CSS3 Box-shadow

- CR

Method of displaying an inner or outer shadow effect to elements

IE

  1. 5.5 - 8
  2. 9 - 10
  3. 11

Edge

  1. 12 - 81
  2. 83

Firefox

  1. 2 - 3
  2. 3.5 - 3.6
  3. 4 - 77
  4. 78
  5. 79 - 80

Chrome

  1. 4 - 9
  2. 10 - 81
  3. 83
  4. 84 - 86

Safari

  1. 3.1 - 4
  2. 5
  3. 5.1 - 13
  4. 13.1
  5. 14 - TP

Opera

  1. 9 - 10.1
  2. 10.5 - 68
  3. 69

iOS Safari

  1. 3.2
  2. 4 - 4.3
  3. 5 - 13.3
  4. 13.4
  5. 14.0

Opera Mini

  1. all

Android Browser

  1. 2.1 - 3
  2. 4 - 4.4.4
  3. 81

Blackberry Browser

  1. 7
  2. 10

Opera Mobile

  1. 10
  2. 11 - 12.1
  3. 46

Chrome for Android

  1. 81

Firefox for Android

  1. 68

IE Mobile

  1. 10
  2. 11

UC Browser for Android

  1. 12.12

Samsung Internet

  1. 4 - 11.2
  2. 12.0

QQ Browser

  1. 10.4

Baidu Browser

  1. 7.12

KaiOS Browser

  1. 2.5

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