May i know which kind of button you referring to?

Is it possible for you provide us some of the screenshot or page URL so we can better have a look?

It would be all the buttons on the sidebar. See image. This would include "New Page", "New Group", "New Album", "New Poll"

You can change this styling from your site backend > Easysocial > setting > layout > styling , hope this will help.

That does not work... It keeps them gradient. Is there a custom CSS I can use?

You can try this.

body #es .es-sidebar .btn-es-primary,

body #es .btn-es-primary:hover, 

body #es .btn-es-primary:active, 

body #es .btn-es-primary:focus {

    background-color: #FFA500 !important;

}