自定义轴标题渲染

In order to make 2-axis (opposite axis) charts a bit more readable than this https://jsfiddle.net/tah74jm4/ (which line belongs to which label?), the designer wanted a color indication on the label for each line. I know there are legends, however that takes up additional space and is also not very flexible in positioning the legend items. In this case, a legend next to each label would better indicate which values belong to which line.