My monitor is 2560px wide. When I shrink my browser down to 1920px, the text boxes collapses to only 100px wide. So I'd say it's both that Frenchy is using a higher DPI, and that vg's resolution is probably standard 1920px width.
That's still a problem because most monitors are going to be 1080p. Though in both cases the userstyle from above should do the job.