css3: translateX to center element horizontally

Question

I\'m trying to center horizontally an element: jsfiddle

On the child I

Answer 1

You can do it by display flex and justify-content is center.

Example: http://jsfiddle.net/ugw9o3qp/1/

#parent {
    display: flex;
    justify-content: center;
    width: 300px;
    height: 100px;
    background-color: black;
    border: 1px solid grey;
}
#child {
    height: 100px;
    width: 20px;
    background-color:red;
}