CSS

center position fixed element

.centered {
    position: fixed;
    left: 50%;
    transform: translate(-50%, 0);
}

css position fixed center

.center {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, 0);
}

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;

centering a fixed item

.centered {
    position: fixed;
    left: 50%;
    transform: translate(-50%, 0);
}