I want to change the background color of a class in fixtures class, but I don't know how to get the element (I am trying to change it from another file). How do I get the card element from page_edit.html.erb file, as shown below?

I want to change the background of(db>fixtures>page_template.rb ):

<div class="card" style="...">
  <div class="card-body py-3">
    ...
  </div>
</div>

where I change the color:( views>refarral>page_edit.html.erb)

$("#favcolor").on("change", function () {
  $(".card").css("background-color", $("#favcolor").val());
});