Is it possible to (easily) change the colours on an Elbrus site that was built on one of the quick start templates?

I don't believe Elbrus has an easy way to do it other than editing the theme. You can change the sass file that is often called 'base sass styles' I can't remember if Elbrus has this. I suggest migrating your version to the latest version so you have access to site management tools. My team at Anchor Group normally tries to add easy drag and drop areas into this nice tool so you don't have to use a developer as much. I'd be happy to give you free access to some of our courses I built so you can see what it can do. If you do have Site Management Tools, there is a setting that lets you change the theme (basically it changes the base sass styles in the theme I mentioned)

Aha! Found it! Thank you!! And yes, I desperately want these guys to upgrade, but it's not in the budget at the moment.