Can I use
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Scoped attribute

- UNOFF

Deprecated method of allowing scoped CSS styles using a "scoped" attribute. Now removed from the specification and replaced by the @scope CSS rule.

Chrome

  1. ❌ 4 - 19: Not supported
  2. ❌ 20 - 36: Disabled by default
  3. ❌ 37 - 147: Not supported
  4. ❌ 148: Not supported
  5. ❌ 149 - 151: Not supported

Edge

  1. ❌ 12 - 146: Not supported
  2. ❌ 147: Not supported

Safari

  1. ❌ 3.1 - 26.3: Not supported
  2. ❌ 26.4: Not supported
  3. ❌ 26.5 - TP: Not supported

Firefox

  1. ❌ 2 - 20: Not supported
  2. ✅ 21 - 54: Supported
  3. ❌ 55 - 60: Disabled by default
  4. ❌ 61 - 149: Not supported
  5. ❌ 150: Not supported
  6. ❌ 151 - 153: Not supported

Opera

  1. ❌ 9 - 127: Not supported
  2. ❌ 131: Not supported

IE

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

Chrome for Android

  1. ❌ 147: Not supported

Safari on iOS

  1. ❌ 3.2 - 26.3: Not supported
  2. ❌ 26.4: Not supported
  3. ❌ 26.5: Not supported

Samsung Internet

  1. ❌ 4 - 28: Not supported
  2. ❌ 29: Not supported

Opera Mini

  1. ❌ all: Not supported

Opera Mobile

  1. ❌ 10 - 12.1: Not supported
  2. ❌ 80: Not supported

UC Browser for Android

  1. ❌ 15.5: Not supported

Android Browser

  1. ❌ 2.1 - 4.4.4: Not supported
  2. ❌ 147: Not supported

Firefox for Android

  1. ❌ 150: Not supported

QQ Browser

  1. ❌ 14.9: Not supported

Baidu Browser

  1. ❌ 13.52: Not supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ❌ 3: Not supported
Resources:
Firefox bug #1291515: disable `<style scoped>` in content documents
HTML5Rocks article
Polyfill
HTML5 Doctor article