How to create WordPress theme support for Cyrillic?

the slider doesn’t view Cyrillic header from the blog.
how to fix it?

Thank you!

Strange that it works elsewhere but doesn’t work inside slider.

You can fix it by simply adding the following lines to the WordPress Dashboard → Theme Options → Other → Custom CSS

.featured-text .featured-title {
  font:  28px 'Helvetica', sans-serif;

Now it works well. Thank you!