this is not vaid markup:
<h1 p class="whatever">Title</p></h1>
valid markup would be:L
<h1><p class="whatever">Title</p></h1>
it sounds to me like the issue is in the style definition for the whatever class being applied to the span.
what if it's just a plan h1 tag:
<h1>Title</h1>
with no styling applied, does that look better, if so look int the setting for the whatever class.