Problem with text Sight theme (no changes to CSS)

I installed the Sight theme without changing anything in the CSS (in fact, everything is its original theme). There are occasional problems where the text condenses down to tiny little lines. It can usually be fixed with refreshing the page, but I haven’t seen a problem with it in other sites that use the same layout. Does anyone know a way I might be able to fix this? Why does it do this?

Looks like this sometimes

Should look like this all the time