Vertical Layout with Pixel Perfect scaling

I've got a bunch of UIs made with layout groups on a pixel perfect canvas. I've recently realized that my line segment element, separating header from content, (height of 1px) is getting presumably re-scaled along with all other elements and thus disappearing. I've set up a min-height of 1 on this element but it still disappears once you change the res. Here are pictures of higher res and lower res:

Proper behaviour



Re-scaled UI with missing line...

Vertical Layout with Pixel Perfect scaling