html position absolute center

position: absolute;
margin-left: auto;
margin-right: auto;
left: 0;
right: 0;
text-align: center;

position: absolute;
margin-left: auto;
margin-right: auto;
left: 0;
right: 0;

position: absolute;
width: XXX; /* <-- !!! */
margin-left: auto;
margin-right: auto;
left: 0;
right: 0;
text-align: center;

.container {
  left:0;
  right:0;

  margin-left: auto;
  margin-right: auto;

  position: absolute;
  width: 40%;

  outline: 1px solid black;
  background: white;
}