Which css code for blog posts.

Hi,

I want to change the width of an email input field.
Which selector do I need to use to have it directed only to the blog posts?

the css I want to apply is this one:

#emaillijst-vertrekken-1 > label.EMAIL-label.yikes-mailchimp-field-required { width: 70%;}

This is a note in a widget that appears at the end of each blog post. The point is that this same form comes back in some other places. That's why the need to define it only to the blog posts.

Thanks

http://succesvolsamenwerken.nl/winwin-maar-wel-op-mijn-manier/