.vertical-hero {
  background-color: var(--ink);
  color: var(--paper);
  padding-block: var(--space-l);
  border-bottom: 2px solid var(--red);
}
.vertical-hero__inner {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-m);
}
@media (min-width: 800px) {
  .vertical-hero__inner {
    grid-template-columns: 1fr auto;
    align-items: end;
    gap: var(--space-xl);
  }
}
.vertical-hero__kicker {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--red);
  display: block;
  margin-bottom: var(--space-xs);
}
.vertical-hero__title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.05;
  color: var(--paper);
  margin-bottom: var(--space-s);
}
.vertical-hero__desc {
  font-size: 0.95rem;
  line-height: 1.65;
  color: rgba(247,244,238,0.65);
  max-width: 56ch;
  margin-bottom: 0;
}
.vertical-hero__stat {
  text-align: right;
  flex-shrink: 0;
}
.vertical-hero__stat-value {
  font-family: var(--font-display);
  font-size: clamp(2.8rem, 6vw, 4rem);
  font-weight: 900;
  color: var(--paper);
  line-height: 1;
  display: block;
}
.vertical-hero__stat-label {
  font-family: var(--font-mono);
  font-size: 0.58rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: rgba(247,244,238,0.35);
  display: block;
  margin-top: 0.25rem;
}

/* ── PAGE BODY ── */
.concepts-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  align-items: start;
  padding-block: var(--space-xl);
}
@media (min-width: 1000px) {
  .concepts-layout { grid-template-columns: 1fr 220px; }
}

/* ── CONCEPT GRID ──
   The signature structure of this page.
   Each concept is a card built around its
   Chinese character — the glyph does the
   visual work, text provides the scaffold. */
.concept-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  border: 1px solid var(--rule);
  border-top: 3px solid var(--ink);
}
@media (min-width: 600px) {
  .concept-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 900px) {
  .concept-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ── CONCEPT CARD ── */
.concept-card {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 0;
  border-bottom: 1px solid var(--rule);
  text-decoration: none;
  color: inherit;
  transition: background-color 0.1s ease;
  position: relative;
}
/* Right border for left-column cards */
@media (min-width: 600px) {
  .concept-card:nth-child(odd) {
    border-right: 1px solid var(--rule);
  }
}
/* Remove bottom border from last row */
@media (min-width: 600px) {
  .concept-card:nth-last-child(-n+2) {
    border-bottom: none;
  }
}
@media (max-width: 599px) {
  .concept-card:last-child { border-bottom: none; }
}

.concept-card:hover {
  background-color: var(--paper-tint);
  text-decoration: none;
}
.concept-card:focus-visible {
  outline: 2px solid var(--red);
  outline-offset: -2px;
}

/* Glyph column */
.concept-card__glyph-col {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: var(--space-m) var(--space-s) var(--space-m) var(--space-m);
  border-right: 1px solid var(--rule);
}
.concept-card__glyph {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 2.8rem);
  line-height: 1;
  color: var(--rule);
  transition: color 0.1s ease;
  /* Intentionally muted — the title carries meaning */
}
.concept-card:hover .concept-card__glyph {
  color: var(--mid);
}

/* Body column */
.concept-card__body {
  padding: var(--space-m) var(--space-m) var(--space-m) var(--space-m);
}
.concept-card__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem;
  margin-bottom: 0.25rem;
}
.concept-card__pinyin {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.1em;
  color: var(--mid);
}
.concept-card__read-time {
  font-family: var(--font-mono);
  font-size: 0.55rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--light);
}
.concept-card__title {
  font-family: var(--font-display);
  font-size: clamp(0.95rem, 2vw, 1.1rem);
  font-weight: 700;
  color: var(--ink);
  line-height: 1.25;
  margin-bottom: 0.4rem;
  display: block;
}
.concept-card:hover .concept-card__title {
  color: var(--red);
}
.concept-card__desc {
  font-size: 0.82rem;
  color: var(--mid);
  line-height: 1.6;
  margin-bottom: var(--space-s);
}
.concept-card__arrow {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.08em;
  color: var(--light);
  display: block;
}
.concept-card:hover .concept-card__arrow {
  color: var(--red);
}

/* ── SECTION LABEL above the grid ── */
.grid-label {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--mid);
  display: block;
  padding-bottom: var(--space-s);
  border-bottom: 1px solid var(--rule);
  margin-bottom: var(--space-m);
}

/* ── LEARNING PATHS CALLOUT ── */
.paths-callout {
  border: 1px solid var(--rule);
  border-top: 3px solid var(--gold);
  padding: var(--space-l);
  background-color: var(--gold-tint);
  margin-top: var(--space-xl);
}
.paths-callout__label {
  font-family: var(--font-mono);
  font-size: 0.58rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--gold);
  display: block;
  margin-bottom: var(--space-s);
}
.paths-callout__title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: var(--space-s);
}
.paths-callout p {
  font-size: 0.9rem;
  color: var(--ink);
  line-height: 1.7;
  margin-bottom: var(--space-m);
}
.paths-callout__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-s);
}
.path-link {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.08em;
  color: var(--link);
  border: 1px solid var(--rule);
  padding: 0.4rem 0.8rem;
  text-decoration: none;
  background-color: var(--paper);
}
.path-link:hover { border-color: var(--ink); color: var(--ink); }

/* ── SIDEBAR — concept index specific ── */
/* Uses .article-sidebar from common.css for sticky behaviour.
   Additional layout for this sidebar only: */
.concepts-sidebar {}

/* Reading order guide */
.reading-order {
  list-style: none;
  padding: 0;
  counter-reset: reading-order;
}
.reading-order__item {
  counter-increment: reading-order;
  display: grid;
  grid-template-columns: 1.4rem 1fr;
  gap: var(--space-xs);
  padding-block: 0.5rem;
  border-bottom: 1px solid var(--rule);
  align-items: start;
  text-decoration: none;
  color: inherit;
}
.reading-order__item:last-child { border-bottom: none; }
.reading-order__item:hover .reading-order__title { color: var(--red); }
.reading-order__num {
  font-family: var(--font-mono);
  font-size: 0.55rem;
  color: var(--light);
  padding-top: 0.2rem;
  text-align: right;
}
.reading-order__num::before { content: counter(reading-order, decimal-leading-zero); }
.reading-order__title {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.04em;
  color: var(--mid);
  line-height: 1.5;
  display: block;
}
.reading-order__pinyin {
  font-family: var(--font-mono);
  font-size: 0.54rem;
  color: var(--light);
  display: block;
}