body{margin:0}.app{max-width:800px;margin:0 auto;padding:2rem}.card{border:1px solid #ccc;border-radius:4px;margin-bottom:1.5rem;padding:1.5rem}.btn{cursor:pointer;padding:.5rem 1rem}.btn:disabled{opacity:.6;cursor:not-allowed}.input-group{align-items:center;gap:.5rem;margin:1rem 0;display:flex}.response-box{border:1px solid #ccc;margin-top:1rem;padding:.5rem}.response-box pre{margin:0;overflow-x:auto}