minSizeForChild

pub fn minSizeForChild(self: *BasicLayout, s: Size) Size {
        switch (self.dir) {
            .vertical => {
                // add heights
                self.min_size_children.h += s.h;

                // max of widths
                self.min_size_children.w = @max(self.min_size_children.w, s.w);
            },
            .horizontal => {
                // add widths
                self.min_size_children.w += s.w;

                // max of heights
                self.min_size_children.h = @max(self.min_size_children.h, s.h);
            },
        }

        return self.min_size_children;
    }