I think it would be a good idea to not show the initial result when the page is first loaded. The first thing I tried on the page was to click the Run button wi

I think it would be a good idea to not show the initial result when the page is first loaded. The first thing I tried on the page was to click the Run button without changing the expression, so of course nothing changed. This was a bit confusing. Of course I soon realized what happened, but it would be less confusing if my very first click of the Run button actually appeared to do something. I would go so far as to do something like highlighting the result with a yellow background that fades out over a second or two, to draw attention to the result. Maybe you'd just want this at the beginning and then stop doing the fading after a few clicks of the Run button, I'm not sure. But it would at least be helpful when getting familiar with the page.