/* JSQ concept narrative; all rules scoped to this page. */
.concept-page .page-head { padding-top: 54px; background: linear-gradient(135deg, #10213a, transparent); }
.concept-page h1 { font-size: clamp(36px, 4.6vw, 60px); font-weight: 700; line-height: 1.08; }
.concept-page .page-head .lede { max-width: 65ch; margin: 24px 0; font-size: 21px; line-height: 1.5; }
.concept-page .jump-links { gap: 4px 22px; margin-bottom: 0; font-size: 15px; }
.concept-page .jump-links a { text-decoration: none; border-bottom: 1px solid #355a83; }
.concept-section { max-width: var(--max); margin: 0 auto; padding: 48px var(--gutter); border-bottom: 1px solid var(--line); scroll-margin-top: 24px; }
.concept-section h2 { margin-bottom: 24px; max-width: 34ch; }
.concept-section h3 { font-size: 21px; margin-bottom: 12px; }
.concept-section p { max-width: 78ch; }
.concept-section .section-intro { max-width: 76ch; font-size: 20px; line-height: 1.5; margin-bottom: 26px; }
.concept-pair { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 36px 48px; }
.concept-pair > * { min-width: 0; }
.concept-pair p { color: #becbde; max-width: 54ch; }
.concept-page .foundations > div { border-top: 2px solid #355a83; padding-top: 24px; }
.concept-page .concept-standfirst { color: var(--ink); font-size: 19px; }
.concept-page .concept-aside { max-width: 96ch; margin: 24px 0 0; padding-left: 18px; border-left: 2px solid #355a83; color: #becbde; font-size: 15px; line-height: 1.65; }
.service-examples { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 28px 48px; }
.service-examples article { display: flex; gap: 18px; min-width: 0; padding: 22px 0 0; border-top: 1px solid var(--line); }
.service-examples p { color: #becbde; margin-bottom: 0; }
.concept-number { color: var(--brand-accent); font: 16px/1.7 var(--mono); }
.concept-page .practice { background: linear-gradient(135deg, #11213a, #0b1220); }
.concept-page .contact-steps { margin-bottom: 22px; }
.concept-page .contact-steps h3 { font-size: 21px; }
.concept-page .contact-steps p { color: #becbde; }
.layer-summary { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); border: 1px solid #355a83; border-radius: 8px; overflow: hidden; }
.layer-summary > div { padding: 22px 24px; background: var(--panel); }
.layer-summary > div + div { border-left: 1px solid #355a83; }
.layer-summary strong, .layer-summary span { display: block; }
.layer-summary strong { color: var(--brand-accent); font-size: 19px; margin-bottom: 8px; }
.layer-summary span { color: #becbde; }
.concept-details { border-top: 1px solid var(--line); margin-top: 28px; }
.concept-details summary { padding: 18px 0; cursor: pointer; font-weight: 700; color: #b4d7ff; }
.concept-details[open] summary { margin-bottom: 8px; }
.concept-details p { color: #becbde; }
.concept-page .source-links { display: flex; flex-wrap: wrap; gap: 10px 22px; font-size: 15px; margin-bottom: 0; }
.layer-diagram { margin: 6px 0 24px; text-align: center; }
.layer-diagram > div { padding: 16px; background: var(--panel); border: 1px solid #355a83; border-radius: 6px; }
.layer-diagram > div + div { margin-top: 18px; position: relative; }
.layer-diagram > div + div::before { content: ''; position: absolute; height: 18px; width: 1px; background: var(--brand-accent); top: -19px; left: 50%; }
.layer-diagram .layer-core { border-color: var(--brand-accent); color: var(--brand-accent); font-weight: 700; }
.layer-diagram .layer-modems { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); padding: 0; }
.layer-modems span { padding: 16px 8px; }
.layer-modems span + span { border-left: 1px solid #355a83; }
.layer-modems small { display: block; color: #becbde; margin-top: 6px; }
.delivery-evidence { margin: 0; border-top: 1px solid #355a83; }
.delivery-evidence > div { display: grid; grid-template-columns: 210px minmax(0, 1fr); gap: 20px; padding: 18px 22px; border-bottom: 1px solid var(--line); }
.delivery-evidence > div:nth-child(odd) { background: var(--panel); }
.delivery-evidence dt { color: #b4d7ff; font-weight: 700; }
.delivery-evidence dd { margin: 0; color: #becbde; }
.concept-page .example-line { border-left: 2px solid var(--brand-accent); padding-left: 16px; color: var(--ink); }
.relay-route { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 40px; padding: 24px; margin: 0 0 26px; list-style: none; background: var(--panel); border: 1px solid #355a83; border-radius: 8px; }
.relay-route li { position: relative; margin: 0; }
.relay-route li + li::before { content: '→'; position: absolute; left: -28px; color: var(--brand-accent); }
.relay-route strong, .relay-route span { display: block; }
.relay-route span { color: #becbde; margin-top: 6px; font-size: 15px; }
@media (max-width: 760px) {
  .concept-pair, .service-examples, .layer-summary { grid-template-columns: 1fr; }
  .layer-summary > div + div { border-left: 0; border-top: 1px solid #355a83; }
  .concept-page .page-head .lede, .concept-section .section-intro { font-size: 19px; }
  .delivery-evidence > div { grid-template-columns: 1fr; gap: 6px; padding: 16px; }
  .concept-section { padding-top: 36px; padding-bottom: 36px; }
}
@media (max-width: 520px) {
  .relay-route { grid-template-columns: 1fr; gap: 32px; }
  .relay-route li + li::before { content: '↓'; left: 0; top: -29px; }
}