/* ============================================================
   ROBIOS LEARN — hub (learn.html) + single article (article.html)
   Tokens only (css/tokens.css). Shared chrome from css/base.css.
   Markdown body styles come from css/cms.css (.md-body).
   Every class here is prefixed learn- / article-.
   ============================================================ */

.learn-body { padding-bottom: 56px; }
.learn-nav-label { color: var(--text-muted); font-weight: 500; font-size: 13px; }

/* ------------------------------ hero ------------------------------ */

.learn-hero { padding-block: 28px 16px; }
.learn-hero h1 {
  font-family: var(--font-display);
  font-size: 34px;
  font-weight: 700;
  line-height: 1.05;
  text-transform: uppercase;
  letter-spacing: var(--ls-display);
  color: var(--text-primary);
}
.learn-sub {
  margin-top: 8px;
  max-width: 62ch;
  font-size: 15px;
  line-height: 22px;
  color: var(--text-secondary);
}

.learn-tabs {
  display: inline-flex;
  gap: 4px;
  margin-top: 16px;
  padding: 4px;
  border-radius: var(--radius-pill);
  background: var(--bg-white-5);
}
.learn-tabs .pill { cursor: pointer; }
.learn-tabs .pill:focus-visible { outline: none; box-shadow: var(--ring-accent); }
.learn-tab-count {
  font-family: var(--font-mono);
  font-size: 11px;
  opacity: .7;
}

/* ---------------------------- toolbar ---------------------------- */

.learn-toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.learn-search {
  position: relative;
  flex: 0 1 300px;
  min-width: 200px;
}
.learn-search svg {
  position: absolute;
  left: 11px;
  top: 50%;
  width: 14px;
  height: 14px;
  transform: translateY(-50%);
  color: var(--text-faint);
  pointer-events: none;
}
.learn-search input {
  width: 100%;
  height: 36px;
  padding: 0 12px 0 32px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-btn);
  background: var(--bg-card);
  font-size: 14px;
  color: var(--text-primary);
  transition: border-color var(--dur-fast) var(--ease-ui), background-color var(--dur-fast) var(--ease-ui);
}
.learn-search input::placeholder { color: var(--text-faint); }
.learn-search input:hover { background: var(--bg-elevated); }
.learn-search input:focus { outline: none; border-color: var(--accent-24); background: var(--bg-elevated); }
.learn-search input:focus-visible { box-shadow: var(--ring-accent); }

.learn-count {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: var(--fs-meta);
  color: var(--text-faint);
  white-space: nowrap;
}

.learn-tags {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}
.learn-tags[hidden] { display: none; }
.learn-tag {
  height: 28px;
  padding: 3px 10px;
  font-family: var(--font-mono);
  cursor: pointer;
}
.learn-tag:focus-visible { outline: none; box-shadow: var(--ring-accent); }

/* ------------------------------ grid ------------------------------ */

.learn-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.learn-card {
  --learn-hue: 78;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 10px;
  border-radius: var(--radius-card-lg);
  background: var(--bg-card);
  box-shadow: var(--inset-highlight);
  color: inherit;
  transition: transform var(--dur-med) var(--ease-pop),
              background-color var(--dur-fast) var(--ease-ui);
}
.learn-card:hover { transform: translateY(-3px); background: var(--bg-elevated); }
.learn-card:focus-visible { outline: none; box-shadow: var(--ring-accent), var(--inset-highlight); }

/* cover — real image, or a generated art block (never a grey box) */
.learn-cover {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  border-radius: var(--radius-card);
  background:
    radial-gradient(120% 120% at 78% 10%, hsl(var(--learn-hue) 72% 24% / .6) 0%, transparent 62%),
    linear-gradient(150deg, #23262A 0%, #14161A 100%);
  box-shadow: var(--inset-highlight);
  display: grid;
  place-items: center;
}
.learn-cover::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--card-glass-sheen);
  pointer-events: none;
}
.learn-cover img,
.learn-cover video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--dur-slow) var(--ease-glide);
}
.learn-card:hover .learn-cover img,
.learn-card:hover .learn-cover video { transform: scale(1.04); }

.learn-art {
  position: relative;
  display: grid;
  place-items: center;
  width: 100%;
  height: 100%;
}
.learn-art::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(90deg, hsl(var(--learn-hue) 80% 60% / .10) 0 1px, transparent 1px 22px),
    repeating-linear-gradient(0deg, hsl(var(--learn-hue) 80% 60% / .08) 0 1px, transparent 1px 22px);
  mask-image: radial-gradient(70% 70% at 50% 45%, #000 10%, transparent 78%);
  -webkit-mask-image: radial-gradient(70% 70% at 50% 45%, #000 10%, transparent 78%);
}
.learn-art-motif {
  position: relative;
  width: 34%;
  max-width: 84px;
  color: hsl(var(--learn-hue) 85% 62% / .55);
  transition: transform var(--dur-slow) var(--ease-glide), color var(--dur-fast) var(--ease-ui);
}
.learn-card:hover .learn-art-motif { transform: scale(1.07); color: hsl(var(--learn-hue) 90% 66% / .8); }

.learn-kind {
  position: absolute;
  top: 8px;
  left: 8px;
  z-index: 2;
  padding: 3px 7px;
  border-radius: var(--radius-badge);
  background: var(--accent-20);
  color: var(--accent);
  font-size: var(--fs-badge);
  font-weight: var(--fw-badge);
  letter-spacing: .04em;
  text-transform: uppercase;
}
.learn-pin {
  position: absolute;
  top: 8px;
  right: 8px;
  z-index: 2;
  display: grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: var(--radius-badge);
  background: var(--accent);
  color: var(--accent-text-on);
}
.learn-pin svg { width: 12px; height: 12px; }

.learn-card-body { display: flex; flex-direction: column; gap: 6px; padding: 0 2px 2px; }
.learn-title {
  font-family: var(--font-display);
  font-size: var(--fs-card-title);
  font-weight: var(--fw-card-title);
  line-height: 1.25;
  letter-spacing: var(--ls-display);
  color: var(--text-primary);
}
.learn-card:hover .learn-title { color: var(--accent); }
.learn-sum {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  font-size: 13px;
  line-height: 19px;
  color: var(--text-secondary);
}
.learn-tagrow { display: flex; flex-wrap: wrap; gap: 4px; }
.learn-tagchip {
  padding: 2px 7px;
  border-radius: var(--radius-pill);
  background: var(--bg-white-5);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-muted);
}
.learn-meta {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-top: 2px;
  font-size: var(--fs-meta);
  color: var(--text-faint);
}
.learn-dot { opacity: .5; }

/* compact variant — the "More in …" strip on article.html */
.learn-card--mini { gap: 8px; padding: 8px; }
.learn-card--mini .learn-sum,
.learn-card--mini .learn-tagrow { display: none; }
.learn-card--mini .learn-title { font-size: 14px; }
.learn-card--mini .learn-art-motif { width: 28%; max-width: 64px; }

/* --------------------------- skeletons --------------------------- */

.learn-skel { pointer-events: none; }
.learn-skel-cover,
.learn-skel-line {
  border-radius: var(--radius-card);
  background: linear-gradient(90deg, var(--bg-elevated) 0%, #2E3238 50%, var(--bg-elevated) 100%);
  background-size: 200% 100%;
  animation: learn-shimmer 1.3s linear infinite;
}
.learn-skel-cover { aspect-ratio: 16 / 9; }
.learn-skel-line { height: 10px; border-radius: var(--radius-badge); }
.learn-skel-line.w70 { width: 70%; }
.learn-skel-line.w45 { width: 45%; }
@keyframes learn-shimmer {
  from { background-position: 200% 0; }
  to   { background-position: -200% 0; }
}

/* -------------------------- empty state -------------------------- */

.learn-empty {
  grid-column: 1 / -1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 48px 20px;
  border-radius: var(--radius-card-lg);
  background: var(--bg-card);
  box-shadow: var(--inset-highlight);
  text-align: center;
}
.learn-empty-icon { width: 40px; height: 40px; color: var(--accent); opacity: .7; }
.learn-empty h3 {
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: var(--ls-display);
  color: var(--text-primary);
}
.learn-empty p {
  max-width: 46ch;
  font-size: 13px;
  line-height: 20px;
  color: var(--text-secondary);
}
.learn-empty a { color: var(--accent); }
.learn-empty a:hover { text-decoration: underline; }
.learn-empty-actions { display: flex; gap: 8px; margin-top: 6px; }

/* ============================================================
   ARTICLE
   ============================================================ */

.article-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 272px;
  gap: 28px;
  align-items: start;
  padding-block: 22px 40px;
}

.article-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-muted);
  transition: color var(--dur-fast) var(--ease-ui);
}
.article-back:hover { color: var(--accent); }
.article-back svg { width: 14px; height: 14px; }

.article-metarow {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin: 16px 0 10px;
  font-size: var(--fs-meta);
  color: var(--text-faint);
}
.article-kind {
  padding: 3px 8px;
  border-radius: var(--radius-badge);
  background: var(--accent-20);
  color: var(--accent);
  font-size: var(--fs-badge);
  font-weight: var(--fw-badge);
  letter-spacing: .04em;
  text-transform: uppercase;
}

.article-title {
  font-family: var(--font-display);
  font-size: 36px;
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: var(--ls-display);
  color: var(--text-primary);
}
.article-lede {
  margin-top: 12px;
  max-width: 72ch;
  font-size: 16px;
  line-height: 25px;
  color: var(--text-secondary);
}

.article-cover {
  margin-top: 20px;
  overflow: hidden;
  border-radius: var(--radius-card-lg);
  box-shadow: var(--inset-highlight);
}
.article-cover .learn-cover { aspect-ratio: 21 / 8; max-height: 440px; border-radius: var(--radius-card-lg); }
.article-cover .learn-art-motif { width: 16%; max-width: 96px; }

.article-body { margin-top: 22px; max-width: 74ch; }
.article-body h2, .article-body h3 { scroll-margin-top: calc(var(--nav-h) + 24px); }

.article-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 22px; }

.article-share {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px solid var(--bg-white-5);
}
.article-share-label {
  font-family: var(--font-mono);
  font-size: var(--fs-meta);
  color: var(--text-faint);
}
.article-copy svg { width: 14px; height: 14px; }

/* ------------------------- side panels ------------------------- */

.article-side {
  position: sticky;
  top: calc(var(--nav-h) + 16px);
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.article-panel {
  padding: 12px;
  border-radius: var(--radius-card);
  background: var(--bg-card);
  box-shadow: var(--inset-highlight);
}
.article-panel[hidden] { display: none; }
.article-panel-h {
  margin-bottom: 8px;
  font-family: var(--font-display);
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--text-faint);
}

.article-toc { display: flex; flex-direction: column; gap: 1px; max-height: 46vh; overflow-y: auto; }
.article-toc a {
  display: block;
  padding: 5px 8px;
  border-left: 2px solid transparent;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 13px;
  line-height: 18px;
  color: var(--text-muted);
  transition: color var(--dur-fast) var(--ease-ui), background-color var(--dur-fast) var(--ease-ui);
}
.article-toc a:hover { color: var(--text-primary); background: var(--bg-white-5); }
.article-toc a.active { color: var(--accent); border-left-color: var(--accent); background: var(--accent-05); }
.article-toc a.lvl3 { padding-left: 18px; font-size: 12px; }

.article-links a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 10px;
  margin-bottom: 6px;
  border-radius: var(--radius-sm);
  background: var(--bg-white-5);
  font-size: 13px;
  color: var(--text-primary);
  transition: background-color var(--dur-fast) var(--ease-ui), color var(--dur-fast) var(--ease-ui);
}
.article-links a:last-child { margin-bottom: 0; }
.article-links a:hover { background: var(--bg-white-10); color: var(--accent); }
.article-links span {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.article-links svg { flex: none; width: 13px; height: 13px; opacity: .6; }

/* --------------------------- more strip --------------------------- */

.article-more { padding-block: 8px 40px; }
.article-more[hidden] { display: none; }
.article-more-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

/* ------------------------ loading / 404 ------------------------ */

.article-loading { padding-block: 32px; display: flex; flex-direction: column; gap: 12px; max-width: 74ch; }
/* the [hidden] attr must beat the display:flex above (equal specificity → later wins) */
.article-loading[hidden] { display: none; }
.article-loading .learn-skel-line { height: 14px; }
.article-loading .learn-skel-line.tall { height: 34px; }

.article-fail {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  max-width: 520px;
  margin: 48px auto;
  padding: 44px 24px;
  border-radius: var(--radius-card-lg);
  background: var(--bg-card);
  box-shadow: var(--inset-highlight);
  text-align: center;
}
.article-fail-icon { width: 40px; height: 40px; color: var(--accent); opacity: .7; }
.article-fail h1 {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: var(--ls-display);
}
.article-fail p { max-width: 44ch; font-size: 14px; line-height: 21px; color: var(--text-secondary); }
.article-fail-actions { display: flex; gap: 8px; margin-top: 6px; }

/* ---------------------------- responsive ---------------------------- */

@media (max-width: 1100px) {
  .learn-grid,
  .article-more-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .article-shell { grid-template-columns: minmax(0, 1fr); gap: 20px; }
  .article-side { position: static; flex-direction: row; flex-wrap: wrap; }
  .article-side .article-panel { flex: 1 1 260px; }
  .article-toc { max-height: none; }
}

@media (max-width: 760px) {
  .learn-grid,
  .article-more-grid { grid-template-columns: minmax(0, 1fr); }
  .learn-hero h1 { font-size: 26px; }
  .learn-search { flex: 1 1 100%; }
  .learn-count { margin-left: 0; }
  .article-title { font-size: 26px; }
  .article-lede { font-size: 15px; line-height: 23px; }
  .article-cover .learn-cover { aspect-ratio: 16 / 9; }
  .article-cover .learn-art-motif { width: 30%; }
}

@media (prefers-reduced-motion: reduce) {
  .learn-card,
  .learn-cover img,
  .learn-art-motif { transition: none !important; }
  .learn-card:hover { transform: none; }
  .learn-card:hover .learn-cover img,
  .learn-card:hover .learn-art-motif { transform: none; }
  .learn-skel-cover,
  .learn-skel-line { animation: none; }
}