How can I make the head of my code immovable?

Question

I tried creating a whatsapp clone but it didnt come out good.i'll post the code below you can check it out.
https://code.sololearn.com/W87m4w5BSuHi/?ref=app
https://code.sololearn.com/W87m4w5BSuHi/?ref=app

Answer 1

Yes

Answer 2

Ok I will check it rn

Answer 3

you want your header “WHATSAPP” to be fixed?

Answer 4

here is an example that may help https://www.w3schools.com/howto/howto_js_sticky_header.asp