Hi there!
You could use CSS to adjust the color there. First, don’t edit the theme files directly, otherwise your changes will be overwritten every time the theme is updated to the latest version.
An easy way to add custom CSS is to install the Jetpack plugin and activate the Custom CSS module. Then go to Appearance > Edit CSS and paste it in there. (Alternatively, you could either install a standalone custom CSS plugin, or create a child theme.)
Once you have your CSS editor or child theme to add your CSS, try this:
#masthead, #masthead a {
background-color: #fff;
color: #000;
}
That will change the background color there to white (#fff) and the #000 makes the site title black, and can be changed to any color you’d like.
Let me know if you have any questions or it gives you any trouble. (Be sure to share a link to your site so I can check it out directly. I tested this CSS on the demo.)
