body,html{margin:0;padding:0;font-family:Arial,sans-serif;background:#111;color:#fff}*{box-sizing:border-box}.container{min-height:100vh;display:flex;justify-content:center;align-items:center;padding:20px}.box{width:100%;max-width:400px;background:#1e1e1e;padding:30px;border-radius:12px}input{background:#2b2b2b}button,input{width:100%;padding:12px;margin-top:10px;border:none;border-radius:8px;color:#fff}button{background:#00aaff;cursor:pointer}.list{margin-top:20px}.item{background:#2b2b2b;padding:10px;border-radius:8px;display:flex;justify-content:space-between;align-items:center}.error,.item{margin-top:10px}.error{color:red}.success{color:#00ff88;margin-top:10px}