Help with CSS!

Hi!

I purchased a theme and CANNOT change the CSS (I just want to change font color!) The author of the theme is NOT helping. This is what I have in the .CSS file….

Suggestions on how to change formatting?

Version: 1
License: Single commercial license
License URI: license.txt
Tags: dark, light, white, black, gray, one-column, two-columns, left-sidebar, right-sidebar, fixed-width, flexible-width, custom-background, custom-colors, custom-header, custom-menu, editor-style, featured-image-header, featured-images, full-width-template, microformats, post-formats, rtl-language-support, sticky-post, theme-options, translation-ready
*/

@import ‘css/reset.css’;
@import ‘css/style.css’;
@import ‘css/grid-persent.css’;
.sticky {};
.bypostauthor{}