I've been working on the site https://founderspledge.com/ and just noticed that if you go to the main page, and open the Chrome console to view the source, there's an element that I certainly didn't put there:
<div class="pub_300x250 pub_300x250m pub_728x90 text-ad textAd
text_ad text_ads text-ads text-ad-links" style="position: absolute;">.</div>
It also doesn't show up when I run the site's code in localhost, or when I load the page source separately using Chrome's 'View Source' option.
I Googled the div's class list, and the top few hits were from anti-ad blocker software (eg https://github.com/sitexw/FuckAdBlock), which doesn't seem malign, but doesn't explain why it would be on this site.
1) How can I get rid of this element?
2) How might it have got there?
3) Does it imply there's a hole in the site's security?