.substitution-understand{display:block;min-width:0}.substitution-understand__panel{display:grid;gap:var(--space-4);padding:var(--space-5);border:1px solid var(--border-subtle);border-radius:var(--radius-lg);background:var(--surface-base)}.substitution-understand__header{display:grid;gap:var(--space-2)}.substitution-understand__header h3{margin:0;font-size:clamp(1.25rem,2vw,1.65rem)}.substitution-understand__eyebrow,.substitution-understand__tag,.substitution-workspace__status{font-size:.78rem;font-weight:700;letter-spacing:.03em}.substitution-understand__eyebrow{color:var(--mode-accent)}.substitution-understand__body{display:grid;gap:var(--space-4)}.substitution-understand__lead{margin:0;max-width:72ch}.substitution-understand__compare,.substitution-understand__grid,.substitution-understand__choice-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:var(--space-3)}.substitution-understand__grid{grid-template-columns:repeat(4,minmax(0,1fr))}.substitution-understand__choice-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.substitution-understand__card,.substitution-workspace{display:grid;gap:var(--space-3);padding:var(--space-4);border:1px solid var(--border-subtle);border-radius:var(--radius-md);background:var(--surface-raised)}.substitution-understand__card p,.substitution-workspace p{margin:0}.substitution-understand__answer{font-weight:700}.substitution-workspace__head{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:var(--space-2)}.substitution-workspace__expression,.substitution-workspace__stage-expression{font-family:var(--font-maths,inherit)}.substitution-workspace__status{padding:.3rem .55rem;border-radius:999px;background:var(--feedback-info-soft);color:var(--feedback-info-accent)}.substitution-workspace__status.is-unhelpful{background:var(--feedback-incorrect-soft);color:var(--feedback-incorrect-accent)}.substitution-workspace__cues{margin:0;padding-left:1.2rem}.substitution-workspace__rail{display:grid;gap:var(--space-2);margin:0;padding:0;list-style:none}.substitution-workspace__stage{display:grid;gap:.2rem;padding:var(--space-3);border-left:3px solid var(--mode-accent);background:var(--mode-soft);border-radius:var(--radius-sm)}.substitution-workspace__stage[data-variable-state="invalid"]{border-left-color:var(--feedback-incorrect-accent);background:var(--feedback-incorrect-soft)}.substitution-workspace__stage-label,.substitution-workspace__limits{font-size:.8rem}.substitution-workspace__warning,.substitution-understand__warning{color:var(--feedback-incorrect-accent);font-weight:700}.substitution-understand__checklist{display:grid;gap:var(--space-2)}.substitution-understand__check{display:grid;grid-template-columns:auto 1fr;gap:var(--space-2);align-items:start;padding:var(--space-3);border-radius:var(--radius-sm);background:var(--mode-soft)}.substitution-understand__checkmark{display:grid;place-items:center;min-width:2rem;min-height:2rem;border-radius:50%;background:var(--surface-base);font-weight:800;color:var(--mode-accent)}
@media (max-width:900px){.substitution-understand__grid{grid-template-columns:repeat(2,minmax(0,1fr))}.substitution-understand__choice-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:680px){.substitution-understand__panel{padding:var(--space-4)}.substitution-understand__compare,.substitution-understand__grid,.substitution-understand__choice-grid{grid-template-columns:1fr}.substitution-workspace__head{align-items:flex-start;flex-direction:column}}