Background-attachment: fixed; not work on smartphone

Question

https://code.sololearn.com/WeWh1vUsI2SU/#html

How to make it work on smartphone? I use background-attachment: fixed; to make parallax effect.

Answer 1

try -webkit-background-attachment : fixed; or other vendor prefixes if you're sure that your code is correct but doesn't work...

Answer 2

tried use it, work for some and not for some. -webkit- and -moz-