/* ==========================================================================
   ARTICLE DESIGN SYSTEM — /shop shared article body stylesheet
   --------------------------------------------------------------------------
   One canonical stylesheet for ALL /shop article pages (published and
   factory-generated). Never duplicate per-article <style> blocks: every
   article shell references this file. Generated pages must keep the
   structure contract in docs/ARTICLE-RULES.md:

     <main class="article-main">
       <article class="article">           <- editorial scope (links/words)
         <header class="article-header">    <- breadcrumb / kicker
         <h1 class="article-title">
         <footer class="article-meta">      <- date / author byline
         <nav class="article-toc">          <- only when >= 4 H2 sections
         <div class="article-body">         <- prose (H2 ids: sec-N)
       </article>
       <section class="article-cta">        <- one restrained CTA, never in scope
       <section class="article-related">    <- related cards, never in scope
     </main>

   Brand tokens mirror assets/css/base.css (primary #FF6B00, glass dark
   theme). Light is the default; dark applies via [data-theme="dark"] or
   (for no-JS article pages) prefers-color-scheme.
   ========================================================================== */

/* --- 1. TOKENS ---------------------------------------------------------- */
:root {
  --article-max: 48rem;            /* ~768px prose measure            */
  --article-wide: 64rem;           /* tables/media region (64rem)     */
  --article-padding: clamp(16px, 5vw, 24px);
  --article-line-height: 1.75;
  --article-radius: 14px;
  --article-border: #e3e3e8;
  --article-muted: #6b6b70;
  --article-surface: #ffffff;
  --article-bg: #f2f2f7;
  --article-text: #1c1c1e;
  --article-brand: #ff6b00;
  --article-brand-strong: #cc5500;
  --article-link: #0056d2;
  --article-link-visited: #5b3fc4;
  --article-focus: #0056d2;
  --article-shadow: 0 8px 28px -14px rgba(0, 0, 0, 0.18);
  --article-font: 'Plus Jakarta Sans', system-ui, -apple-system, 'Segoe UI',
    Roboto, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --article-border: #2c2c2e;
    --article-muted: #aeaeb2;
    --article-surface: #1c1c1e;
    --article-bg: #0d0d0f;
    --article-text: #f5f5f7;
    --article-link: #409cff;
    --article-link-visited: #bf5af2;
    --article-focus: #409cff;
    --article-shadow: 0 10px 34px -14px rgba(0, 0, 0, 0.7);
  }
}

[data-theme="dark"] {
  --article-border: #2c2c2e;
  --article-muted: #aeaeb2;
  --article-surface: #1c1c1e;
  --article-bg: #0d0d0f;
  --article-text: #f5f5f7;
  --article-link: #409cff;
  --article-link-visited: #bf5af2;
  --article-focus: #409cff;
  --article-shadow: 0 10px 34px -14px rgba(0, 0, 0, 0.7);
}

/* --- 2. SHELL ----------------------------------------------------------- */
body {
  margin: 0;
  font-family: var(--article-font);
  background: var(--article-bg);
  color: var(--article-text);
  line-height: var(--article-line-height);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  /* FAB stack clearance (chatbot bottom-right) + iOS safe area */
  padding-bottom: calc(88px + env(safe-area-inset-bottom, 0px));
}

.article-main {
  max-width: var(--article-max);
  margin: 0 auto;
  padding: 24px var(--article-padding) 8px;
}

.article {
  background: var(--article-surface);
  border: 1px solid var(--article-border);
  border-radius: var(--article-radius);
  box-shadow: var(--article-shadow);
  padding: clamp(20px, 4.5vw, 40px) clamp(16px, 4.5vw, 44px);
}

@media (min-width: 768px) {
  .article-main { padding-top: 40px; }
  .article { padding: 44px 52px; }
}

/* --- 3. BREADCRUMB ------------------------------------------------------ */
.article-breadcrumb {
  font-size: 0.85rem;
  color: var(--article-muted);
  margin: 0 0 14px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}
.article-breadcrumb a {
  color: var(--article-muted);
  text-decoration: none;
}
.article-breadcrumb a:hover,
.article-breadcrumb a:focus-visible {
  color: var(--article-brand-strong);
  text-decoration: underline;
}
.article-breadcrumb .bc-sep {
  color: var(--article-border);
  user-select: none;
}
.article-breadcrumb [aria-current="page"] {
  color: var(--article-text);
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* --- 4. HEADER / H1 / META ---------------------------------------------- */
.article-kicker {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--article-brand-strong);
  background: color-mix(in srgb, var(--article-brand) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--article-brand) 28%, transparent);
  border-radius: 999px;
  padding: 4px 12px;
  margin: 0 0 14px;
}

.article-title,
.article h1 {
  font-size: clamp(1.55rem, 4.6vw, 2.15rem);
  line-height: 1.25;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--article-text);
  margin: 0 0 12px;
  overflow-wrap: break-word;      /* long Vietnamese H1s wrap naturally */
}

.article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  font-size: 0.85rem;
  color: var(--article-muted);
  margin: 0 0 6px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--article-border);
}
.article-meta time { font-weight: 600; }

/* --- 5. TOC (Mục lục) ---------------------------------------------------- */
.article-toc {
  margin: 20px 0 26px;
  border: 1px solid var(--article-border);
  border-radius: 12px;
  background: color-mix(in srgb, var(--article-muted) 7%, transparent);
}
.article-toc summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 0.95rem;
  padding: 12px 16px;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 8px;
  user-select: none;
  border-radius: 12px;
}
.article-toc summary::-webkit-details-marker { display: none; }
.article-toc summary::before {
  content: "▸";
  display: inline-block;
  color: var(--article-brand-strong);
  transition: transform 0.15s ease;
}
.article-toc[open] summary::before { transform: rotate(90deg); }
.article-toc summary:focus-visible {
  outline: 2px solid var(--article-focus);
  outline-offset: 2px;
}
.article-toc ol {
  margin: 0;
  padding: 2px 16px 14px 40px;
  font-size: 0.95rem;
}
.article-toc li { margin: 7px 0; }
.article-toc a {
  color: var(--article-link);
  text-decoration: none;
}
.article-toc a:hover,
.article-toc a:focus-visible { text-decoration: underline; }

/* --- 6. BODY TYPOGRAPHY -------------------------------------------------- */
.article-body {
  font-size: clamp(1rem, 0.55rem + 0.9vw, 1.125rem);  /* 16 -> 18px */
  line-height: var(--article-line-height);
  color: var(--article-text);
}

.article-body p {
  margin: 0 0 1.15em;
  overflow-wrap: break-word;
}

.article-body h2 {
  font-size: clamp(1.22rem, 2.6vw, 1.45rem);
  line-height: 1.35;
  font-weight: 800;
  margin: 2em 0 0.6em;
  padding-top: 0.35em;
  color: var(--article-text);
  scroll-margin-top: 16px;
}
.article-body h2::before {
  content: "";
  display: block;
  width: 34px;
  height: 4px;
  border-radius: 2px;
  background: var(--article-brand);
  margin-bottom: 10px;
}

.article-body h3 {
  font-size: clamp(1.05rem, 2vw, 1.18rem);
  font-weight: 700;
  margin: 1.6em 0 0.5em;
  color: var(--article-text);
  scroll-margin-top: 16px;
}

.article-body h4 {
  font-size: 1rem;
  font-weight: 700;
  margin: 1.4em 0 0.4em;
  color: var(--article-muted);
}

/* --- 7. LISTS ------------------------------------------------------------ */
.article-body ul,
.article-body ol {
  margin: 0 0 1.15em;
  padding-left: 1.5em;
}
.article-body ul { list-style: disc; }
.article-body ol { list-style: decimal; }
.article-body li {
  margin: 0.45em 0;
  padding-left: 0.25em;
}
.article-body li::marker {
  color: var(--article-brand-strong);
  font-weight: 700;
}
.article-body ul ul,
.article-body ol ol,
.article-body ul ol,
.article-body ol ul {
  margin: 0.45em 0 0.2em;
}
.article-body ul ul { list-style: circle; }

/* --- 8. LINKS ------------------------------------------------------------ */
.article-body a,
.article-desc a {
  color: var(--article-link);
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--article-link) 40%, transparent);
  text-underline-offset: 3px;
}
.article-body a:hover { text-decoration-color: currentColor; }
.article-body a:visited,
.article-desc a:visited { color: var(--article-link-visited); }
.article-body a:focus-visible,
.article a:focus-visible {
  outline: 2px solid var(--article-focus);
  outline-offset: 2px;
  border-radius: 3px;
}

/* --- 9. TABLES — never break the 375px body ------------------------------ */
.article-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin: 1.4em 0 1.6em;
  border: 1px solid var(--article-border);
  border-radius: 10px;
}
.article-body table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;           /* readable, not shrunk to illegibility */
  min-width: 24rem;             /* scroll inside the wrapper instead     */
}
.article-body th,
.article-body td {
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--article-border);
  vertical-align: top;
}
.article-body th {
  background: color-mix(in srgb, var(--article-muted) 10%, transparent);
  font-weight: 700;
  white-space: nowrap;
}
.article-body tbody tr:last-child td { border-bottom: 0; }
.article-body tbody tr:hover td {
  background: color-mix(in srgb, var(--article-brand) 5%, transparent);
}

/* --- 10. BLOCKQUOTE / NOTE / WARNING ------------------------------------- */
.article-body blockquote {
  margin: 1.4em 0;
  padding: 10px 18px;
  border-left: 4px solid var(--article-brand);
  background: color-mix(in srgb, var(--article-brand) 6%, transparent);
  border-radius: 0 10px 10px 0;
  color: var(--article-text);
}
.article-body blockquote p:last-child { margin-bottom: 0; }

.article-body .note,
.article-body .tip,
.article-body .warning {
  margin: 1.4em 0;
  padding: 14px 18px;
  border-radius: 10px;
  border: 1px solid var(--article-border);
  background: color-mix(in srgb, var(--article-muted) 7%, transparent);
}
.article-body .warning {
  border-left: 4px solid #c41c00;
  background: color-mix(in srgb, #c41c00 7%, transparent);
}
.article-body .tip {
  border-left: 4px solid #006837;
  background: color-mix(in srgb, #006837 7%, transparent);
}
.article-body .note,
.article-body .tip,
.article-body .warning { font-size: 0.97em; }
.article-body .note p:last-child,
.article-body .tip p:last-child,
.article-body .warning p:last-child { margin-bottom: 0; }

/* --- 11. IMAGES ----------------------------------------------------------- */
.article-body img {
  max-width: 100%;
  height: auto;
  border-radius: 10px;
}
.article-body figure {
  margin: 1.5em 0;
}
.article-body figcaption {
  font-size: 0.85rem;
  color: var(--article-muted);
  margin-top: 8px;
  text-align: center;
}

/* --- 12. SOURCE SECTION ---------------------------------------------------- */
.article-body h2#nguon-tham-khao + p,
.article-body p.src {
  font-size: 0.88rem;
  color: var(--article-muted);
}

/* --- 13. CTA (one, restrained, outside editorial scope) ------------------- */
.article-cta {
  max-width: var(--article-max);
  margin: 22px auto 6px;
  padding: 0 var(--article-padding);
}
.article-cta-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  border: 1px solid color-mix(in srgb, var(--article-brand) 30%, transparent);
  background: color-mix(in srgb, var(--article-brand) 7%, transparent);
  border-radius: var(--article-radius);
  padding: 18px 22px;
}
.article-cta p {
  margin: 0;
  font-weight: 600;
  font-size: 0.98rem;
  color: var(--article-text);
}
.article-cta a {
  display: inline-block;
  min-height: 44px;
  padding: 10px 22px;
  border-radius: 999px;
  background: var(--article-brand);
  color: #fff;
  font-weight: 700;
  font-size: 0.95rem;
  text-decoration: none;
  white-space: nowrap;
  border: none;
}
.article-cta a:hover { background: var(--article-brand-strong); }
.article-cta a:focus-visible {
  outline: 3px solid var(--article-focus);
  outline-offset: 2px;
}

/* --- 14. RELATED ARTICLES --------------------------------------------------- */
.article-related {
  max-width: var(--article-max);
  margin: 30px auto 0;
  padding: 0 var(--article-padding);
}
.article-related-title,
.article-pn-title {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--article-text);
  margin: 0 0 14px;
}
.article-related-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}
@media (min-width: 640px) { .article-related-list { grid-template-columns: 1fr 1fr; } }
@media (min-width: 1024px) { .article-related-list { grid-template-columns: 1fr 1fr 1fr; } }
.article-related-list a {
  display: block;
  height: 100%;
  padding: 14px 16px;
  border: 1px solid var(--article-border);
  border-radius: 12px;
  background: var(--article-surface);
  text-decoration: none;
  transition: border-color 0.2s ease, transform 0.2s ease;
}
.article-related-list a:hover,
.article-related-list a:focus-visible {
  border-color: var(--article-brand);
  transform: translateY(-2px);
  outline: none;
}
.article-related-list a:focus-visible { box-shadow: 0 0 0 3px color-mix(in srgb, var(--article-focus) 45%, transparent); }
.rel-title {
  display: block;
  font-weight: 700;
  font-size: 0.95rem;
  line-height: 1.45;
  color: var(--article-text);
}
.rel-topic {
  display: block;
  margin-top: 6px;
  font-size: 0.78rem;
  color: var(--article-muted);
}

/* --- 15. PREVIOUS / NEXT ---------------------------------------------------- */
.article-pn {
  max-width: var(--article-max);
  margin: 18px auto 0;
  padding: 0 var(--article-padding);
}
.article-pn-list {
  list-style: none;
  display: flex;
  gap: 12px;
  margin: 0;
  padding: 0;
}
.article-pn-list li { flex: 1 1 0; min-width: 0; }
.article-pn-list a {
  display: block;
  padding: 12px 16px;
  border: 1px solid var(--article-border);
  border-radius: 10px;
  background: var(--article-surface);
  text-decoration: none;
  font-size: 0.88rem;
  color: var(--article-text);
}
.article-pn-list a:hover,
.article-pn-list a:focus-visible { border-color: var(--article-brand); }
.article-pn-list .pn-label {
  display: block;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--article-muted);
  margin-bottom: 4px;
}
.article-pn-list .pn-next { text-align: right; }

/* --- 16. FOOTER TRANSITION --------------------------------------------------- */
main.article-main + .site-footer-compact {
  border-top: 1px solid var(--article-border);
}

/* --- 17. REDUCED MOTION ------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  .article-related-list a,
  .article-toc summary::before,
  .article-cta a { transition: none; transform: none; }
}

/* --- 18. WIDE CONTENT ESCAPE HATCH -------------------------------------------- */
/* Tables or media that genuinely need > 48rem sit in .article-wide-block
   and are allowed to span up to --article-wide, still centered. */
.article-wide-block {
  max-width: var(--article-wide);
  margin-left: calc(50% - min(var(--article-wide), 100%) / 2);
}