Highend Theme Button Styling

Hi;
where can I style the default buttons on highend them such as the one on the pre-footer (for example “CALL US!” button here : http://www.welkinwebgroup.com/about-us/) or the contact form (for instance “SEND MESSAGE” here : http://www.welkinwebgroup.com/contact-us/)

See the attached image please (It did not allow me to upload the second image for the contact, but there is only one button on the page I mentioned the URL for).

Specifically I need to change the color of the button and the hover state of the button.

Thanks for your time!
Marcus