Actually, almost every GUI toolkit's scheme for layout has issues, and none of them are perfect.

The ones that use absolute pixel positioning fail when using different resolution displays.

The ones that use box packing fail when you need to deal with different sized displays.

The ones that use constraint programming fail when you need to layout hundreds or thousands of widgets.

CSS-style layout has its own pros and cons, but there is no alternative to it that is clearly better under all circumstances. If you doing layout and want to be resolution-independent, function on everything from phones to giant displays and have thousands of things to layout, CSS is actually likely better than any alternative.