Scroll fix for modal body

HTML

<div id="container">
    <div id="something-else"><h1>Header</h1></div>
    <div id="overflow">
        Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.     Modal body content goes here.       
    </div>
</div>

CSS

#container {
  border: 1px solid red;
  width: 200px;
  height: 250px; /* This can be any height and everything fills in */
  padding-top: 55px;            
}
#something-else {
  height: 55px;
  width: 200px;
  background-color: green;
  margin-top:-55px;    
}
#overflow {
  border: 1px solid blue;
  width:198px;
  overflow-y: auto; 
  height: 100%;   
}