I so agree with you @johnhs99.
I had my font set at 18 in Safari Pref and now after the update (done this morning) all I can do is use ZOOM. I'm constantly zooming in/out in Safari 10.0........ ⌘ +, ⌘- over and over again or clicking the zoom buttons in the menu bar. If I have the Page Zoom font set at 115%, it is too small to read and 125% has a lot of useless white space in the margins on the Google search page plus the description of the website is too small anyway. This is terrible UI planning. Why why why? You know, it's typical Apple, giveth and the permanently taketh away with an update.
Throughout the years, I've have given many feedback and bug reports to Apple and nothing ever gets fixed. Some of my bug reports became "duplicates" and then deactivated which means "it'll never be fixed" like the four finger swipe up to reveal what is actually in the Desktop Spaces instead of Desktop 1, Desktop 2 etc. That was taken away with El Capitan to be never seen again. I have no idea why something so useful would be taken away.
I rarely go on this Apple Support forum anymore since the entire UI changed and that irritating thin grey font. It's too much for my 54 year old eyes.
I'm just going to use Time Machine and downgrade. I can't deal with this new and improved (hahah) Safari.