src/vs/platform/theme/browser/defaultStyles.ts/getButtonStyles
export function getButtonStyles(override: IStyleOverride<IButtonStyles>): IButtonStyles {
	return {
		buttonForeground: asCssValue(override.buttonForeground ?? buttonForeground),
		buttonSeparator: asCssValue(override.buttonSeparator ?? buttonSeparator),
		buttonBackground: asCssValue(override.buttonBackground ?? buttonBackground),
		buttonHoverBackground: asCssValue(override.buttonHoverBackground ?? buttonHoverBackground),
		buttonSecondaryForeground: asCssValue(override.buttonSecondaryForeground ?? buttonSecondaryForeground),
		buttonSecondaryBackground: asCssValue(override.buttonSecondaryBackground ?? buttonSecondaryBackground),
		buttonSecondaryHoverBackground: asCssValue(override.buttonSecondaryHoverBackground ?? buttonSecondaryHoverBackground),
		buttonBorder: asCssValue(override.buttonBorder ?? buttonBorder),
	};
}