:root{--teal: #47c0bb;--teal-soft: rgba(71, 192, 187, .12);--teal-mid: rgba(71, 192, 187, .5);--diff-easy: #58b33c;--diff-medium: #ffe753;--diff-hard: #f46b5d;--diff-failed: #ae96bb;--bg: #ffffff;--text: #1c1c1e;--muted: #8e8e93;--card: #f5f5f7;--border: #e2e2e6;--radius: 14px;--radius-lg: 20px}*{box-sizing:border-box}html,body,#root{margin:0;height:100%}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;color:var(--text);background:var(--bg);-webkit-font-smoothing:antialiased}button{font-family:inherit;cursor:pointer}.app-shell{max-width:480px;margin:0 auto;min-height:100%;display:flex;flex-direction:column;padding:16px}.btn{border:none;border-radius:var(--radius);padding:14px 18px;font-size:17px;font-weight:600;background:var(--teal);color:#fff}.btn:disabled{opacity:.5}.btn-secondary{background:var(--card);color:var(--teal)}.btn-ghost{background:transparent;color:var(--teal);padding:8px}.card{background:var(--card);border-radius:var(--radius);padding:14px}.muted{color:var(--muted)}.center{text-align:center}.row{display:flex;align-items:center;gap:12px}.col{display:flex;flex-direction:column}.spacer{flex:1}.stack>*+*{margin-top:12px}input.field{width:100%;padding:12px;border:1px solid var(--border);border-radius:10px;font-size:16px}.diff-easy{color:var(--diff-easy)}.diff-medium{color:var(--diff-medium)}.diff-hard{color:var(--diff-hard)}.diff-failed{color:var(--diff-failed)}