[ggg9990]

And websites can sell static JPG ads that are impossible to block.

[dredmorbius]

s/impossible/harder/

One of the first adblock tools I used relied on thevstandard sizes of banner ads to blok them.

Names of selectors, XPATH, explicit element whitelisting, denying all image content, etc, all are possible options.

On desktop I apply a pretty rigorous set of CSS customisations against numerous sites.

Plus the usual adblocking.

[bscphil]

Are you thinking of Privoxy? I have good memories of using it - it was perhaps the second open source program I ever used after Firefox and really got me into coding in general because of how configurable it was.