Looked into this a bit more - you're not actually using this theme - the one you have is here:
Since that's a commercial theme, I have no way to know if or what has been changed. The problem with changing theme files directly is that the changes will be lost when the theme is updated.
To avoid that, you can use a custom CSS option if your theme has it or add using a custom CSS plugin. For more than CSS changes we recommend a child theme -
So at this point, I'd suggest you use a custom CSS plugin if your theme doesn't have that option - and just add changes there.
For more detailed/informed help, you might want to check with the developer of the theme.