.residential-expansion{margin-top:2.5rem}.residential-grid{gap:1.25rem}.residential-card{border-top:6px solid var(--blue)}.residential-card h3{color:var(--course-deep);font-size:1.45rem}.residential-card .button,.residential-shell .button{background:var(--blue);color:#fff;border-color:var(--blue)}.residential-card .button.secondary,.residential-shell .button.secondary{background:var(--course-soft);color:var(--course-deep)}.residential-color{display:flex;align-items:center;gap:.5rem;font-size:.9rem;font-weight:600}.residential-color span{width:1rem;height:1rem;background:var(--blue);border-radius:50%}.residential-tabs,.residential-controls{display:flex;flex-wrap:wrap;gap:.7rem;margin:1.4rem 0}.residential-tabs .button[aria-pressed=true]{outline:3px solid var(--course-deep);outline-offset:3px}.residential-lessons{display:grid;gap:.8rem;margin:1.4rem 0}.residential-lessons .card{margin:0}.residential-lessons summary{cursor:pointer;font-size:1.05rem;font-weight:650;line-height:1.6}.lesson-number{color:var(--blue);margin-right:.5rem}.residential-shell summary{cursor:pointer}.residential-flashcard{min-height:300px;border-top:6px solid var(--blue)}.residential-answer{padding:1rem;margin-top:1rem;background:var(--course-soft);border-left:4px solid var(--blue)}.residential-shell li{margin-bottom:1rem;line-height:1.6}.residential-shell .button:disabled{opacity:.65;cursor:not-allowed}.residential-shell .notice{background:var(--course-soft);color:var(--course-deep)}@media(max-width:600px){.residential-tabs .button{flex:1 1 45%;white-space:normal}.residential-card .course-actions .button{width:100%}}