CSS Generated content for pseudo-elements

- REC

Method of displaying text or images before or after the given element's contents using the ::before and ::after pseudo-elements. All browsers with support also support the attr() notation in the content property.

Chrome

  1. 4 - 125: Supported
  2. 126: Supported
  3. 127 - 129: Supported

Edge

  1. 12 - 125: Supported
  2. 126: Supported

Safari

  1. 3.1 - 17.4: Supported
  2. 17.5: Supported
  3. 17.6 - TP: Supported

Firefox

  1. 2 - 127: Supported
  2. 128: Supported
  3. 129 - 131: Supported

Opera

  1. 9 - 110: Supported
  2. 111: Supported

IE

  1. 5.5 - 7: Not supported
  2. 8: Partial support
  3. 9 - 10: Supported
  4. 11: Supported

Chrome for Android

  1. 126: Supported

Safari on iOS

  1. 3.2 - 17.4: Supported
  2. 17.5: Supported
  3. 17.6 - 18.0: Supported

Samsung Internet

  1. 4 - 24: Supported
  2. 25: Supported

Opera Mini

  1. all: Supported

Opera Mobile

  1. 10 - 12.1: Supported
  2. 80: Supported

UC Browser for Android

  1. 15.5: Supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 126: Supported

Firefox for Android

  1. 127: Supported

QQ Browser

  1. 14.9: Supported

Baidu Browser

  1. 13.52: Supported

KaiOS Browser

  1. 2.5: Supported
  2. 3: Supported

For content to appear in pseudo-elements, the content property must be set (but may be an empty string).

Resources:
Dev.Opera article
WebPlatform Docs
Guide on usage