Support media query feature `prefers-reduced-transparency`

[czerkies]

• https://www.w3.org/TR/mediaqueries-5/#prefers-reduced-transparency
• https://developer.chrome.com/blog/css-prefers-reduced-transparency/

Non-opaque interfaces can cause headaches or be a visual struggle for various types of vision deficiencies. This is why Windows, macOS and iOS have system preferences that can reduce or remove transparency from the UI.

[czerkies]

• Can be combined with @media (prefers-contrast: more)
• https://drafts.csswg.org/mediaqueries/#mq-list

[czerkies]

Use of subtractive strategy due to the lack of web browsers support. New issue to followup the browsers integration: #167