Getting percentages to work in CSS calc() for Firefox and Safari?

Question

I\'m using the following calc() equation to calculate the width of two divs:

CSS

.MyClass {
    width: calc((100% - 800px) / 2);
    wid         


        

Answer 1

The reason for this not working is that the parent element does not have height value defined.

It is strange but it works for Chrome and it does not need defined height, but that is not the case for Firefox

If you have:

put:

.parent {
    height: 100%;
}

and it should be ok.