Weird behavior of theme changing icon

**Describe the bug**
The icon of the theme-changing icon is not working properly

**Expected behavior**
its size should not be changed while changing the theme of the website

**Screenshots**


**Desktop (please complete the following information):**
- OS: [window]
- Browser [Brave and Chrome]
- Version [e.g. 22]

**Smartphone (please complete the following information):**
- Device: [Oppo a52]
- OS: [e.g. iOS8.1]
- Browser [Brave and Chrome]
- Version [e.g. 22]

**Additional context**
Add any other context about the problem here.