Click button when it changes to Active

Im currently trying to find a solution for my problem, I have a website were orders come in and there is a button which turns blue and I need to click it to accept all orders.

The logic behind it, it's a button which stays grey all the time, when a order enters it turns blue and active, and needs to be pressed. It's website in the browser.

window.onload=function(){

  setInterval(autoClick,100);

}
function autoClick(){
  if(document.getElementsByClassName("accept").length>0){
  document.getElementsByClassName("accept")[0].click();
}
}

I've started this but don't know how it shoud detect if the button turns blue.

Thanks in advance!