Background
Convey meaning through background-color
and add decoration with gradients.
.visually-hidden
class.
Background color
Similar to the contextual text color classes, set the background of an element to any contextual class. Background utilities do not set color
, so in some cases you’ll want to use .text-*
color utilities.
.bg-*
that generated from our original $theme-colors
Sass map don’t yet respond to color modes, however, any .bg-*-subtle
utility will. This will be resolved in v6.
<div class="p-3 mb-2 bg-primary text-white">.bg-primary</div>
<div class="p-3 mb-2 bg-primary-subtle text-primary-emphasis">.bg-primary-subtle</div>
<div class="p-3 mb-2 bg-secondary text-white">.bg-secondary</div>
<div class="p-3 mb-2 bg-secondary-subtle text-secondary-emphasis">.bg-secondary-subtle</div>
<div class="p-3 mb-2 bg-success text-white">.bg-success</div>
<div class="p-3 mb-2 bg-success-subtle text-success-emphasis">.bg-success-subtle</div>
<div class="p-3 mb-2 bg-danger text-white">.bg-danger</div>
<div class="p-3 mb-2 bg-danger-subtle text-danger-emphasis">.bg-danger-subtle</div>
<div class="p-3 mb-2 bg-warning text-dark">.bg-warning</div>
<div class="p-3 mb-2 bg-warning-subtle text-warning-emphasis">.bg-warning-subtle</div>
<div class="p-3 mb-2 bg-info text-dark">.bg-info</div>
<div class="p-3 mb-2 bg-info-subtle text-info-emphasis">.bg-info-subtle</div>
<div class="p-3 mb-2 bg-light text-dark">.bg-light</div>
<div class="p-3 mb-2 bg-light-subtle text-light-emphasis">.bg-light-subtle</div>
<div class="p-3 mb-2 bg-dark text-white">.bg-dark</div>
<div class="p-3 mb-2 bg-dark-subtle text-dark-emphasis">.bg-dark-subtle</div>
<div class="p-3 mb-2 bg-body-secondary">.bg-body-secondary</div>
<div class="p-3 mb-2 bg-body-tertiary">.bg-body-tertiary</div>
<div class="p-3 mb-2 bg-body text-body">.bg-body</div>
<div class="p-3 mb-2 bg-black text-white">.bg-black</div>
<div class="p-3 mb-2 bg-white text-dark">.bg-white</div>
<div class="p-3 mb-2 bg-transparent text-body">.bg-transparent</div>
Background gradient
By adding a .bg-gradient
class, a linear gradient is added as background image to the backgrounds. This gradient starts with a semi-transparent white which fades out to the bottom.
Do you need a gradient in your custom CSS? Just add background-image: var(--bs-gradient);
.
Opacity
Added in v5.1.0As of v5.1.0, background-color
utilities are generated with Sass using CSS variables. This allows for real-time color changes without compilation and dynamic alpha transparency changes.
How it works
Consider our default .bg-success
utility.
.bg-success {
--bs-bg-opacity: 1;
background-color: rgba(var(--bs-success-rgb), var(--bs-bg-opacity)) !important;
}
We use an RGB version of our --bs-success
(with the value of 25, 135, 84
) CSS variable and attached a second CSS variable, --bs-bg-opacity
, for the alpha transparency (with a default value 1
thanks to a local CSS variable). That means anytime you use .bg-success
now, your computed color
value is rgba(25, 135, 84, 1)
. The local CSS variable inside each .bg-*
class avoids inheritance issues so nested instances of the utilities don’t automatically have a modified alpha transparency.
Example
To change that opacity, override --bs-bg-opacity
via custom styles or inline styles.
<div class="bg-success p-2 text-white">This is default success background</div>
<div class="bg-success p-2" style="--bs-bg-opacity: .5;">This is 50% opacity success background</div>
Or, choose from any of the .bg-opacity
utilities:
<div class="bg-success p-2 text-white">This is default success background</div>
<div class="bg-success p-2 text-white bg-opacity-75">This is 75% opacity success background</div>
<div class="bg-success p-2 text-dark bg-opacity-50">This is 50% opacity success background</div>
<div class="bg-success p-2 text-dark bg-opacity-25">This is 25% opacity success background</div>
<div class="bg-success p-2 text-dark bg-opacity-10">This is 10% opacity success background</div>
CSS
In addition to the following Sass functionality, consider reading about our included CSS custom properties (aka CSS variables) for colors and more.
Sass variables
Most background-color
utilities are generated by our theme colors, reassigned from our generic color palette variables.
$blue: #0d6efd;
$indigo: #6610f2;
$purple: #6f42c1;
$pink: #d63384;
$red: #dc3545;
$orange: #fd7e14;
$yellow: #ffc107;
$green: #198754;
$teal: #20c997;
$cyan: #0dcaf0;
$primary: $blue;
$secondary: $gray-600;
$success: $green;
$info: $cyan;
$warning: $yellow;
$danger: $red;
$light: $gray-100;
$dark: $gray-900;
$gradient: linear-gradient(180deg, rgba($white, .15), rgba($white, 0));
Grayscale colors are also available, but only a subset are used to generate any utilities.
$white: #fff;
$gray-100: #f8f9fa;
$gray-200: #e9ecef;
$gray-300: #dee2e6;
$gray-400: #ced4da;
$gray-500: #adb5bd;
$gray-600: #6c757d;
$gray-700: #495057;
$gray-800: #343a40;
$gray-900: #212529;
$black: #000;
Variables for setting background-color
in .bg-*-subtle
utilities in light and dark mode:
$primary-bg-subtle: tint-color($primary, 80%);
$secondary-bg-subtle: tint-color($secondary, 80%);
$success-bg-subtle: tint-color($success, 80%);
$info-bg-subtle: tint-color($info, 80%);
$warning-bg-subtle: tint-color($warning, 80%);
$danger-bg-subtle: tint-color($danger, 80%);
$light-bg-subtle: mix($gray-100, $white);
$dark-bg-subtle: $gray-400;
$primary-bg-subtle-dark: shade-color($primary, 80%);
$secondary-bg-subtle-dark: shade-color($secondary, 80%);
$success-bg-subtle-dark: shade-color($success, 80%);
$info-bg-subtle-dark: shade-color($info, 80%);
$warning-bg-subtle-dark: shade-color($warning, 80%);
$danger-bg-subtle-dark: shade-color($danger, 80%);
$light-bg-subtle-dark: $gray-800;
$dark-bg-subtle-dark: mix($gray-800, $black);
Sass maps
Theme colors are then put into a Sass map so we can loop over them to generate our utilities, component modifiers, and more.
$theme-colors: (
"primary": $primary,
"secondary": $secondary,
"success": $success,
"info": $info,
"warning": $warning,
"danger": $danger,
"light": $light,
"dark": $dark
);
Grayscale colors are also available as a Sass map. This map is not used to generate any utilities.
$grays: (
"100": $gray-100,
"200": $gray-200,
"300": $gray-300,
"400": $gray-400,
"500": $gray-500,
"600": $gray-600,
"700": $gray-700,
"800": $gray-800,
"900": $gray-900
);
RGB colors are generated from a separate Sass map:
$theme-colors-rgb: map-loop($theme-colors, to-rgb, "$value");
Background color opacities build on that with their own map that’s consumed by the utilities API:
$utilities-bg: map-merge(
$utilities-colors,
(
"black": to-rgb($black),
"white": to-rgb($white),
"body": to-rgb($body-bg)
)
);
$utilities-bg-colors: map-loop($utilities-bg, rgba-css-var, "$key", "bg");
$utilities-bg-subtle: (
"primary-subtle": var(--#{$prefix}primary-bg-subtle),
"secondary-subtle": var(--#{$prefix}secondary-bg-subtle),
"success-subtle": var(--#{$prefix}success-bg-subtle),
"info-subtle": var(--#{$prefix}info-bg-subtle),
"warning-subtle": var(--#{$prefix}warning-bg-subtle),
"danger-subtle": var(--#{$prefix}danger-bg-subtle),
"light-subtle": var(--#{$prefix}light-bg-subtle),
"dark-subtle": var(--#{$prefix}dark-bg-subtle)
);
Color mode background colors are also available as a Sass map:
$theme-colors-bg-subtle: (
"primary": $primary-bg-subtle,
"secondary": $secondary-bg-subtle,
"success": $success-bg-subtle,
"info": $info-bg-subtle,
"warning": $warning-bg-subtle,
"danger": $danger-bg-subtle,
"light": $light-bg-subtle,
"dark": $dark-bg-subtle,
);
$theme-colors-bg-subtle-dark: (
"primary": $primary-bg-subtle-dark,
"secondary": $secondary-bg-subtle-dark,
"success": $success-bg-subtle-dark,
"info": $info-bg-subtle-dark,
"warning": $warning-bg-subtle-dark,
"danger": $danger-bg-subtle-dark,
"light": $light-bg-subtle-dark,
"dark": $dark-bg-subtle-dark,
);
Sass mixins
No mixins are used to generate our background utilities, but we do have some additional mixins for other situations where you’d like to create your own gradients.
@mixin gradient-bg($color: null) {
background-color: $color;
@if $enable-gradients {
background-image: var(--#{$prefix}gradient);
}
}
// Horizontal gradient, from left to right
//
// Creates two color stops, start and end, by specifying a color and position for each color stop.
@mixin gradient-x($start-color: $gray-700, $end-color: $gray-800, $start-percent: 0%, $end-percent: 100%) {
background-image: linear-gradient(to right, $start-color $start-percent, $end-color $end-percent);
}
// Vertical gradient, from top to bottom
//
// Creates two color stops, start and end, by specifying a color and position for each color stop.
@mixin gradient-y($start-color: $gray-700, $end-color: $gray-800, $start-percent: null, $end-percent: null) {
background-image: linear-gradient(to bottom, $start-color $start-percent, $end-color $end-percent);
}
@mixin gradient-directional($start-color: $gray-700, $end-color: $gray-800, $deg: 45deg) {
background-image: linear-gradient($deg, $start-color, $end-color);
}
@mixin gradient-x-three-colors($start-color: $blue, $mid-color: $purple, $color-stop: 50%, $end-color: $red) {
background-image: linear-gradient(to right, $start-color, $mid-color $color-stop, $end-color);
}
@mixin gradient-y-three-colors($start-color: $blue, $mid-color: $purple, $color-stop: 50%, $end-color: $red) {
background-image: linear-gradient($start-color, $mid-color $color-stop, $end-color);
}
@mixin gradient-radial($inner-color: $gray-700, $outer-color: $gray-800) {
background-image: radial-gradient(circle, $inner-color, $outer-color);
}
@mixin gradient-striped($color: rgba($white, .15), $angle: 45deg) {
background-image: linear-gradient($angle, $color 25%, transparent 25%, transparent 50%, $color 50%, $color 75%, transparent 75%, transparent);
}
Sass utilities API
Background utilities are declared in our utilities API in scss/_utilities.scss
. Learn how to use the utilities API.
"background-color": (
property: background-color,
class: bg,
local-vars: (
"bg-opacity": 1
),
values: map-merge(
$utilities-bg-colors,
(
"transparent": transparent,
"body-secondary": rgba(var(--#{$prefix}secondary-bg-rgb), var(--#{$prefix}bg-opacity)),
"body-tertiary": rgba(var(--#{$prefix}tertiary-bg-rgb), var(--#{$prefix}bg-opacity)),
)
)
),
"bg-opacity": (
css-var: true,
class: bg-opacity,
values: (
10: .1,
25: .25,
50: .5,
75: .75,
100: 1
)
),
"subtle-background-color": (
property: background-color,
class: bg,
values: $utilities-bg-subtle
),