I know that there is a varity of HTML5 debuggers (such as in Dreamweaver), a vareity of JavaScript (such as JSLint), and CSS debuggers (such as Firebug), but is there a sing
For stuff like this I just use the built in tools in Chrome, or Firebug in Firefox if you swing that way. This is very handy for debugging JS and CSS, not sure about HTML5 though.