Center Position Fixed Horizontally

I want to dynamically append to the end of the body a fixed-positioned to the bottom box that has 1000px width and is centered horizontally. When I create it with percentage width

Solution 1:

Try this also:

div{
  position: fixed; 
  bottom: 0; 
  width: 1000px; 
  left: 50%;
  transform:translateX(-50%);
  height: 100px; 
  background-color: green;
}

Solution 2:

http://jsfiddle.net/eesry2ss/

body:after {
    content:"";
    width: 1000px;
    height: 100px;
    position: fixed;
    left: 50%;
    bottom:0;
    margin-left: -500px;
    background-color:green;
}

Solution 3:

Try this:

div{
  position: fixed; 
  bottom: 0; 
  width: 1000px; 
  left: 50%;
  margin-left: -500px;
  height: 100px; 
  background-color: green;
}

<div></div>

Solution 4:

Try CSS3, to avoid giving calculated values in pixel for your margins.

left:50%;
transform: translateX(-50%);

Here's a demo: https://jsbin.com/zejutisabo/edit?html,css,output