Yoga is a great choice for layout here. In my own terminal-based projects, I was initially worried that there would be a mismatch between its intended use (pixel-based layout) and the chunkiness of character-based layout in terminal apps, but I was happily proven wrong. Yoga is a great choice for laying out terminal apps.

I wish there was as nice a library for cascading style sheets in terminal apps, but we can't have it all.