Q: In Safari, the screen zooms in making it hard to read without scrolling back and forth.  Doesn't happen with a wired mouse.

In Safari, why does the screen zoom in for no reason, making it hard to read?  This does not happen if I use a wired mouse.  I have not clicked on the arrow in the upper right - so it seems to just happen for no reason, andI cant get it to shrink without leaving the window.