.textbook-hub {padding-bottom:48px;}
.textbook-hub > section {margin-block:32px;}
.textbook-hub .page-intro {margin-top:32px;}
.textbook-grid {display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:24px;}
.textbook-grid .card {display:flex;flex-direction:column;gap:16px;padding:28px;}
.textbook-grid h2 {font-size:28px;}
.textbook-grid p {color:var(--muted);}
.textbook-grid strong {margin-top:auto;}
.textbook-back {display:inline-block;margin-bottom:16px;}
.textbook-chapter {margin-bottom:20px;}
.geometry-lesson {margin:0;}
.geometry-lesson > .shell > section {margin-block:0;}
.geometry-lesson .lesson-heading h1 {font-size:clamp(32px,5vw,46px);}
@media(max-width:700px){.textbook-grid {grid-template-columns:1fr;gap:16px;}.textbook-grid .card {padding:22px;}.textbook-grid h2 {font-size:25px;}}