Resizing the Safari browser.

Up until recently the Safari internet browser has been the default size, taking a space that is about half the width of the screen.

The browser now spans the entire width of the screen, and because most websites seem to be formatted for the smaller size, the sites are stretched.

I'm not entirely sure how the width was altered, but I cannot fix it.

I was wondering how I would be able to reduce the width of the Safari browser, back to the default setting.

Any assistance would be appreciated.