I've just tried it and found the same as ANO.
I've then tried TheChair's solution and it does, indeed, work. However it relies on placing a cookie on your computer; if, like me, you delete all cookies at the end of every session, the 'small box' behaviour will keep returning.
However, ANO, I'm completely mystified as to why should ever need to use the Google search page anyway. (That was my first visit to it for years). Your previous posts suggest that you use Firefox. If so, it's far more efficient to use the search box at the top right of your page (which, by default, uses Google anyway but also allows you to search other sites if you prefer).