is there a default for text size
Text size varies between 12pt and about 8pt - there does not seem tro be any logic that determines which. Size can be adjusted using CTL/+/- but you don't want to do this on every other page.
Alle svar (1)
Actually, text on the page is sized by the person who makes the page. generally, web designers do pick something between 8pt and 12pt, but they can pick really any size they want. If you want to change to the default size that the page was designed in, it's CTRL and 0 (Zero, not the letter 'o', this font is bad at sowing the difference).
CTRL+/- is something that browsers have added to help people read text if the size the designer picked is difficult for them to read.