body { 
  background-color: maroon; 
} 

.mainbackground { 
  width: 290px; 
  height: 300px; 
  background-color: grey; 
  position: relative; 
  left: 12em; 
  top: 15em;
  
  border: 40px solid transparent; 
  border-image: url("/BackgroundThing/image-removebg-preview-13.png") 170 round; 
  border-image-outset: 10px; 
  
  border-width: 10px 0px; 
  
}