Strange issue with checkbox - HTML5

This is on HTML5. Please check and run following HTML code. You will see that the check box leaves yellow padding that precedes the checkbox itself and also it leaves trailing yellow padding. Not sure which CSS property is causing this. I think the div ID "steps" and its CSS is causing the issue. But I must have those settings. How can I just show a normal looking checkbox? Please see the attached image of the issue.

HTML Code:

... HTML:

Strange issue with checkbox - HTML5

Poster :