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CSS3 Border-radius (rounded corners)

- CR

Method of making the border corners round. Covers support for the shorthand border-radius as well as the long-hand properties (e.g. border-top-left-radius)

Chrome

  1. ✅ 4: Supported
  2. ✅ 5 - 142: Supported
  3. ✅ 143: Supported
  4. ✅ 144 - 146: Supported

Edge

  1. ✅ 12 - 142: Supported
  2. ✅ 143: Supported

Safari

  1. ✅ 3.1 - 4: Supported
  2. ✅ 5: Supported
  3. ✅ 5.1 - 6.1: Supported
  4. ✅ 7 - 26.1: Supported
  5. ✅ 26.2: Supported
  6. ✅ TP: Supported

Firefox

  1. ◐ 2: Partial support
  2. ✅ 3 - 3.6: Supported
  3. ✅ 4 - 49: Supported
  4. ✅ 50 - 144: Supported
  5. ✅ 145: Supported
  6. ✅ 146 - 148: Supported

Opera

  1. ❌ 9 - 10.1: Not supported
  2. ✅ 10.5 - 121: Supported
  3. ✅ 122: Supported

IE

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

Chrome for Android

  1. ✅ 142: Supported

Safari on iOS

  1. ✅ 3.2: Supported
  2. ✅ 4 - 18.7: Supported
  3. ✅ 26.0: Supported
  4. ✅ 26.1: Supported

Samsung Internet

  1. ✅ 4 - 28: Supported
  2. ✅ 29: Supported

Opera Mini

  1. ❌ all: Not supported

Opera Mobile

  1. ❌ 10: Not supported
  2. ✅ 11 - 12.1: Supported
  3. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ✅ 2.1: Supported
  2. ✅ 2.2 - 4.4.4: Supported
  3. ✅ 142: Supported

Firefox for Android

  1. ✅ 144: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ✅ 3: Supported
Resources:
Polyfill which includes border-radius
Border-radius CSS Generator
MDN Web Docs - CSS border-radius
Detailed compliance table
WebPlatform Docs