I'm trying to change the color of a DIV Element that's assigned to the class about_title, with the condition of another div to have a display of "block", which id is about. This is my JS code:

   let about_title = document.getElementsByClassName("about_title") ;
   let about_content = document.getElementById("about") ;

   if (about_content.style.display == "block") {
       about_title.style.backgroundColor = "#ced2ff" ;
   } ;

It doesn't work and I can't get it done