Gradient transparency results in full opacity for half of
Gradient transparency results in full opacity for half of,transparency - Gimp Color To Alpha removes too much opacity,画像をマウスオーバー時に半透明にする,シンプル実装!CSSのみでaタグ画像をマウスオーバーで半透明に,mark_rect opacity · Issue #1302 · vega/altair · GitHub