.topic-index {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: var(--space-12) var(--container-pad) var(--space-16);
}

/* ── Hero ────────────────────────────────────────────────── */
.topic-index__heading {
  font-family: var(--font-display);
  font-size: clamp(2.25rem, 7vw, 3.75rem);
  font-weight: 500;
  line-height: var(--line-height-tight);
  letter-spacing: -0.03em;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.topic-index__subheading {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  max-width: 50ch;
  line-height: var(--line-height-loose);
  margin-bottom: var(--space-10);
}

/* ── Topic grid ──────────────────────────────────────────── */
.topic-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
  counter-reset: topic-card;
}

@media (min-width: 600px) {
  .topic-list {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-5);
  }
}

/* ── Topic card ──────────────────────────────────────────── */
.topic-card {
  counter-increment: topic-card;
}

.topic-card__link {
  display: flex;
  flex-direction: column;
  min-height: 180px;
  padding: var(--space-6);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  transition: all var(--duration-base) var(--ease-out);
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
}

/* Numbered index in top-right */
.topic-card__link::before {
  content: "0" counter(topic-card);
  position: absolute;
  top: var(--space-5);
  right: var(--space-6);
  font-family: var(--font-display);
  font-size: var(--font-size-sm);
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--color-text-subtle);
}

/* Animated accent bar on hover */
.topic-card__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent) 0%, var(--color-primary) 100%);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--duration-base) var(--ease-out);
}

.topic-card__link:hover {
  box-shadow: var(--shadow-md);
  border-color: transparent;
  transform: translateY(-3px);
}

.topic-card__link:hover::after {
  transform: scaleX(1);
}

.topic-card__title {
  font-family: var(--font-display);
  font-size: var(--font-size-2xl);
  font-weight: 500;
  letter-spacing: -0.02em;
  color: var(--color-primary);
  margin-top: auto;
  margin-bottom: var(--space-2);
  line-height: var(--line-height-tight);
}

.topic-card__description {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  line-height: var(--line-height-base);
}