Markdown Accordion background color when open only

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Hi guys, I'm having issues making my accordion background color change when open, currently it's the opposite of what I want, the colour of the heading changes when clicked, I want the contents of the accordion to change color when clicked. I think I would need to change the script which I don't really know how to do, can someone help?  Picture is an example of what I want it to look like

Here's the script: 

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script><script>
$(document).ready(function(){
$('.markdown-block .sqs-block-content h3').addClass('ui-closed').css('cursor','pointer');
$(".markdown-block .sqs-block-content h3").nextUntil("h3").slideToggle();
$(".markdown-block .sqs-block-content h3").click(function() {

$(this).nextUntil("h3").slideToggle();
$(this).toggleClass('ui-closed ui-open');
});
});
</script>

Here's the css: 

//markdown block for treatments

.markdown-block p {
  margin-left:1.5em;
  padding-right: 16px;
}
  .markdown-block h3 {
font-weight: 300 !important;

}
.markdown-block .ui-closed:before {
  content:"+ ";
}

.markdown-block .ui-open:before {
  content:"- ";
}
  
  .markdown-block {padding:20px;
  margin: 0 auto;
  width: 100% !important;
 }
  
.ui-open {
 background-color: #d2c8c2 !important;}

Hi,

Why you don't use Accordion Block to add accordion, instead of using Markdown + Script code

to change background, try adding this to Design > Custom CSS
 

h3.ui-open ~ * {
    background-color: #f1f2f3;
    margin-top: 0;
    margin-bottom: 0;
}

I have tables generated inside my markdown that don't seem to work in the squarespace accordions, I need it to be in the markdown