/* ============================================================
   blog-page.css — blog listing and static article details
   Own classes use the bp- prefix. Unprefixed selectors here
   (.card*, .posts-grid, .empty-state, .post-header, .post-body)
   target markup rendered by main.js per the SPEC contract.
   All colors come from base.css design tokens — never hardcoded.
   ============================================================ */

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

.bp-hero {
  padding: clamp(64px, 8vw, 112px) 0 clamp(30px, 4vw, 44px);
}

.bp-kicker {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 24px;
  margin-bottom: 22px;
}

.bp-title {
  font-size: clamp(40px, 6vw, 78px);
  max-width: 20ch;
}

/* yellow highlight mark (SPEC: dark ink on --accent fill, never
   yellow text on --bg). inline-block: an inline span's background
   overflows the tight 1.05 line box and clips the previous line's
   glyphs; copy is split into two <em>s so it still wraps on mobile. */
.bp-title em {
  display: inline-block;
  font-style: normal;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 0 0.12em;
}

.bp-sub {
  max-width: 62ch;
  margin: 22px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-dim);
}

/* ---------- filter pills (decorative; mirror the DB categories) ---------- */

.bp-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: clamp(28px, 4vw, 42px);
}

.bp-filter {
  font-family: var(--font-mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-dim);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 18px;
  transition: transform 0.2s var(--ease-out-quart), color 0.2s ease,
    border-color 0.2s ease, background-color 0.2s ease;
}
.bp-filter:hover {
  transform: translateY(-2px);
  border-color: var(--ink);
  color: var(--ink);
}
.bp-filter--active {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
}
.bp-filter--active:hover {
  border-color: var(--accent);
  color: var(--accent-ink);
}

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

.bp-list {
  padding: clamp(34px, 4.5vw, 54px) 0 clamp(72px, 9vw, 120px);
}

.posts-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(28px, 3.5vw, 44px) clamp(24px, 2.5vw, 36px);
}

/* ---------- cards (rendered by main.js, SPEC contract) ----------
   Editorial card: flat 1px --line frame, no shadow. The thumb scene
   lives on .card-thumb::after so hover can zoom the artwork only. */

.card {
  display: flex;
  border: 1px solid var(--line);
  background: var(--bg);
  transition: transform 0.3s var(--ease-out-quart), border-color 0.25s ease;
}
.card:hover,
.card:focus-within {
  transform: translateY(-4px);
  border-color: var(--ink);
}

.card-link {
  display: flex;
  flex-direction: column;
  width: 100%;
}

/* thumbnail: pure-CSS artwork, aspect 16/10, distinct scene per category */
.card-thumb {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
  margin-bottom: 18px;
  background: var(--bg-alt);
}

/* the paintable scene (zooms subtly on hover) */
.card-thumb::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  background:
    radial-gradient(70% 90% at 82% 12%, color-mix(in srgb, var(--blue) 38%, transparent), transparent 62%),
    radial-gradient(60% 80% at 12% 88%, color-mix(in srgb, var(--accent) 30%, transparent), transparent 58%);
  transition: transform 0.6s var(--ease-out-quint);
}
.card-link:hover .card-thumb::after,
.card:focus-within .card-thumb::after {
  transform: scale(1.045);
}

/* subtle scanline texture over every thumb */
.card-thumb::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  background: repeating-linear-gradient(
    to bottom,
    transparent 0 3px,
    color-mix(in srgb, var(--bg) 32%, transparent) 3px 4px
  );
  opacity: 0.55;
  pointer-events: none;
}

/* category scenes — keyed off the six DB categories (case-insensitive) */

/* SEO — sunrise over paper */
.card-thumb[data-cat="SEO" i]::after {
  background:
    radial-gradient(85% 110% at 20% 10%, color-mix(in srgb, var(--accent) 85%, transparent) 0%, transparent 55%),
    linear-gradient(150deg, var(--bg-alt), var(--bg));
}
/* AI Overviews — blue beam */
.card-thumb[data-cat="AI Overviews" i]::after {
  background:
    linear-gradient(115deg, var(--blue) 0%, transparent 62%),
    radial-gradient(70% 90% at 85% 92%, color-mix(in srgb, var(--blue) 45%, transparent), transparent 60%);
}
/* Content Strategy — blue column, yellow flare */
.card-thumb[data-cat="Content Strategy" i]::after {
  background:
    radial-gradient(60% 85% at 88% 16%, color-mix(in srgb, var(--accent) 62%, transparent), transparent 55%),
    linear-gradient(100deg, var(--blue) 0%, var(--bg-alt) 60%);
}
/* Generative AI — conic swirl */
.card-thumb[data-cat="Generative AI" i]::after {
  background:
    conic-gradient(from 210deg at 62% 42%, var(--bg) 0deg, var(--blue) 110deg, var(--bg) 225deg, var(--bg-alt) 360deg);
}
/* 生成式引擎优化 — 精密网格 */
.card-thumb[data-cat="Generative Engine Optimization" i]::after {
  background:
    radial-gradient(75% 100% at 10% 92%, color-mix(in srgb, var(--accent) 55%, transparent), transparent 58%),
    repeating-linear-gradient(90deg, var(--line) 0 1px, transparent 1px 56px),
    repeating-linear-gradient(0deg, var(--line) 0 1px, transparent 1px 56px);
}
/* Measurement — ledger rules + signal blobs */
.card-thumb[data-cat="Measurement" i]::after {
  background:
    radial-gradient(70% 95% at 82% 88%, color-mix(in srgb, var(--accent) 50%, transparent), transparent 58%),
    radial-gradient(65% 85% at 14% 12%, color-mix(in srgb, var(--blue) 42%, transparent), transparent 60%),
    repeating-linear-gradient(0deg, var(--line) 0 1px, transparent 1px 22px);
}

/* mono category chip — dark plaque + yellow text (readable both themes) */
.card-cat {
  position: absolute;
  left: 14px;
  bottom: 12px;
  z-index: 2;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--accent);
  background: var(--band-dark-bg);
  border: 1px solid var(--band-dark-line);
  padding: 4px 10px;
}

/* ---------- card meta ---------- */

.card-meta {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 14px;
  padding: 0 20px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-bottom: 10px;
}
.card-tags {
  color: var(--tag-ink);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  text-align: right;
}

.card-title {
  padding: 0 20px;
  font-size: clamp(20px, 1.8vw, 24px);
  font-weight: 500;
  line-height: 1.18;
  transition: color 0.2s ease;
}
.card-link:hover .card-title,
.card:focus-within .card-title {
  color: var(--link-ink);
}

.card-excerpt {
  margin: 12px 0 22px; /* bottom space as margin: vertical padding on a
                          line-clamped box lets the next line bleed through */
  padding: 0 20px;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--ink-dim);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ---------- empty state (API down / no posts) ---------- */

.empty-state {
  grid-column: 1 / -1;
  border: 1px dashed var(--line);
  padding: clamp(40px, 6vw, 72px) 24px;
  text-align: center;
  font-family: var(--font-mono);
  color: var(--muted);
  font-size: 14px;
  letter-spacing: 0.04em;
}
.empty-state::before {
  content: "//.status";
  display: block;
  color: var(--tag-ink);
  font-size: 12px;
  letter-spacing: 0.08em;
  margin-bottom: 10px;
}

/* ---------- post detail ---------- */

.bp-post {
  padding: clamp(56px, 7vw, 96px) 0 clamp(72px, 9vw, 120px);
}

.bp-post-col {
  max-width: 800px;
  margin: 0 auto;
}

/* back-to-blog mono link */
.bp-back {
  display: inline-block;
  font-size: 12.5px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin-bottom: clamp(30px, 4vw, 48px);
  transition: color 0.2s ease;
}
.bp-back::before {
  content: "\2190\0020"; /* ← */
  display: inline-block;
  color: var(--tag-ink);
  transition: transform 0.2s var(--ease-out-quart);
}
.bp-back:hover { color: var(--link-ink); }
.bp-back:hover::before { transform: translateX(-3px); }

/* detail header rendered by main.js:
   .post-header > .post-meta(.tag + time) + .post-title + .post-author */
.post-header .post-meta {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 6px 14px;
  margin: 0 0 18px;
}
.post-header .post-meta time {
  color: var(--muted);
  font-size: 12.5px;
  letter-spacing: 0.06em;
}
.post-header .post-title {
  font-size: clamp(34px, 4.6vw, 56px);
  margin-bottom: 18px;
}
.post-header .post-author {
  margin: 0;
  color: var(--ink-dim);
  font-size: 13px;
  letter-spacing: 0.04em;
}

/* ---------- post body typography ---------- */

.post-body {
  max-width: 68ch;
  margin-top: clamp(28px, 4vw, 44px);
  border-top: 1px solid var(--line);
  padding-top: clamp(26px, 3.5vw, 40px);
}

/* lede — the opening paragraph earns a bigger stage */
.post-body > p:first-of-type {
  font-size: 1.13em;
  line-height: 1.7;
  color: var(--ink);
}

.post-body p {
  color: var(--ink-dim);
  line-height: 1.75;
  margin: 0 0 1.2em;
}

.post-body h2,
.post-body h3 {
  margin: 2em 0 0.6em;
}
.post-body h2 {
  font-size: clamp(26px, 3vw, 34px);
  font-weight: 400;
}
.post-body h3 {
  font-size: clamp(21px, 2.4vw, 27px);
  font-weight: 500;
  margin-top: 2.4em; /* extra air above sub-heads */
}

.post-body ul,
.post-body ol {
  color: var(--ink-dim);
  line-height: 1.75;
  margin: 0 0 1.4em;
}
.post-body li { margin-bottom: 0.55em; }
.post-body ul li {
  position: relative;
  padding-left: 1.4em;
}
.post-body ul li::before {
  content: "+";
  position: absolute;
  left: 0.2em;
  color: var(--tag-ink);
  font-weight: 700;
}
.post-body ol {
  list-style: decimal;
  padding-left: 1.4em;
}
.post-body ol li { padding-left: 0.4em; }
.post-body ol li::marker {
  color: var(--tag-ink);
  font-weight: 700;
}

.post-body a {
  color: var(--link-ink);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: color-mix(in srgb, var(--link-ink) 45%, transparent);
  transition: color 0.2s ease, text-decoration-color 0.2s ease;
}
.post-body a:hover {
  text-decoration-color: currentColor;
}
.post-body strong { color: var(--ink); }

/* pull quote — framed by rules, no left color bar */
.post-body blockquote {
  margin: 2em 0;
  padding: clamp(18px, 2.5vw, 26px) 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  color: var(--ink);
  font-style: italic;
}
.post-body blockquote::before {
  content: "//.";
  display: block;
  color: var(--tag-ink);
  font-style: normal;
  font-size: 12px;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
}
.post-body blockquote p {
  margin: 0;
  color: var(--ink);
}

.post-body code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  color: var(--tag-ink);
  /* --bg chip (not --bg-alt): --tag-ink on --bg-alt is 4.28:1 in the light
     theme, just under AA; on --bg it clears 4.5:1. Border keeps the chip shape. */
  background: var(--bg);
  border: 1px solid var(--line);
  padding: 1px 6px;
}
.post-body hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 2.5em 0;
}

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

@media (max-width: 1024px) {
  .posts-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .posts-grid { grid-template-columns: 1fr; }
  .bp-kicker .pluses { display: none; }
  .bp-title { max-width: none; }
  .bp-filters { gap: 8px; }
  .bp-filter { padding: 7px 14px; }
  .card-meta {
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
  }
  .card-tags { text-align: left; }
}