Hi Oliver.
This is definitely a mystery. I edited cforms.php to remove CSS styling:
// The code I edited:
$content .= $ntt . '<p class="cf-sb"><input type="submit" name="sendbutton'.$no.'" id="sendbutton'.$no.'" class="sendbutton" value="' . $cformsSettings['form'.$no]['cforms'.$no.'_submit_text'] . '"'.
$ajaxenabled.'/></p>';
And changed it several times. Ultimately I stripped out everything, and tried with the folliowing. Viewing the source code, there was no styling, but it's still taking on the styling from the stylesheet.
// WhatI I changed it to:
$content .= $ntt . '<input type="submit" value="' . $cformsSettings['form'.$no]['cforms'.$no.'_submit_text'] . '"'. $ajaxenabled.'/>';
// Sourceode results in this:
<input type="submit" value="Submit" onclick="return cforms_validate('3', false)"/>
I'm out of ideas!