I want to set zIndex to the first object b to 1 to display it in front. thanks you.

Question

Z-index to 1 to object b.
https://code.sololearn.com/WG3UVX6HctP1/?ref=app

Answer 1

Unfortunatelly you make quite many basic mistaces, such as ie. declaring of the same variable more than one time etc. I would like to recommend you repeating the JavaScript, HTML & CSS course as well as analyzing a few codes from SL Playground.
When you like you cann immediatelly start with this code:

https://code.sololearn.com/W8NO1CoHDo2y/?ref=app