position div fixed in the middle code example
Example 1: how to middle fixed element
position: fixed;
top: 0;
z-index: 100;
left: 50%;
transform: translateX(-50%);
Example 2: how to center with position fixed
position: fixed;
width: 500px;
height: 200px;
margin: 5% auto; /* Will not center vertically and won't work in IE6/7. */
left: 0;
right: 0;