link color 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>