One thing I have noticed in Safari 10 is the text on websites is smaller and there does not seem to be a preference, as in the old days, to set the minimum font size. You can send feedback to Apple here. I just submitted a comment, to the effect that I won't be upgrading to Safari 10 until this is fixed.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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