Custom CSS for Wordpress

I need two custom requirements added to a wordpress website. The site is built with Meks Megaphone theme. I am looking to change the colour of the tags, and the colour of the built-in audio player. The only options to do this within the theme customization involve changing whole groups of colors across the site, which I do not wish to do. I have been trying unsuccessfully to do this myself with custom css. (I need a solution that won't be overwritten when the theme updates.)