How can I make the buttons turn red when it reaches the specified number?

Question

I have this code that simply adds and subtracts. I recently figured out how to limit it. But how can I make the buttons turn red?

Like
When it reaches 5, the + button will turn red
and when it reaches 1, the - button will turn red
https://code.sololearn.com/WQtkfnr8ukt3/?ref=app

Answer 1

https://code.sololearn.com/WRfeno89lFhL/?ref=app

Answer 2

Donna I was told to do that so that it stop counting. I want it to stop counting and turn red but only when it reaches the specified number.

Answer 3

Everything I've tried has failed ;-;