.concept-main {
  padding-bottom: 96px;
}

.concept-hero {
  padding: 72px 0 58px;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(circle at 18% 0%, rgba(0, 178, 195, 0.11), transparent 28rem),
    rgba(9, 18, 24, 0.55);
}

.concept-shell {
  width: min(920px, calc(100% - 48px));
  margin-inline: auto;
}

.concept-breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 34px;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

.concept-breadcrumbs a {
  display: inline-flex;
  min-height: 32px;
  align-items: center;
  color: var(--text-soft);
}

.concept-breadcrumbs a:hover,
.concept-breadcrumbs a:focus-visible {
  color: var(--accent);
}

.concept-hero h1 {
  max-width: 16ch;
  margin-bottom: 24px;
  font-size: clamp(2.8rem, 6.5vw, 5.8rem);
}

.concept-deck {
  max-width: 760px;
  margin-bottom: 26px;
  color: var(--text-soft);
  font-size: clamp(1.04rem, 1.7vw, 1.2rem);
  line-height: 1.72;
}

.concept-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  margin: 0;
  padding: 0;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  list-style: none;
}

.concept-definition {
  margin: -1px auto 0;
  padding: 30px 0;
  border-block: 1px solid var(--line);
  background: rgba(0, 178, 195, 0.035);
}

.concept-definition p {
  width: min(920px, calc(100% - 48px));
  margin: 0 auto;
  color: var(--text);
  font-size: clamp(1.05rem, 2vw, 1.26rem);
  line-height: 1.68;
}

.concept-article {
  width: min(920px, calc(100% - 48px));
  margin: 0 auto;
  padding-top: 54px;
}

.concept-section {
  padding: 44px 0;
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 100px;
}

.concept-section:first-child {
  padding-top: 0;
}

.concept-section h2 {
  max-width: 18ch;
  margin-bottom: 18px;
  font-size: clamp(1.8rem, 4vw, 3rem);
}

.concept-section h3 {
  margin-top: 30px;
  margin-bottom: 10px;
}

.concept-section > p,
.concept-section li {
  color: var(--text-soft);
}

.concept-section > p {
  max-width: 760px;
}

.concept-section strong {
  color: var(--text);
}

.concept-list {
  display: grid;
  gap: 11px;
  max-width: 760px;
  margin: 20px 0 0;
  padding-left: 22px;
}

.concept-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 24px;
}

.concept-card {
  min-height: 180px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(13, 23, 29, 0.68);
}

.concept-card h3 {
  margin-top: 0;
}

.concept-card p {
  margin-bottom: 0;
  color: var(--text-soft);
  font-size: 0.9rem;
}

.concept-card-accent {
  border-color: rgba(0, 178, 195, 0.34);
  background: rgba(0, 178, 195, 0.05);
}

.concept-proof-chain {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 12px;
  margin: 24px 0;
  padding: 18px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: #050b0f;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.concept-code {
  overflow-x: auto;
  margin: 24px 0 0;
  padding: 22px;
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  background: #050b0f;
  color: #d7e8ee;
  font-size: 0.82rem;
  line-height: 1.8;
  tab-size: 2;
}

.concept-callout {
  margin: 26px 0 0;
  padding: 20px 22px;
  border-left: 2px solid var(--accent);
  background: rgba(0, 178, 195, 0.045);
}

.concept-callout p {
  margin: 0;
  color: var(--text-soft);
}

.concept-callout strong {
  color: var(--text);
}

.concept-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.concept-related {
  padding-top: 52px;
}

.concept-related h2 {
  margin-bottom: 22px;
  font-size: clamp(1.7rem, 3vw, 2.4rem);
}

.concept-related-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.concept-related-link {
  display: grid;
  gap: 7px;
  min-height: 44px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(13, 23, 29, 0.6);
  transition:
    border-color 160ms ease,
    transform 160ms ease;
}

.concept-related-link:hover,
.concept-related-link:focus-visible {
  transform: translateY(-1px);
  border-color: rgba(0, 178, 195, 0.42);
}

.concept-related-link strong {
  color: var(--text);
}

.concept-related-link span {
  color: var(--text-muted);
  font-size: 0.86rem;
}

.concept-footer {
  margin-top: 72px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}

.concept-footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.concept-footer-brand {
  display: grid;
  gap: 8px;
}

.concept-footer-brand p {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.84rem;
}

.concept-footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 6px 14px;
  color: var(--text-soft);
  font-size: 0.84rem;
}

.concept-footer-links a {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  padding-inline: 4px;
}

.concept-footer-links a:hover,
.concept-footer-links a:focus-visible {
  color: var(--accent);
}

.resource-card {
  display: block;
  color: inherit;
  transition:
    transform 160ms ease,
    border-color 160ms ease,
    background 160ms ease;
}

.resource-card:hover,
.resource-card:focus-visible {
  transform: translateY(-2px);
  border-color: rgba(0, 178, 195, 0.38);
  background: rgba(0, 178, 195, 0.055);
}

.resource-card .text-link {
  display: inline-block;
  margin-top: 18px;
  color: var(--accent);
}

@media (max-width: 760px) {
  .concept-grid,
  .concept-related-grid {
    grid-template-columns: 1fr;
  }

  .concept-footer-inner {
    display: grid;
  }

  .concept-footer-links {
    justify-content: flex-start;
  }
}

@media (max-width: 640px) {
  .concept-shell,
  .concept-definition p,
  .concept-article {
    width: min(100% - 32px, 920px);
  }

  .concept-hero {
    padding-top: 54px;
  }

  .concept-hero h1 {
    font-size: clamp(2.5rem, 13vw, 4rem);
  }

  .concept-section {
    padding: 36px 0;
  }

  .concept-proof-chain {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  .concept-related-link,
  .resource-card {
    transition: none;
  }
}