Text on “Reply” buttons invisible when general color is other than Gold

When Customize | General Colors | General Color Skin is set to Gold, the “Reply” button text in a blog post page is visible. But when the color is set to Blue, Green, or Red, the “Reply” button text is not visible. In the sample page link, I have set the general color skin in the theme to Blue, and you can see that the “Reply” buttons on each post and comment don’t show any text…just a blue button with no text on it.

I have tried viewing the page in Chrome, IE 11, Firefox, with the same results.

I would like to use Blue instead of Gold, so I attempted to work around the issue by adding CSS to color the text in .comment-reply-link, but doing this had no effect.

Is there something I can do in Customize | Additional CSS that would cause the button text to show up when the general color skin is set to Blue? Or is there something in the theme itself that I can adjust to work around this issue?

I like your theme very much. I am new to WordPress, so please forgive me if I don’t use the correct terminology yet.

The page I need help with: [log in to see the link]