How do I make an edge stuck to the screen?

I was trying to make a border glued to the sides of the screen how represents the picture below :

Picture of how i want

I have html code, but i don´t know if i´m doing in the best way. Can you guys help me?

DIV Rectangle HTMl

<div class="content">
    This is a rectangle!
 </div

DIV Rectangle CSS:

.content {

   width:100%;
   min-height: 150%;
   border:1px solid #FFFF;
   border-width: 100%;
   background-color: #FFFF;
   border-radius: 5px;
   padding-bottom: 50%;

}

It is like this:

Picture of how it is

I want to remove this spacing between border and screen, is it possible to do that?