HTML compatibility issues between 6.1 and 6.2

I've the following code which is working perfectly fine with Splunk 6.1: But when I moved this to Splunk 6.2, I'm not able to see the "Panel Title". It just flashes for a moment when the page loads and then goes away. If I use <h> tags instead of <div> under class="panel-head", then I'm able to see that. So can anybody explain me this behavior? Thanks in advance!!