Background Color in Bootstrap
.bg-primary
.bg-secondary
.bg-success
.bg-danger
.bg-warning
.bg-info
.bg-light
.bg-dark
.bg-body
.bg-white
.bg-transparent
Background Gradiant Color in Bootstrap
.bg-primary .bg-gradient
.bg-secondary .bg-gradient
.bg-success .bg-gradient
.bg-danger .bg-gradient
.bg-warning .bg-gradient
.bg-info .bg-gradient
.bg-light .bg-gradient
.bg-dark .bg-gradient
Background Opacity in Bootstrap
.bg-success Default Color
.bg-success Opacity-75
.bg-success Opacity-50
.bg-success Opacity-25
.bg-success Opacity-10