How sololearn app is designed??

Question

I am a beginner and great fan of sololearn, i learnt much more here even being a chemist. i want to know which language is used to design its particularly its pages as definitions popup etc. is it java, HTML or any else? is it possible in any GUI framework of python?

Answer 1

it might as well be written with react native

Answer 2

Web pages are designed in HTML CSS and Javascript.
Android apps are designed in XML and Java.
IOS apps use swift (and I think XML)