body{

margin:0;
font-family:Arial;
color:white;

background:linear-gradient(45deg,#0f2027,#203a43,#2c5364);
background-size:400% 400%;

animation:anim 10s infinite;

}

@keyframes anim{

0%{background-position:0% 50%}
50%{background-position:100% 50%}
100%{background-position:0% 50%}

}

.painel{

background:#000000cc;
padding:40px;
width:300px;
margin:100px auto;
border-radius:10px;
text-align:center;

}

button{

padding:10px;
width:100%;
margin-top:10px;
background:#ff3b3b;
border:none;
color:white;

}