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Please edit your question and give us more details. What operating system are you using? Mobile or desktop site? What browser? Have you reset the zoom level? Does this also happen if you open the page in an incognito window?
You should be able to open a private window, one where none of your extensions or userscripts are active. In seamonkey, I believe it's File -> New -> Private Window. Try loading a page with that and see if you still have the issue. Also, please clarify whether this happens on all pages of Ask Ubuntu, or only one, or if it is a general thing happening on other sites as well.
It only happens on a few pages of Ask Ubuntu. It never happens at other sites. Next time I see it, I will copy and paste it and see if it's readable. @terdon