Inquire Stylesheet for changing background color of specific letter?


I am using the inquire crate, specifically Text for accepting text from the user.

Let's say hypothetically I want to make all the letter "a" characters of the prompt text have teal background... I can see Text has a RenderConfig field which has a "prompt" Stylesheet, but a "Stylesheet" in this case is just this simple struct...

pub struct StyleSheet {
    pub fg: Option<Color>,
    pub bg: Option<Color>,
    pub att: Attributes,

How can I incorporate fancy logic in my stylesheet for only making letter "a" characters the special color?