css freeze div in middle code example

Example 1: vertically and horizontally center a fixed div

// you dont need to know the divs dimensions and it does not require any container divs
position: fixed; 
top: 50%;
left: 50%;
transform: translate(-50%, -50%);

Example 2: how to center a position fixed element horizontally

left: 50%;
margin-left: -400px; /* Half of the width */