center image html
.centered {
position: fixed;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
-webkit-transform: translate(-50%, -50%);
-moz-transform: translate(-50%, -50%);
-o-transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
font-size: 20px;
background-color: cyan;
border: darkgreen 5px solid;
padding: 5px;
z-index: 100;
}