Add background to individual page in Tremont template

Hello I want to add a pale grey background color to one single page in a Tremont family template and need to add CSS. I have tried various ways both in the page CSS itself and in the Custom CSS space under the Design tab but nothing seems to work. I have added the body collection for the page following the code below  but that doesn't work either so any help would be most welcome. Thanks!

.collection-5db98c973799b8041e990326 { 
      background-color: #cccccc !important; 
} 

Hi @elm,

Try the below instead.

#collection-5db98c973799b8041e990326 .main-content{ 
      background-color: #cccccc !important; 
}