Can I use
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: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 - 134: Supported
  3. ✅ 135: Supported
  4. ✅ 136 - 138: Supported

Edge

  1. ✅ 12 - 134: Supported
  2. ✅ 135: Supported

Safari

  1. ❌ 3.1 - 4: Not supported
  2. ✅ 5 - 18.3: Supported
  3. ✅ 18.4: Supported
  4. ✅ 18.5 - TP: Supported

Firefox

  1. ❌ 2 - 3.6: Not supported
  2. ✅ 4 - 136: Supported
  3. ✅ 137: Supported
  4. ✅ 138 - 140: Supported

Opera

  1. ﹖ 9 - 9.6: Support unknown
  2. ◐ 10 - 12.1: Partial support
  3. ✅ 15 - 116: Supported
  4. ✅ 117: Supported

IE

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

Chrome for Android

  1. ✅ 135: Supported

Safari on iOS

  1. ❌ 3.2 - 4.3: Not supported
  2. ✅ 5 - 18.3: Supported
  3. ✅ 18.4: Supported
  4. ✅ 18.5: Supported

Samsung Internet

  1. ✅ 4 - 26: Supported
  2. ✅ 27: Supported

Opera Mini

  1. ◐ all: Partial support

Opera Mobile

  1. ◐ 10 - 12.1: Partial support
  2. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ﹖ 2.1 - 2.2: Support unknown
  2. ✅ 2.3 - 4.4.4: Supported
  3. ✅ 135: Supported

Firefox for Android

  1. ✅ 137: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

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