In the html for the forms there is an empty tag: <p class="ckCSSclear" /> between eacht two fields. Although this is legal XML it seems that in an XHTML doctype it is not interpreted as a complete <p> tag by at least Firefox an Chromium browsers (I have not tested other ones). This leads to these browsers viewing everything between two of these tags as being part of the preceding <p> tag, at least when using an XHTML doctype.
If there is no specific reason against it, the fix is to change line 408 in com_ckforms/views/ckforms/tmpl/default.php from:
<p class="ckCSSclear" />
to:
<p class="ckCSSclear"></p>
This of course simply closes the <p> tag allowing for more specific css styling.
Regards,
Huub