:root{--blue:#2563eb;--navy:#172033;--muted:#64748b;--bg:#f8fafc;--card:#fff;--line:#e2e8f0;--green:#166534}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--navy);font:16px/1.5 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}header{background:linear-gradient(135deg,#1d4ed8,#2563eb);color:#fff;padding:1.25rem 1rem 2rem}nav,main,footer{width:min(760px,calc(100% - 2rem));margin:auto}nav{display:flex;justify-content:space-between;align-items:center}nav a{color:#fff;text-decoration:none;font-weight:800}.breadcrumbs{margin:2rem 0 1rem}.breadcrumbs a{color:var(--blue)}.calculator{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:1.5rem;box-shadow:0 4px 12px #0f172a0d}.field{margin:1rem 0}.field label{display:block;font-weight:650;margin-bottom:.35rem}input{width:100%;padding:.75rem;border:1px solid var(--line);border-radius:8px;font:inherit;background:#fff}input[type=checkbox]{width:auto;margin-right:.5rem}button{width:100%;border:0;border-radius:8px;background:var(--blue);color:#fff;padding:.8rem;font:inherit;font-weight:700;cursor:pointer}.result{margin-top:1.25rem;padding:1rem;background:#f0fdf4;color:var(--green);border-radius:8px;font-weight:700}footer{padding:2rem 0;color:var(--muted);font-size:.85rem;text-align:center}.ad{min-height:90px;display:grid;place-items:center;margin:2rem 0;border:1px dashed #a5b4fc;background:#eef2ff;color:var(--muted);font-size:.85rem}