Site CSS overrides Mailchimp CSS

Hi,

My site is temporarily here: http://b50.e16.myftpupload.com/

I have the Mailchimp widget in the footer and it looks great, but I need to change the color on the submit button. I have added

#mc_signup _button
{
color: #ffffff;
border-color: #ffffff;
}

to the CSS of my site, but I suspect the .button style from my theme is overriding everything. I’m not that experienced with CSS but I have managed thus far to customize quite a few elements, but now I’m stuck.

Can you help?

https://ww.wp.xz.cn/plugins/mailchimp/