“Leave a reply” text, and so much vertical spacing…how to remove?

Hello. I’d like to use Jetpack for comments as Livefyre is now kaput. However, putting the comment_form() function doesn’t quite do the job as there’s a giant “Leave a Reply” rubbish. Also, there’s massive vertical space above and below the tiny comment box. And because all this happens in an iframe, it’s hard to style — the button for “post comment” does not follow the theme at all.

The developer website of Jetpack is also silent on these issues.

Could I please get some guidance on:

1. How to remove the H3 with “Leave a Reply” etc? (I know I can hide it with CSS, but would rather not do all that. Having it in the body text )

2. How can I style the “post comment” button to follow the look of input[type=submit] of my theme, or even attach a class of .button to it?

3. How to remove the enormous spacing above and below the textbox. Even with the comment expanded, which shows the Notify subscribe checkboxes, it’s too much spacing. I tried the following, but this hasn’t helped either:

<style>
#respond, #respond  iframe, #respond  form { margin: 0; padding: 0 }
</style>