body{font-family:Inter,system-ui,Arial,sans-serif;background:#f4f6fb;color:#111;margin:0}.container{max-width:900px;margin:24px auto;padding:12px}header h1{margin:0 0 12px}.card{background:#fff;padding:12px;margin-bottom:12px;border-radius:8px;box-shadow:0 1px 3px #0000000f}.row{margin:8px 0}input[type=number],select{padding:6px 8px;margin-left:8px}button{margin-right:8px;padding:8px 12px;border-radius:6px;cursor:pointer}.muted{color:#666;font-size:.9rem}.result{margin-top:12px;background:#f7fafc;padding:8px;border-radius:6px}