Ability to apply custom CSS

[propeeves]

I'd love to be able to apply extremely basic CSS like so:

h3 {
     font-size: Xpt;
     color: black;
}

b {
    font-weight: bolder;
}

p {
    font-family: sans-serif;
} 

Even if it involved dropping a .css page in the database folder, or going through a config file if that works with the current codebase better, it seems like a simple but powerful way to handle customization without using time/energy on UI for it!