chromium/third_party/blink/web_tests/external/wpt/css/css-text-decor/text-shadow/basic-opacity-ref.html

<div style="position: absolute; top: 33px; left: 33px; color: rgba(0, 0, 255, 0.2); z-index: 0;">Hello</div>
<div style="position: absolute; top: 30px; left: 30px; color: green; z-index: 1;">Hello</div>