<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Превью</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-QWTKZyjpPEjISv5WaRU9OFeRpok6YctnYmDr5pNlyT2bRjXh0JMhjY6hW+ALEwIH" crossorigin="anonymous">
</head>
<body>
<div class="container">
<div class="row">
<div class="col-sm-12 col-nd-6 col-lg-4">
Блок номер 1
</div>
</div>
</div>
<div class="container">
<div class="row">
<div class="col-sm-12 col-nd-6 col-lg-4">
Блок номер 2
</div>
</div>
</div>
<div class="container">
<div class="row">
<div class="col-sm-12 col-nd-6 col-lg-4">
Блок номер 3
</div>
</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-YvpcrYf0tY3lHB60NNkmXc5s9fDVZLESaAA55NDzOxhy9GkcIdslK1eN7N6jIeHz" crossorigin="anonymous"></script>
</body>
</html>