I have been tinkering with changing the color scheme of my site, and I think I have something that I can go live with. Rather than trust myself entirely with choosing colors, I decided to search around the web to find some color schemes I can use. I happened upon a cool interactive tool for generating color schemes, which is especially great because you can specify some colors you've already picked and have it generate colors complementary to those. Perhaps some day someone with a better aesthetic eye will point out flaws in this tool, but for now I'm going to run with what it gives me and experiment.
I also discovered CSS variables as I looked for an intelligent way to define colors only once and use them multiple times. Now that I have this set up, I can swap out color schemes at will, so the look of the site may be changing from time to time as I adjust.