Translate X and Y percentage values based on elements height and width?

Question

Translating an elements Y axis 50% will move it down 50% of its own height, not 50% of the parents height as I would expect. How do I tell a translating element to base it\'

Answer 1

What works for me using only CSS is:

.child {
    position: relative;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);

    /* Backward compatibility */
    -webkit-transform: translate(-50%, -50%);
    -moz-transform: translate(-50%, -50%);
    -o-transform: translate(-50%, -50%);
    -ms-transform: translate(-50%, -50%);
}

How it works:

• top and left positioning move child widget according to parent coordinates. Child widget's top-left corner will appear exactly in the center of parent (this is not what we want at this time).
• translation will move child widget -50% to top and left based on its size (not the parent). It means, widget's center point will be moved exactly where top-left point was - which previously was set up as center of a parent, and this is what we want.