24 bit colour terminal background printing. Has some bugs: why the first line has no background... why it takes a few runs in a clean terminal before it prints new lines...?

main.rs

fn main() {
    let colours: &[[u16; 3]] = &[
        [204, 12, 56],
        [238, 15, 44],
        [255, 64, 32], 
        [255, 101, 39], 
        [254, 189, 56],
        [254, 242, 198]
    ];

    for colour in colours {
        use std::fmt::Write;
        
        let mut buf = String::new();
        let [r, g, b] = colour; 
        let bright = (r + g + b) > 384;
    
        let _ = write!(&mut buf, "\u{1b}[48;2;{r};{g};{b}m");
        if bright {
            let _ = write!(&mut buf, "\u{1b}[30m");
        }

        let _ = writeln!(&mut buf);
        let _ = writeln!(&mut buf);
        let _ = writeln!(&mut buf, "{colour:?}");

        print!("{buf}\u{1b}[0m");
    }
}