body{color:#222;background:#f4f6f8;margin:0;font-family:Arial,sans-serif}.app{max-width:700px;margin:40px auto;padding:20px}h1{text-align:center}.card{background:#fff;border-radius:12px;margin-top:20px;padding:20px;box-shadow:0 4px 14px #0000001a}input{width:100%;margin-top:10px;margin-bottom:15px;padding:12px;font-size:18px;display:block}button{cursor:pointer;padding:12px 20px;font-size:16px}#result{margin-top:15px;font-weight:700}