Centering Percentage Width/Height Elements

gistfile1.css

.center {
    position: absolute;
    left: 50%;
    top: 50%;
    
    /*
    Nope =(
    margin-left: -25%;
    margin-top: -25%;
    */  
    /* 
    Yep!
    */
    transform: translate(-50%, -50%);
    
    /*
    Not even necessary really. 
    e.g. Height could be left out!
    */
    width: 40%;
    height: 50%;
}