Can I use
?

getComputedStyle

- REC

API to get the current computed CSS styles applied to an element. This may be the current value applied by an animation or as set by a stylesheet.

IE

  1. 5.5 - 8: Not supported
  2. 9 - 10: Supported
  3. 11: Supported

Edge

  1. 12 - 84: Supported
  2. 85: Supported

Firefox

  1. 2: Not supported
  2. 3 - 3.6: Partial support
  3. 4 - 79: Supported
  4. 80: Supported
  5. 81 - 82: Supported

Chrome

  1. 4 - 10: Partial support
  2. 11 - 84: Supported
  3. 85: Supported
  4. 86 - 88: Supported

Safari

  1. 3.1 - 4: Partial support
  2. 5 - 13.1: Supported
  3. 14: Supported
  4. TP: Supported

Opera

  1. 9 - 10.5: Partial support
  2. 10.6 - 69: Supported
  3. 70: Supported

iOS Safari

  1. 3.2 - 4.3: Partial support
  2. 5 - 13.7: Supported
  3. 14.0: Supported

Opera Mini

  1. all: Partial support

Android Browser

  1. 2.1 - 3: Partial support
  2. 4 - 4.4.4: Supported
  3. 81: Supported

Blackberry Browser

  1. 7: Partial support
  2. 10: Supported

Opera Mobile

  1. 10: Partial support
  2. 11 - 12.1: Supported
  3. 46: Supported

Chrome for Android

  1. 85: Supported

Firefox for Android

  1. 79: Supported

IE Mobile

  1. 10: Supported
  2. 11: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 11.2: Supported
  2. 12.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported
Resources:
Polyfill for IE
MDN Web Docs - getComputedStyle
Demo
WebPlatform Docs