Can I use
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Shadow DOM (V1)

- WD

Method of establishing and maintaining functional boundaries between DOM trees and how these trees interact with each other within a document, thus enabling better functional encapsulation within the DOM & CSS.

Chrome

  1. 4 - 52: Not supported
  2. 53 - 116: Supported
  3. 117: Supported
  4. 118 - 120: Supported

Edge

  1. 12 - 18: Not supported
  2. 79 - 116: Supported
  3. 117: Supported

Safari

  1. 3.1 - 9.1: Not supported
  2. 10 - 16.5: Supported
  3. 16.6: Supported
  4. 17.0 - TP: Supported

Firefox

  1. 2 - 57: Not supported
  2. 58: Disabled by default
  3. 59 - 62: Disabled by default
  4. 63 - 116: Supported
  5. 117: Supported
  6. 118 - 120: Supported

Opera

  1. 9 - 39: Not supported
  2. 40 - 101: Supported
  3. 102: Supported

IE

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

Chrome for Android

  1. 117: Supported

Safari on iOS

  1. 3.2 - 9.3: Not supported
  2. 10 - 10.3: Partial support
  3. 11 - 16.6: Supported
  4. 17.0: Supported
  5. 17.1: Supported

Samsung Internet

  1. 4: Not supported
  2. 5: Partial support
  3. 6.2 - 21: Supported
  4. 22: Supported

Opera Mini

  1. all: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 73: Supported

UC Browser for Android

  1. 15.5: Supported

Android Browser

  1. 2.1 - 4.4.4: Not supported
  2. 117: Supported

Firefox for Android

  1. 117: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Supported

KaiOS Browser

  1. 2.5: Not supported
  2. 3: Supported
Resources:
Safari implementation bug
Firefox implementation bug
Google Developers - Shadow DOM v1: self-contained web components