Adds support for percentage values to the opacity properties, specifically, opacity, stop-opacity, fill-opacity, stroke-opacity, and shape-image-threshold. For example, opacity: 50%; is equivalent to opacity: 0.5; https://drafts.csswg.org/css-color/#transparency
This brings consistency and spec compliance. The rgba() function already accepts percentage alpha value, for example rgba(0, 255, 0, 50%).
Specification currently under development in a Working Group
Status in Chromium
Enabled by default
Consensus & Standardization
Search tagsopacity, alpha-value,
Last updated on 2021-03-12