.activity-shell{max-width:960px;margin:0 auto}.activity-intro .callout,.builder-tool{margin-top:1rem}.builder-parents{display:grid;gap:1rem;grid-template-columns:1fr 1fr;margin-bottom:1.25rem}.parent-group h4{margin:0 0 .4rem;font-size:.95rem}.preset-btns{display:flex;flex-wrap:wrap;gap:.35rem}.preset-btn{border:1px solid var(--color-border);background:var(--color-bg);border-radius:999px;padding:.35rem .7rem;font-size:.85rem;cursor:pointer;color:var(--color-ink)}.preset-btn:hover{border-color:var(--color-primary)}.preset-btn.selected{background:var(--color-primary);color:#fff;border-color:var(--color-primary)}.builder-output{display:grid;gap:1.25rem;grid-template-columns:auto 1fr;align-items:center}.builder-ratios>div{padding:.3rem 0;border-bottom:1px dashed var(--color-border);font-size:1rem}.builder-ratios>div:last-child{border-bottom:0}.ratio-key{display:inline-block;min-width:9.5rem;color:var(--color-ink-soft);font-weight:600;font-size:.82rem;text-transform:uppercase;letter-spacing:.03em}.challenge-layout{display:grid;grid-template-columns:minmax(250px,.82fr) minmax(0,1.18fr);gap:1rem;align-items:start}.challenge-context{display:grid;gap:1rem}.context-square-card{background:#fffdfa;border:1px solid #eadfc7;border-radius:var(--radius);box-shadow:var(--shadow);padding:1rem}.context-square-card .eyebrow{color:#9a6d18;margin-bottom:.35rem}.context-square-card h3{color:var(--color-ink);font-size:1.05rem;margin-bottom:.35rem}.context-square-card .grid-host{margin:.55rem 0 .75rem}.context-square-card table.punnett th,.context-square-card table.punnett td{width:48px;height:48px}.context-square-card table.punnett td.filled{font-size:1.05rem}.context-ratios>div{font-size:.88rem;padding:.25rem 0}.context-ratios .ratio-key{min-width:7.2rem;font-size:.7rem}.lt-tag{margin-bottom:.9rem}.question-text{font-size:1.15rem;font-weight:600;margin:0 0 1rem;color:var(--color-ink)}.build-hint{font-size:.9rem;margin:-.3rem 0 .3rem}.options{list-style:none;margin:0;padding:0;display:grid;gap:.6rem}.option-btn{display:block;width:100%;text-align:left;padding:.8rem 1rem;border:1px solid var(--color-border);border-radius:10px;background:var(--color-bg);color:var(--color-ink);font-size:1rem;cursor:pointer;transition:border-color .12s ease,background .12s ease}.option-btn:hover:not(:disabled){border-color:var(--color-primary);background:var(--color-sky)}.option-btn:disabled{cursor:default}.option-btn.correct{border-color:#2f9e63;background:#e3f5ea;color:#1d6b41;font-weight:600}.option-btn.incorrect{border-color:#d9534f;background:#fbe9e8;color:#a4302c;font-weight:600}.option-btn .mark{float:right;font-weight:700}.lt-breakdown{max-width:520px}.results-actions{margin-top:1rem}@media (min-width: 860px){.challenge-context{position:sticky;top:88px}}@media (max-width: 859px){.activity-shell{max-width:760px}.challenge-layout{grid-template-columns:1fr}.challenge-context{position:static}}@media (max-width: 620px){.builder-parents,.builder-output{grid-template-columns:1fr}.context-square-card table.punnett th,.context-square-card table.punnett td{width:46px;height:46px}}