I *think* I have left clicked in the message window, held down the "ctrl" button while hitting "+" (plus) or "-" (minus) which expands or reduces the text size.
This works on any "page", but you have to click in the message window to localize it there. Really helps to read pages with tiny text. You *might* have to use the right/left arrows to scroll across the page if you enlarge it too many times. each time you hold down "ctrl" and hit "+" it gets bigger, and use the opposite "-" (minus) to return to the original text size..
Some of you already know this, but............

Big Bear