title: CSS: Centering a content with fixed position
body: <p>I'm having trouble with keeping a layer both fixed and centered at the same time. I can't apply margin: auto as my layer doesn't have any width value, it's a fulid thing.</p>
  
  <p>I found this one: <a href="https://stackoverflow.com/a/1777282/2114455">https://stackoverflow.com/a/1777282/2114455</a></p>
  
  <p>It's a great solution to center the layer, but how do I keep this centered layer fixed (I mean, no move when scrolling)</p>
  
  <p>I put them all in a position: fixed; div but this did not work. Any solution?</p>