What are the theme related controls I have access to?

You can switch the frontend between dark and white themes from the Theme menu under Settings.

Go to Settings > Theme Settings, select the Dark/Light theme, and click the save button.

Other than that, you can further drill-down and change different CSS level elements, like colors for background, title, text and so on from the CSS option under Settings.

“You have the option to specify the color using either its Hex Code or Color Name. For instance, the color name is White, and the hex code is #FFFFFF. You can include either one as needed.”