So I have two position absolute here where is front and back in the html function in so front is what will happen in the front of animation and as you can see there is like a small button there that looks like a movie icon. So when it click the back className supposed to popup after the animation of front but it doesn't work properly..Here is the CODEPEN

Normally...I know this is simple but sometimes I always lost..So basically all my question here is how can I popup it up? IT is display:"none" for initial when it is not clicking yet the button and it will become display:"flex" whenever the button was click. I hope this is clear and proper. Thanks for the hlep.