Haha.. thanks. I was trying to work out where you got the nice formatting.
I'll try and move my css into a <style> block. I also found moving to the 'plain' theme (rather than the 'simple' theme) makes the custom CSS work a lot better - I guess there is none being applied by default.
Suddenly, the button code is working without !important.
I truly appreciate the guidance!
If you want control over all styles, you should use this: MktoForms2 :; Destyle Marketo Form