Vertical borders in tables (and other elements) don't work

Why vertical borders don't work on Opera Mini? It behaves really strange. Borders work only in the initial view, like here on the Opera page itself:

http://i.imgur.com/xtdrl8A.png

You can see the vertical line, but if you scroll down...

http://i.imgur.com/DCB8eYL.png

The vertical line was not generated below. You can also see the full table, where there are no vertical borders. Is there a way around it? I noticed if you use some tags it does work, like H2.

I use Opera for Android 7.6.40234, but I've managed to replicate it on many others including Microemulator.