form { 
margin: 0 auto; 
width:250px;
}

#output {
margin: 0 auto;
width:250px;
color:white;
}

button { 
margin: 0 auto; 
width:275px;
}

img {
  display: block;
  margin-left: auto;
  margin-right: auto;
}

@-webkit-keyframes rotating {
    from {
        -webkit-transform: rotate(0deg);
    }

    to {
        -webkit-transform: rotate(360deg);
    }
}

.rotating {
    -webkit-animation: rotating 2s linear infinite;
}

#NOK{
background-color:red;
display: inline-block;
}

#OK
{
background-color:green;
display: inline-block;
}

#ERROR
{
background-color:red;
display: inline-block;
}