Bashish is a theme-engine using bash and other POSIX shells to customize nearly all aspects of the terminal: title, colors, prompt, font, background, etc. It has a modular design which makes it easy to add features (and it does have a lot) while keeping good performance.
Never use this tool. Themes provided are last year. I’ll stick to simple code like:
export PS1="\[\033[0;30m\]\[\033[47m\][\u@\h:\w]\[\033[0m\]$ "