I have included Bootstrap 3.4.1 in the below HTML page through CDN.
HTML Page
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>HTML Page</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css"
integrity="sha384-HSMxcRTRxnN+Bdg0JdbxYKrThecOKuH5zCYotlSAcp1+c8xmyTe9GYg1l9a69psu" crossorigin="anonymous">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap-theme.min.css"
integrity="sha384-6pzBo3FDv/PJ8r2KRkGHifhEocL+1X2rVCTTkUfGk7/0pbek5mMa1upzvWbrUbOZ" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.min.js"
integrity="sha384-aJ21OjlMXNL5UyIl/XNwTMqvzeRMZH2w8c5cRVpzpU8Y5bApTppSuUkhZXN0VxHd"
crossorigin="anonymous"></script>
</head>
<body>
<div class="container-fluid">
<div class="row">
<div class="col-sm-4 bg-primary">grid content</div>
<div class="col-sm-4 bg-primary">grid content</div>
<div class="col-sm-4 bg-primary">grid content</div>
</div>
</div>
</body>
</html>
My question is simple: why does a row have a right and left margin of -15 pixels?
We can simply remove the right and left padding of the fluid container, this will create the same effect.