Can't make it smaller as this will add too many words to the line - I'm at the upper limit as it is for good readability. Any bigger and will start to look like a ladybird book.On a phone it actually looks great because you want it as minimal as possible. And the text is the right size. But on a PC it needs some more attention. I don't have a tablet to hand at the moment.
The font size is the browser default. I prefer to leave it like this as it won't override local settings.