*{box-sizing:border-box}body{margin:0;background:#f4f7fa;color:#15283b;font:17px/1.6 system-ui,-apple-system,'Segoe UI',sans-serif}a{color:var(--subject-colour);text-underline-offset:3px}.topic-wrap{width:min(1000px,calc(100% - 32px));margin:auto}.topic-top{background:#081a33;border-bottom:4px solid var(--subject-colour)}.topic-top .topic-wrap{display:flex;justify-content:space-between;align-items:center;gap:16px;flex-wrap:wrap;padding:10px 0}.topic-top a{color:white;display:inline-flex;align-items:center;min-height:44px}.topic-brand{font-size:21px;font-weight:850;text-decoration:none;letter-spacing:-.6px}.topic-brand span{color:var(--subject-light)}.topic-breadcrumb{display:flex;gap:8px;flex-wrap:wrap;font-size:14px;margin:18px 0 12px}.topic-breadcrumb a{min-height:44px;display:inline-flex;align-items:center}.topic-breadcrumb span{align-self:center;color:#50647b}.topic-intro{padding:4px 0 24px;max-width:790px}.topic-eyebrow{color:var(--subject-colour);font-size:14px;font-weight:800;letter-spacing:.04em;margin:0 0 8px}h1{font-size:clamp(29px,5vw,44px);line-height:1.15;letter-spacing:-.7px;margin:0 0 14px;overflow-wrap:anywhere}h2{font-size:24px;line-height:1.3;margin:0 0 12px}p{margin:0 0 16px}.topic-actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:20px}.topic-action{display:inline-flex;align-items:center;justify-content:center;min-height:48px;padding:10px 18px;border:1px solid var(--subject-colour);border-radius:9px;background:var(--subject-colour);color:white;font-weight:750;text-decoration:none;text-align:center}.topic-action.secondary{background:white;color:var(--subject-colour)}.topic-focus{padding:20px 24px;border-left:4px solid var(--subject-colour);background:var(--subject-tint);border-radius:0 12px 12px 0;margin:0 0 28px}.topic-focus h2{font-size:20px}.topic-focus ul{padding-left:21px;margin:0}.topic-focus li+li{margin-top:8px}.topic-resources{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:14px 0 28px}.topic-resource{background:white;border:1px solid #d7e1e8;border-radius:12px;padding:18px;text-decoration:none;color:#15283b;min-height:44px}.topic-resource strong{display:block;font-size:18px;color:var(--subject-colour);margin-bottom:4px}.topic-resource span{display:block;font-size:15px;color:#50647b}.topic-resource:hover,.topic-lesson:hover{border-color:var(--subject-colour);background:var(--subject-tint)}.topic-lessons{list-style:none;padding:0;margin:0 0 24px;display:grid;gap:9px}.topic-lesson{display:flex;align-items:center;gap:14px;padding:15px 18px;background:white;border:1px solid #d7e1e8;border-radius:10px;text-decoration:none;color:#15283b;min-height:60px}.topic-lesson>span:nth-child(2){min-width:0;flex:1}.topic-lesson strong{display:block;line-height:1.4;overflow-wrap:anywhere}.topic-lesson small{display:block;color:#50647b;font-size:14px;margin-top:2px}.topic-number{display:flex;align-items:center;justify-content:center;background:var(--subject-tint);color:var(--subject-colour);font-weight:800;border-radius:8px;min-width:47px;min-height:44px;font-size:15px}.topic-arrow{font-size:22px;color:var(--subject-colour)}.topic-tier{display:inline-block;color:var(--subject-colour);font-size:12px;font-weight:850;margin-bottom:3px}.topic-more{padding:24px;background:#e9eff5;border-radius:12px;margin:24px 0}.topic-more-links{display:flex;gap:8px 24px;flex-wrap:wrap}.topic-more-links a{display:inline-flex;align-items:center;min-height:44px}.topic-footer{border-top:1px solid #d7e1e8;padding:24px 0;color:#50647b;font-size:14px}.topic-skip{position:absolute;left:12px;top:-100px;background:white;padding:12px;z-index:5}.topic-skip:focus{top:12px}@media(max-width:600px){body{font-size:16px}.topic-resources{grid-template-columns:1fr;gap:8px}.topic-resource{padding:14px 16px}.topic-resource strong{font-size:17px}.topic-focus{padding:16px 18px}.topic-lesson{padding:12px;gap:10px}.topic-actions>a{flex:1 1 160px}.topic-breadcrumb{font-size:13px;gap:6px}.topic-more{padding:18px}.topic-top .topic-wrap{gap:8px}.topic-top a:last-child{font-size:14px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}
.topic-separate-note{border:1px solid #bddcc9;border-left:4px solid #198754;background:#eff9f3;border-radius:8px;padding:14px 18px;margin:0 0 20px;font-size:16px;line-height:1.5}.topic-separate-note[hidden]{display:none!important}.topic-separate-note>strong{color:#167846}.topic-separate-note p{margin:5px 0}.topic-separate-note>div{display:flex;gap:0 20px;flex-wrap:wrap}.topic-separate-note a{display:inline-flex;align-items:center;min-height:44px;font-weight:700}

html[data-subject="chemistry"] .topic-separate-note{border-color:#e6bab5;border-left-color:#b32624;background:#fff4f2}html[data-subject="chemistry"] .topic-separate-note strong,html[data-subject="chemistry"] .topic-separate-note a{color:#a12624}

/* Topic menus show the choices directly, without introductory feature copy. */
html[data-topic-menu] .topic-intro{padding-bottom:14px}
html[data-topic-menu] .topic-intro h1{margin-bottom:8px}
html[data-topic-menu] .topic-resources{margin:10px 0 14px;gap:10px}
html[data-topic-menu] a.topic-resource{display:flex;align-items:center;justify-content:center;padding:12px;min-height:48px;text-align:center;border-radius:8px}
html[data-topic-menu] a.topic-resource strong{margin:0;font-size:16px;line-height:1.35}
html[data-topic-menu] .topic-bank-link{margin:0 0 20px}
html[data-topic-menu] .topic-lesson{padding-block:12px;min-height:60px}
html[data-topic-menu] .topic-more{padding:16px 20px}
.topic-practical-links,.topic-source-links,.unit-source-links{display:flex;gap:8px 20px;flex-wrap:wrap;margin:16px 0}
.topic-practical-links a,.topic-source-links a,.unit-source-links a{display:inline-flex;align-items:center;min-height:44px}
@media(max-width:600px){
 html[data-topic-menu] .topic-resources{grid-template-columns:repeat(3,minmax(0,1fr));gap:7px}
 html[data-topic-menu] a.topic-resource{padding:10px 7px}
 html[data-topic-menu] a.topic-resource strong{font-size:14px}
 html[data-topic-menu] .topic-intro{padding-bottom:10px}
}