/* Chapters provide the reading hierarchy; existing section layouts stay independent. */
.chapter{display:flow-root;margin-top:144px;--section-space:80px}
#chapter-case{margin-top:96px}
.chapter-header{display:flex;align-items:baseline;gap:22px;padding-bottom:24px;border-bottom:1px solid #d8d2c8;margin-bottom:64px}
.chapter-header.wrap{margin-bottom:64px}
.chapter-number{color:var(--accent);font-size:12px;font-variant-numeric:tabular-nums;letter-spacing:.04em}
.chapter-header h2{font-size:32px;font-weight:500;line-height:1.3;letter-spacing:-.04em;margin:0}
.chapter .section-heading h2,.chapter .models-copy h2{font-size:28px;line-height:1.45}
.chapter>.chapter-header+section{padding-top:0}
.chapter>.workflow-section.layout-workflow{margin-top:0;padding:0;background:transparent}
.chapter-tinted{background:#eeebe5;padding-block:72px 80px}
.chapter-tinted .source-reader,.chapter-tinted .comparison-window,.chapter-tinted .relationship-scene{border-color:#d8d1c6}
.chapter-tinted .source-paper{background:#faf8f3}
.chapter .layout-showcase{margin-top:80px}
.site-header nav a{position:relative;padding-block:12px}
.site-header nav a::after{content:"";position:absolute;left:0;bottom:4px;top:auto;width:22px;height:2px;border-radius:0;transform:scaleX(0);transform-origin:left;background:var(--accent);transition:transform .2s ease}
.site-header nav a.active::after{transform:scaleX(1)}
.site-header nav a.active{color:var(--ink);font-weight:500}
@media(max-width:1000px){.chapter{margin-top:120px}.chapter-header h2{font-size:30px}}
@media(max-width:760px){
 .chapter{margin-top:96px;--section-space:64px}
 .chapter-header.wrap{gap:16px;padding-bottom:20px;margin-bottom:40px}
 .chapter-header h2{font-size:28px}
 .chapter .section-heading h2,.chapter .models-copy h2{font-size:25px}
 .chapter-tinted{padding-block:48px 56px}
 .chapter .layout-showcase{margin-top:64px}
}
@media(max-width:620px){
 html{scroll-padding-top:130px}
 .site-header .header-inner{display:grid;grid-template-columns:1fr;gap:7px;height:auto;padding-block:12px 5px}
 .site-header nav{display:flex;justify-content:space-between;width:100%;margin:0;gap:12px;font-size:11px}
 .site-header nav a:nth-child(n){display:inline-flex;white-space:nowrap}
 .site-header .brand{justify-self:start;font-size:23px}
 .site-header .brand-mark{width:27px;height:27px;font-size:23px}
 .site-header .header-evidence{display:none}
 .chapter{scroll-margin-top:0}
}
@media(prefers-reduced-motion:reduce){.site-header nav a::after{transition:none}}