Some css changes.

It wasn't obvious to me that the 'sample data button' was a button you could use to select the sample data so I added an underline to it to make that clearer. Likewise, the placeholder text in the text area looked like normal text so I made it slightly lighter in color.
Underlined all links but you can ignore that part if you want...I just thought that would help differentiate what's clickable from what isn't.