src/vs/editor/browser/services/abstractCodeEditorService.ts/DecorationCSSRules/getCSSTextForModelDecorationInlineClassName
class DecorationCSSRules:	private getCSSTextForModelDecorationInlineClassName(opts: IThemeDecorationRenderOptions | undefined): string {
		if (!opts) {
			return '';
		}
		const cssTextArr: string[] = [];
		this.collectCSSText(opts, ['fontStyle', 'fontWeight', 'textDecoration', 'cursor', 'color', 'opacity', 'letterSpacing'], cssTextArr);
		if (opts.letterSpacing) {
			this._hasLetterSpacing = true;
		}
		return cssTextArr.join('');
	}