Comments popup (Jetpack style) redesign

Hello!
There is the problem shortly:
I decided to use Jetpacks Comments module for displaying WP Comments popup form in my site. WP Jetpack allows to choose between the three color-scheme. I chose the dark one. It nearly suits to me, except the submit button — I want it desperately redesign using my themes style.css file. But that doesn’t work!
Is there some .css file in the jetpacks plugins directory, what I need to change?

(style names: #respond .form-submit input, #respond .form-submit input#comment-submit, #respond .comment-form-fields input[type=submit], #respond p.form-submit input[type=submit], #respond input[type=submit], #commentform #submit)