bg-color helper 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: change bootstrap background color
<style type="text/css">
body { background: navy !important; } /* Adding !important forces the browser to overwrite the default style applied by Bootstrap */
</style>