body,html{margin:0;padding:0;font-family:Arial,sans-serif;background:#111;color:#fff}*{box-sizing:border-box}.container{height:100vh;display:flex;justify-content:center;align-items:center}.box{width:350px;background:#1e1e1e;padding:30px;border-radius:12px;box-shadow:0 0 20px rgba(0,0,0,.5)}h1{text-align:center;margin-top:0}input{margin-top:10px;background:#2b2b2b}button,input{width:100%;padding:12px;border:none;border-radius:8px;color:#fff}button{margin-top:15px;background:#00aaff;cursor:pointer}.error{margin-top:10px;text-align:center;color:red}