seamless attribute for iframes

- UNOFF

The seamless attribute makes an iframe's contents actually part of a page, and adopts the styles from its hosting page. The attribute has been removed from both the WHATWG and the W3C HTML5 specifications.

IE

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

Edge

  1. 12 - 79: Not supported
  2. 80: Not supported

Firefox

  1. 2 - 71: Not supported
  2. 72: Not supported
  3. 73 - 74: Not supported

Chrome

  1. 4 - 19: Not supported
  2. 20 - 26: Disabled by default
  3. 27 - 79: Not supported
  4. 80: Not supported
  5. 81 - 83: Not supported

Safari

  1. 3.1 - 6.1: Not supported
  2. 7 - 7.1: Not supported
  3. 8 - 12.1: Not supported
  4. 13: Not supported
  5. TP: Not supported

Opera

  1. 9 - 65: Not supported
  2. 66: Not supported

iOS Safari

  1. 3.2 - 6.1: Not supported
  2. 7: Not supported
  3. 8 - 13.1: Not supported
  4. 13.2: Not supported
  5. 13.3: Not supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.4.4: Not supported
  2. 76: Not supported

Blackberry Browser

  1. 7: Not supported
  2. 10: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 46: Not supported

Chrome for Android

  1. 79: Not supported

Firefox for Android

  1. 68: Not supported

IE Mobile

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

UC Browser for Android

  1. 12.12: Not supported

Samsung Internet

  1. 4 - 9.2: Not supported
  2. 10.1: Not supported

QQ Browser

  1. 1.2: Not supported

Baidu Browser

  1. 7.12: Not supported

KaiOS Browser

  1. 2.5: Not supported

Chrome 20-26 had partial support behind a flag, though this was later removed.

Resources:
Article
Bug on Firefox support: wontfix
Experimental polyfill
Microsoft Edge Developer UserVoice: No plans