[Make]: Editing Navigation Menu

I am using the free version of Make theme, by Theme Foundry.

I would like to make the drop-down menu indicator (down arrow) in the navigation menu more obvious, preferably by making it bold and enlarging it.

Can anyone tell me how to accomplish this, perhaps by inserting some custom CSS, but not by altering the theme code, as I am not a coder.

Thank you in advance!