sorry if this is too simple a question, @sbatuev, but in what css file is the new button style to be put? I've tried:

/wp-content/themse/arras-theme/css/styles/default.css
/wp-content/themse/arras-theme/css/mycss.css (the stylesheet particular to the site)

So far, no dice. & just to be thorough, I have referenced the new style in the settings page for the form to:

[submit class:SignUpForEmailSubmitButton " "]

- O8