Can I use
?

system-ui value for font-family

- WD

Value for font-family that represents the default user interface font.

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 - 42: Not supported
  2. 43 - 80: Partial support
  3. 81: Partial support
  4. 82 - 83: Partial support

Chrome

  1. 4 - 52: Not supported
  2. 53 - 55: Partial support
  3. 56 - 85: Supported
  4. 86: Supported
  5. 87 - 89: Supported

Safari

  1. 3.1 - 8: Not supported
  2. 9: Support unknown
  3. 9.1 - 10.1: Partial support
  4. 11 - 13.1: Supported
  5. 14: Supported
  6. TP: Supported

Opera

  1. 9 - 42: Not supported
  2. 43 - 70: Supported
  3. 71: Supported

iOS Safari

  1. 3.2 - 8.4: Not supported
  2. 9 - 10.3: Partial support
  3. 11 - 13.7: Supported
  4. 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: Not supported

IE Mobile

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

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 5.4: Not supported
  2. 6.2 - 11.2: Supported
  3. 12.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Not supported

KaiOS Browser

  1. 2.5: Partial support
Resources:
Firefox support bug
MDN on the font-family property