/* Editorial chapter covers. Native details remain usable without JavaScript. */
.project-section__inner--chapter { padding-block: 0; }
.chapter-cover { display: grid; grid-template-columns: var(--space-32) minmax(0, 1fr) auto; gap: var(--space-24); align-items: start; padding-block: 20px; list-style: none; cursor: pointer; }
.chapter-cover::-webkit-details-marker { display: none; }
.chapter-cover::marker { content: ''; }
.chapter-number { padding-top: 6px; color: var(--color-accent); font-size: var(--project-type-micro); line-height: var(--leading-small); letter-spacing: .08em; font-variant-numeric: tabular-nums; }
.chapter-cover-copy { min-width: 0; }
.chapter-cover-copy .section-heading { color: var(--ink); font-size: var(--project-type-section); font-weight: var(--project-weight-section); line-height: 1.3; text-wrap: balance; }
/* Outranks .project-story p so Overview / Research covers share the same summary scale. */
.chapter-cover .chapter-summary { margin: 6px 0 0; max-width: 80ch; color: var(--muted); font-size: var(--project-type-subtitle); font-weight: var(--weight-regular); line-height: var(--project-leading-body); }
.chapter-action { display: inline-flex; align-items: center; justify-content: end; min-height: var(--control-size); padding-block: var(--space-8); border-bottom: var(--border-subtle); color: var(--color-link); font-size: var(--project-type-small); line-height: var(--leading-small); white-space: nowrap; transition: color var(--duration-feedback) var(--ease-feedback), border-color var(--duration-feedback) var(--ease-feedback); }
.chapter-cover:hover .chapter-action { color: var(--color-accent); border-color: currentColor; }
.chapter-cover:focus-visible { outline: 1px solid var(--color-focus); outline-offset: 4px; border-radius: var(--radius-sm); }
.chapter-body { overflow: visible; }
.chapter-content { padding-top: var(--space-12); padding-bottom: var(--space-32); display: flow-root; font-size: var(--project-type-body); font-weight: var(--weight-regular); line-height: var(--project-leading-body); }
.chapter-pending { margin: 0; color: var(--muted); font-size: var(--project-type-body); line-height: var(--project-leading-body); }
/* Retained diagram / concept intro columns; Overview now fills its own balanced text grid. */
.chapter-content .concept-heading > div, .chapter-content .flow-intro > p { grid-column: 2; }
.chapter-content .drone-design-intro > p { margin-top: 0; }
@media (max-width: 1024px) { .chapter-cover { grid-template-columns: var(--space-32) minmax(0, 1fr) auto; gap: var(--space-16); } }
@media (max-width: 760px) {
  .chapter-cover { grid-template-columns: var(--space-16) minmax(0, 1fr) auto; gap: var(--space-8); }
  .chapter-action { justify-self: end; }
  .chapter-content .concept-heading > div, .chapter-content .flow-intro > p { grid-column: 1; }
}
@media (prefers-reduced-motion: reduce) { .chapter-action { transition: none; } }