CSS3 Box-shadow

- CR

Method of displaying an inner or outer shadow effect to elements

IE

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

Edge

  1. 12 - 88: Supported
  2. 89: Supported

Firefox

  1. 2 - 3: Not supported
  2. 3.5 - 3.6: Supported
  3. 4 - 86: Supported
  4. 87: Supported
  5. 88 - 89: Supported

Chrome

  1. 4 - 9: Supported
  2. 10 - 88: Supported
  3. 89: Supported
  4. 90 - 92: Supported

Safari

  1. 3.1 - 4: Partial support
  2. 5: Supported
  3. 5.1 - 13.1: Supported
  4. 14: Supported
  5. TP: Supported

Opera

  1. 9 - 10.1: Not supported
  2. 10.5 - 72: Supported
  3. 73: Supported

Safari on iOS

  1. 3.2: Partial support
  2. 4 - 4.3: Supported
  3. 5 - 13.7: Supported
  4. 14: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 3: Partial support
  2. 4 - 4.4.4: Supported
  3. 89: Supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 12.1: Supported
  3. 62: Supported

Chrome for Android

  1. 89: Supported

Firefox for Android

  1. 86: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 12.0: Supported
  2. 13.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported

Can be partially emulated in older IE versions using the non-standard "shadow" filter.

Resources:
Demo of various effects
Live editor
MDN Web Docs - box-shadow
WebPlatform Docs