body{font-family:Arial;background:#111;color:white;padding:20px}.box{background:#222;padding:20px;border-radius:20px;max-width:500px;margin:auto;margin-bottom:20px}input,button{width:100%;padding:12px;margin-top:10px;border:none;border-radius:10px}button{background:#4da3ff;color:white}.hidden{display:none}