font sizes.swift

    private var titleAttributes: AnyPublisher<[NSAttributedString.Key: Any], Never> {
        appearance.textSizeAdjustmentPublisher
            .combineLatest(isRead)
            .map { textSizeAdjustment, isRead -> [NSAttributedString.Key: Any] in
                [
                    .font: UIFont.scaledSystemFont(
                        style: .title2,
                        relativeSize: textSizeAdjustment,
                        weight: .medium
                    ),
                    .foregroundColor: isRead ? UIColor.secondaryLabel : UIColor.label,
                ]
            }
            .eraseToAnyPublisher()
    }

extension UIFont {
    static func scaledSystemFont(
        style textStyle: UIFont.TextStyle,
        relativeSize: CGFloat,
        weight: UIFont.Weight = .regular
    ) -> UIFont {
        let font = UIFont.systemFont(
            ofSize: UIFont.systemFontSize + relativeSize,
            weight: weight
        )
        return UIFontMetrics(forTextStyle: textStyle)
            .scaledFont(for: font)
    }
}