computer help needed please ....

not that important but its bugging me. Im on community classic forum and suddenly the lines got smaller hence text harder to read, as if row height got changed. Tried dragging out from corner and lines still thin, also tried changing from 10 to 5 posts per page and no change to lines. Also tried using spanner to increse to 110% but doesnt work on forum cos its not a main web page.

Any ideas please? Thx in advance