You may need to modify the index.html file to center it. Open that file and look for something like:
<div id="c2canvasdiv" style="width: 538px; height: 349px; margin-left: 242px; margin-top: 0px;">
That div contains your game. You may need to change the margin-top:0px to something like margin-top:200px.
This is a static solutions, it will leave a space of 200 pixels on the top. To really center divs, you should take a look at google for the keywords: html vertical align.
Tell me if it helps!
Thanks alot! This is exactly what I was looking for!
Just some info for people who might look for the same thing:
Exported index.html contains:
<div id="c2canvasdiv" style="margin: 0 auto; width: *your project width*px; height: *your project width*px;">
Just add margin-top: *size you want*px; somewhere in this brakets.