.problem-tabs{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:32px 0}
.problem-tabs a{padding:18px 20px;border:1px solid var(--line2);border-radius:12px;background:var(--panel);transition:border-color .15s,background .15s}
.problem-tabs a:hover{border-color:var(--accent)}.problem-tabs a.on{border-color:var(--accent);background:#122036}
.problem-tabs strong{display:block;font:600 18px var(--display)}.problem-tabs small{display:block;color:var(--muted);margin-top:6px;font-size:13px;line-height:1.5}
.problem-tabs a.on strong{color:var(--accent)}.problem-section-head{margin:26px 0}.problem-section-head h2{font-size:28px;line-height:1.2}.problem-section-head p{color:var(--muted);margin-top:12px;max-width:80ch}
.math-notes{display:block;width:100%;resize:vertical;min-height:120px;padding:14px;border:1px solid var(--line2);border-radius:10px;background:var(--bg);color:var(--text);font:inherit;line-height:1.6}
.math-equation{margin-top:18px;padding:16px;border-radius:8px;background:var(--bg);font:500 16px/1.7 ui-monospace,Consolas,monospace;white-space:pre-wrap;overflow-wrap:anywhere;color:var(--accent)}
.math-steps{padding-left:22px;margin:18px 0 0}.math-steps li{padding-left:6px;margin:12px 0;line-height:1.7}.math-reference{font-size:13px;color:var(--muted);margin:30px 0}.math-reference a{color:var(--accent);text-decoration:underline;text-underline-offset:3px}
#problemMath select:focus-visible,#problemMath summary:focus-visible,.math-notes:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
@media(max-width:720px){.problem-tabs{grid-template-columns:1fr;gap:9px}.problem-tabs a{padding:14px 16px}.problem-tabs strong{font-size:17px}.problem-tabs small{margin-top:3px}}