Increase Length of Basemap Transparency Slider Bar when More Basemaps Added to Group

GVH 2.10  To improve usability of the basemaps transparency slider group, it would be great if the slider bar's length increased in length as more basemaps are added to it. We  have about 10 different years of imagery (with more coming in the future), however, the slider bar is the same size whether there are four basmaps or 12 in the slider group. As more basemaps are added, the spacing between the basemaps slider "lines" decreases, making it difficult for the user to easily transition between basemaps.
I know extending the slider group bar in the viewer for the tablet and handheld viewers may not be advantageous due to the limited space, so maybe only include this on the desktop configuration.