background has unexpected offset when drawing text in an epaint::text::LayoutJob

[doy]

i have a simple program that demonstrates my issue here:

use eframe::egui;
use egui::epaint;

const FONT: &str = "Fira Mono";

const WHITE: epaint::Color32 = epaint::Color32::from_rgb(255, 255, 255);
const BLACK: epaint::Color32 = epaint::Color32::from_rgb(0, 0, 0);
const RED: epaint::Color32 = epaint::Color32::from_rgb(255, 0, 0);

struct Bgcolor {}

impl Bgcolor {
    fn new(ctx: &egui::Context) -> Self {
        let fc = fontconfig::Fontconfig::new().unwrap();
        let font = fc.find(FONT, None).unwrap();
        let font_data = std::fs::read(font.path).unwrap();

        let mut fonts = egui::FontDefinitions::default();
        fonts.font_data.insert(
            FONT.to_owned(),
            std::sync::Arc::new(egui::FontData::from_owned(font_data)),
        );
        fonts
            .families
            .entry(egui::FontFamily::Name(FONT.into()))
            .or_default()
            .insert(0, FONT.to_owned());

        ctx.set_fonts(fonts);

        Self {}
    }
}

impl eframe::App for Bgcolor {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        let frame_style = egui::Frame::central_panel(&egui::Style::default());
        egui::CentralPanel::default()
            .frame(frame_style)
            .show(ctx, |ui| {
                let font_id = epaint::FontId::new(
                    14.0,
                    egui::FontFamily::Name(FONT.into()),
                );
                let format = epaint::text::TextFormat {
                    font_id: font_id.clone(),
                    color: WHITE,
                    background: BLACK,
                    ..Default::default()
                };
                let inverse_format = epaint::text::TextFormat {
                    font_id,
                    color: RED,
                    background: WHITE,
                    ..Default::default()
                };

                let mut job = epaint::text::LayoutJob::default();
                job.append("   \n ", 0.0, format.clone());
                job.append("A", 0.0, inverse_format.clone());
                job.append(" \n   ", 0.0, format.clone());

                let galley = ui.fonts(|f| f.layout_job(job));
                let pos = ui.cursor().min;
                let (_, painter) = ui.allocate_painter(
                    galley.rect.size(),
                    egui::Sense::hover(),
                );
                painter.galley(pos, galley, BLACK);
            });
    }
}

fn main() {
    eframe::run_native(
        "bgcolor",
        eframe::NativeOptions::default(),
        Box::new(|cc| Ok(Box::new(Bgcolor::new(&cc.egui_ctx)))),
    )
    .unwrap();
}

this produces a window that looks like this:

you can see that the white background is slightly offset from the text within it (like, the rightmost few pixels of the A stick out past to the right, and you can see that the white box is closer to the left side than the right side of the overall black rectangle). am i doing something wrong here? how can i adjust for this? this seems to happen regardless of what font i choose.