horizontal layout with relatively sized children

I have a horizontal layout with many children in a scrollview set with a minimum size, which displays well in-editor at about 300x200ish pixels, however when I build it to my phone which has a 1080p screen (1920x1080) all of the menu items are squished together.

Is there a way to say "I want each element to be at least 25% as wide as the parent" as with all other UI controls, because I have been unable to make this work with the scrollview.