Can I use
?

CSS position:fixed

- REC

Method of keeping an element in a fixed location regardless of scroll position

Chrome

  1. ✅ 4 - 135: Supported
  2. ✅ 136: Supported
  3. ✅ 137 - 139: Supported

Edge

  1. ✅ 12 - 135: Supported
  2. ✅ 136: Supported

Safari

  1. ✅ 3.1 - 9: Supported
  2. ✅ 9.1: Supported
  3. ✅ 10 - 18.4: Supported
  4. ✅ 18.5: Supported
  5. ✅ TP: Supported

Firefox

  1. ✅ 2 - 137: Supported
  2. ✅ 138: Supported
  3. ✅ 139 - 141: Supported

Opera

  1. ✅ 9 - 116: Supported
  2. ✅ 117: Supported

IE

  1. ❌ 5.5: Not supported
  2. ❌ 6: Not supported (but has polyfill available)
  3. ✅ 7 - 10: Supported
  4. ✅ 11: Supported

Chrome for Android

  1. ✅ 136: Supported

Safari on iOS

  1. ❌ 3.2 - 4.3: Not supported
  2. ◐ 5 - 7.1: Partial support
  3. ✅ 8 - 18.4: Supported
  4. ✅ 18.5: Supported

Samsung Internet

  1. ✅ 4 - 26: Supported
  2. ✅ 27: Supported

Opera Mini

  1. ❌ all: Not supported

Opera Mobile

  1. ✅ 10 - 12.1: Supported
  2. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ◐ 2.1 - 2.3: Partial support
  2. ✅ 3: Supported
  3. ✅ 4 - 4.3: Supported
  4. ✅ 4.4 - 4.4.4: Supported
  5. ✅ 136: Supported

Firefox for Android

  1. ✅ 137: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ✅ 3: Supported
Resources:
Article on mobile support
position: fixed on MDN