Scroll bar thumb should better be transparent.

[Congyuwang]

309458197-65df4411-51d6-450a-8986-afbabb5cd799.mov

The scroll bar thumb covers the highlights of the scroll bar.

I think maybe it is better to give scrollbar_thumb.background and scrollbar.thumb.border an alpha value, such as:

https://github.com/catppuccin/zed/blob/066afb8ba5eeb867106080e8ca28c5431ffde3a8/themes/catppuccin.json#L51-L55

        "scrollbar_thumb.background": "#acb0be80",
        "scrollbar.thumb.hover_background": "#9ca0b0",
        "scrollbar.thumb.border": "#acb0be80",
        "scrollbar.track.background": "#eff1f5",
        "scrollbar.track.border": "#4c4f6912",

Related: zed-industries/zed#8705

[huacnlee]

Fixed