.b1-grid > *,
.section-head > *,
.ark-grid > *,
.model-grid > *,
.bridge-grid > * {
  min-width: 0;
}

@media (max-width: 640px) {
  .header-inner { gap: 9px; }
  .main-nav { gap: 7px; }
  .main-nav > a:not(.nav-featured):not(.language-link) { display: none; }
  .main-nav .nav-featured,
  .main-nav .language-link {
    padding: 6px 8px;
    font-size: .67rem;
  }
  .b1-hero h1 {
    max-width: 100%;
    font-size: clamp(2.35rem, 11vw, 3.5rem);
    letter-spacing: -.06em;
    overflow-wrap: anywhere;
  }
  .meta span { font-size: .61rem; }
  .evidence-strip,
  .history-flow,
  .doi-evidence { grid-template-columns: 1fr; }
  .doi-evidence { gap: 14px; padding: 25px; }
  .history-flow i {
    transform: rotate(90deg);
    text-align: center;
  }
}
/* Final spacing and readability polish */
.section-head {
  align-items: start;
  gap: clamp(30px, 5vw, 64px);
  margin-bottom: 56px;
}

.section-head > p {
  max-width: 620px;
}

.cards,
.governance-cards {
  gap: 16px;
}

.cards article {
  min-height: 220px;
  padding: 30px;
}

.ark-grid,
.model-grid {
  gap: clamp(36px, 6vw, 72px);
}

.ark-parts {
  gap: 14px;
}

.ark-parts small {
  display: block;
  margin-top: 7px;
  color: var(--muted);
  font-size: .74rem;
  line-height: 1.45;
}

.history-flow {
  gap: 18px;
}

.bridge-grid {
  align-items: start;
}

.bridge-links {
  grid-template-columns: 1fr;
  gap: 16px;
}

.bridge-links a {
  min-height: 0;
  padding: 32px;
}

.concept-flow {
  gap: 13px;
}

@media (max-width: 640px) {
  .section-head {
    margin-bottom: 36px;
  }

  .cards article {
    min-height: 0;
    padding: 24px;
  }

  .concept-map {
    padding: 24px;
  }

  .bridge-links a {
    padding: 25px;
  }
}

/* Keep labels readable on the light authority and infrastructure panels. */
.concept-flow .authority span,
.concept-flow .dark span {
  color: var(--teal-dark);
}

.concept-flow .authority small,
.concept-flow .dark small {
  color: #355b68;
}

.concept-flow .public span {
  color: var(--yellow);
}