updated spacing utility class name
<body>
- <div class="m-b-1">
+ <div class="mb-1">
<nav class="navbar navbar-expand-md navbar-light bg-light">
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
