Function parse_border_width_term 

pub fn parse_border_width_term(
    ctx: &str,
    name: &str,
    value: &str,
    s: &str,
) -> Result<f32, ParseError>

CSS border-width keyword / length term: thin (1px), medium (3px), thick (5px), or a px length. Percent is not valid CSS for border widths and is rejected.