--sx-font-num); font-size: 18px; font-weight: 600;
  color: var(--art-accent); letter-spacing: -0.02em;
}
.art-breakdown-card .type {
  font-family: var(--sx-font-mono); font-size: 10px;
  letter-spacing: 0.10em; text-transform: uppercase; color: var(--sx-text-3);
}
.art-breakdown-card .desc { font-size: 13px; color: var(--sx-text-2); line-height: 1.55; }
.art-breakdown-card .metrics {
  margin-top: auto; padding-top: 10px;
  border-top: 1px dashed var(--sx-line);
  display: grid; grid-template-columns: 1fr 1fr; gap: 8px;
  font-family: var(--sx-font-mono); font-size: 10px; color: var(--sx-text-3); letter-spacing: 0.04em;
}
.art-breakdown-card .metrics b { color: var(--sx-text); font-family: var(--sx-font-num); font-weight: 600; font-size: 14px; letter-spacing: -0.01em; display: block; }

/* Callout box */
.art-callout {
  margin: 28px 0;
  padding: 18px 22px;
  display: grid; grid-template-columns: 28px 1fr; gap: 14px;
  border-radius: var(--sx-r-md);
  background: var(--art-accent-tint);
  box-shadow: 0 0 0 1px color-mix(in oklab, var(--art-accent) 35%, transparent) inset;
}
.art-callout .icon {
  width: 28px; height: 28px; border-radius: 50%;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--art-accent); color: #fff;
}
.art-callout .icon svg { width: 14px; height: 14px; }
.art-callout .body { font-size: 14px; color: var(--sx-text); line-height: 1.6; }
.art-callout .body b { color: var(--sx-text); font-weight: 600; }
.art-callout .label {
  font-family: var(--sx-font-mono); font-size: 10px;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--art-accent); font-weight: 600;
  display: block; margin-bottom: 4px;
}

/* § 0X numbered section heads (bb-section-head with class art-numbered) */
.bb-section-head.art-numbered .hnum {
  display: inline-block;
  font-family: var(--sx-font-mono); font-size: 11px;
  color: var(--art-accent); letter-spacing: 0.10em; font-weight: 600;
  margin-bottom: 6px;
}

/* End-of-article rail */
.art-end {
  margin-top: 64px; padding-top: 32px;
  border-top: 1px solid var(--sx-line);
  max-width: 760px; margin-left: auto; margin-right: auto;
}
.art-end-actions {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-bottom: 32px;
}
.art-end-actions .push { margin-left: auto; }
.art-author-bio {
  padding: 24px;
  border-radius: var(--sx-r-md);
  background: var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  display: grid; grid-template-columns: 56px 1fr; gap: 20px; align-items: start;
}
.art-author-bio .av {
  width: 56px; height: 56px; border-radius: 50%;
  background: linear-gradient(135deg, #3D4DFF, #1A1F6B);
  display: inline-flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 600; font-size: 20px;
}
.art-author-bio .lab {
  font-family: var(--sx-font-mono); font-size: 10px;
  letter-spacing: 0.14em; text-transform: uppercase; color: var(--sx-text-3); font-weight: 600;
}
.art-author-bio .name { font-size: 17px; font-weight: 600; color: var(--sx-text); margin-top: 2px; }
.art-author-bio .role { font-size: 13px; color: var(--sx-text-2); margin-top: 2px; }
.art-author-bio .bio { font-size: 13px; color: var(--sx-text-2); margin-top: 10px; line-height: 1.55; max-width: 56ch; }
.art-author-bio .links { display: flex; gap: 6px; margin-top: 12px; flex-wrap: wrap; }
.art-author-bio .links a {
  height: 28px; padding: 0 10px; border-radius: 6px;
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 12px; color: var(--sx-text-2);
  background: var(--sx-bg); box-shadow: 0 0 0 1px var(--sx-line) inset;
}
.art-author-bio .links a:hover { color: var(--sx-text); box-shadow: 0 0 0 1px var(--sx-line-2) inset; }

/* Related */
.art-related {
  margin-top: 56px;
  padding-top: 32px;
  border-top: 1px solid var(--sx-line);
  max-width: 760px; margin-left: auto; margin-right: auto;
}
.art-related h3 {
  font-size: 24px; font-weight: 600; letter-spacing: -0.02em; margin-bottom: 18px;
}
.art-related-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.art-related-card {
  padding: 18px;
  background: var(--sx-surface);
  border-radius: var(--sx-r-md);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  display: flex; flex-direction: column; gap: 10px;
  transition: box-shadow 120ms, transform 120ms;
}
.art-related-card:hover { box-shadow: 0 0 0 1px var(--sx-line-2) inset; transform: translateY(-1px); }
.art-related-card .cat {
  display: inline-flex; align-items: center; gap: 6px;
  font-family: var(--sx-font-mono); font-size: 10px; font-weight: 600;
  letter-spacing: 0.12em; text-transform: uppercase;
}
.art-related-card .cat .dot { width: 8px; height: 8px; border-radius: 2px; background: currentColor; }
.art-related-card h4 { font-size: 15px; font-weight: 600; color: var(--sx-text); line-height: 1.3; letter-spacing: -0.005em; }
.art-related-card .summary { font-size: 13px; color: var(--sx-text-2); line-height: 1.5; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.art-related-card .meta {
  margin-top: auto; padding-top: 6px;
  font-family: var(--sx-font-mono); font-size: 10px; color: var(--sx-text-3); letter-spacing: 0.04em;
}

/* Newsletter strip */
.art-news {
  margin-top: 56px;
  padding: 36px 32px;
  border-radius: var(--sx-r-xl);
  background:
    radial-gradient(500px 220px at 100% 0%, var(--art-accent-tint), transparent 60%),
    var(--sx-surface);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
  display: grid; grid-template-columns: 1.2fr 1fr; gap: 24px; align-items: center;
  max-width: 1136px; margin-left: auto; margin-right: auto;
}
.art-news h3 { font-size: 22px; font-weight: 600; letter-spacing: -0.02em; }
.art-news p { color: var(--sx-text-2); margin-top: 8px; font-size: 13px; line-height: 1.55; max-width: 50ch; }
.art-news-form {
  display: grid; grid-template-columns: 1fr auto; gap: 6px;
  background: var(--sx-bg);
  padding: 6px;
  border-radius: var(--sx-r-md);
  box-shadow: 0 0 0 1px var(--sx-line) inset;
}
.art-news-form input {
  height: 36px; padding: 0 12px; border: 0; outline: none;
  background: transparent; color: var(--sx-text); font-family: inherit; font-size: 13px;
}
.art-news-form input::placeholder { color: var(--sx-text-3); }

/* Building-blocks-specific tweaks under the article template */
.bb-section--first { padding-top: 0; margin-top: 16px; }
.bb-section--first + .bb-section { margin-top: 56px; }
#car-diagram .bb-car { aspect-ratio: auto; height: 460px; }

@media (max-width: 980px) {
  .art-shell { grid-template-columns: 1fr; gap: 32px; }
  .art-aside { position: static; }
  .art-title { font-size: 38px; }
  .art-breakdown { grid-template-columns: 1fr; }
  .art-related-grid { grid-template-columns: 1fr; }
  .art-news { grid-template-columns: 1fr; }
}
@media (max-width: 760px) {
  #car-diagram .bb-car { height: 340px; }
}