Can I use
?

:optional CSS pseudo-class

- WD

The :optional pseudo-class matches form inputs (<input>, <textarea>, <select>) which are not :required.

Chrome

  1. 4 - 14: Support unknown
  2. 15 - 110: Supported
  3. 111: Supported
  4. 112 - 114: Supported

Edge

  1. 12 - 110: Supported
  2. 111: Supported

Safari

  1. 3.1 - 4: Not supported
  2. 5 - 16.2: Supported
  3. 16.3: Supported
  4. 16.4 - TP: Supported

Firefox

  1. 2 - 3.6: Not supported
  2. 4 - 110: Supported
  3. 111: Supported
  4. 112 - 113: Supported

Opera

  1. 9 - 9.6: Support unknown
  2. 10 - 12.1: Partial support
  3. 15 - 94: Supported
  4. 95: Supported

IE

  1. 5.5 - 9: Not supported
  2. 10: Supported
  3. 11: Supported

Chrome for Android

  1. 111: Supported

Safari on iOS

  1. 3.2 - 4.3: Not supported
  2. 5 - 16.2: Supported
  3. 16.3: Supported
  4. 16.4: Supported

Samsung Internet

  1. 4 - 19.0: Supported
  2. 20: Supported

Opera Mini

  1. all: Partial support

Opera Mobile

  1. 10 - 12.1: Partial support
  2. 73: Supported

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 2.2: Support unknown
  2. 2.3 - 4.4.4: Supported
  3. 111: Supported

Firefox for Android

  1. 110: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Supported

KaiOS Browser

  1. 2.5: Supported
  2. 3: Supported
Resources:
MDN Web Docs - CSS :optional
HTML specification for `:optional`
JS Bin testcase