CSSWG added the following resolution(s): RESOLVED: transparent colors in the thumb are transparent towards the track, and transparent colors in the track are transparent towards the background; ...
However, this causes problems for icons and similar things that are meant to be semi-transparent above the background. Also, doesn't account for other things like background-image. Consider this ...
一部の結果でアクセス不可の可能性があるため、非表示になっています。
アクセス不可の結果を表示する