W3C validation

Question

 my site does not "validate", yet it works across every major browsers, does not produce errors in those browsers and looks correct in all browsers.

This is an example of an error I get

Error Line 38, Column 28: document type does not allow element "h3" here

var $jsuccessmessage = "<h3>We will be in contact soon. </h3>"; // success mess…

The element named above was found in a context where it is not allowed. This
could mean that you have incorrectly nested elements -- such as a "style"
element in the "body" section instead of inside "head" -- or two elements
that overlap (which is not allowed).

So I ask, how important is it that I correct these errors and do my best to produce fully validated code?

Answer 1

You should use W3C conventions as much as possible and these convention are going to be the most cross-browser compatible. That being said not all browsers implement W3C standards properly or completely. You will find that you have to break compliance to adjust for these quirks. It is not as bad as it used be, as the main culprit, Internet Explorer has been more accepting of standards.