Using CSS3 Flex-box
Simple Cascading Stylesheet rules to vertically and horizontally center your HTML contexts using flex-box.
html,body{
height: 100%;
margin:0;
padding: 0;
}
body{
display: flex;
align-items: center;
justify-content: center;
}
And there it is, all your contents centered. It's also responsive to any screen sizes.