body background bootstrap 4 code example

Example 1: bootstrap color

primary - #007bff
secondary - #6c757d
success - #28a745
danger - #dc3545
warning - #ffc107
info - #17a2b8
light - #f8f9fa
dark - #343a40
muted - #6c757d
white - #ffffff

Example 2: bootstrap color a div

use something like :
<div class="container alert alert-success">
   <div class="row">
      <div class="col">I'm your content inside the grid!</div>
   </div>
</div>