BS BG Color
<!-- Bootstrap colors, gradiants and opacity -->
bg-primary
bg-secondary
bg-success
bg-danger
bg-warning
bg-info
bg-light
bg-dark
bg-body
bg-white
bg-transparent
<!-- to add gradiants -->
bg-primary.bg-gradient
<!-- to add opacity -->
style="--bs-bg-opacity: .5;" or, bg-opacity-50
Fahim Foysal