#rrggbbaa hex color notation

- UNOFF

The CSS Color Module Level 4 defines new 4 & 8 character hex notation for color to include the opacity level.

IE

  1. 5.5 - 10: Not supported
  2. 11: Not supported

Edge

  1. 12 - 18: Not supported
  2. 79 - 85: Supported
  3. 86: Supported

Firefox

  1. 2 - 48: Not supported
  2. 49 - 80: Supported
  3. 81: Supported
  4. 82 - 83: Supported

Chrome

  1. 4 - 51: Not supported
  2. 52 - 61: Disabled by default
  3. 62 - 85: Supported
  4. 86: Supported
  5. 87 - 89: Supported

Safari

  1. 3.1 - 9.1: Not supported
  2. 10 - 13.1: Supported
  3. 14: Supported
  4. TP: Supported

Opera

  1. 9 - 38: Not supported
  2. 39 - 51: Disabled by default
  3. 52 - 70: Supported
  4. 71: Supported

iOS Safari

  1. 3.2 - 9.3: Not supported
  2. 10 - 13.7: Supported
  3. 14: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.4.4: Not supported
  2. 81: Supported

Blackberry Browser

  1. 7: Not supported
  2. 10: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 59: Supported

Chrome for Android

  1. 85: Supported

Firefox for Android

  1. 79: Supported

IE Mobile

  1. 10: Not supported
  2. 11: Not supported

UC Browser for Android

  1. 12.12: Not supported

Samsung Internet

  1. 4: Not supported
  2. 5 - 7.4: Disabled by default
  3. 8.2 - 11.2: Supported
  4. 12.0: Supported

QQ Browser

  1. 10.4: Not supported

Baidu Browser

  1. 7.12: Disabled by default

KaiOS Browser

  1. 2.5: Not supported

Only supported in Android WebViews in apps that target Android Pie, due to this issue

Resources:
JS Bin testcase
Edge support request for rrggbbaa