I am making a topnav and I don't want space between the body and the div element.

I want to look like that. But the thing is, I do not know how I can 'delete' or 'remove' the space between the body and the <div> element.
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title> Why Linux is just better than Windows - Ring Tips </title>
    <link rel="icon" href="linux.png">
</head>
<body>
     <style>
          body {
               background: #484d49;
               padding: 0;
               -webkit-font-smoothing: antialised;
          }
          .topnav {
               top: 0;
               position: sticky;
               background: #a5b0a8;
               border: 0.5px solid black;
               width: 100%;
               height: 100px;
               overflow: hidden;
               z-index: 2;
          }
     </style>
     <div class="topnav"></div>
</body>
</html>
That's what I have done, but how can I use CSS or JavaScript to delete the space between the elements.
If you could help, that'd be great.
Thanks,
Ring Games