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배경색

// Background

background-color를 통해 의미를 전달하고 그라디언트로 꾸밈을 추가 합니다.

배경색

상황별 텍스트 색상 클래스와 비슷하게 요소의 배경을 상황별 클래스로 설정합니다. background 유틸리티는 ** color 는 세팅하지 않습니다 **. 따라서 경우에 따라 .text- * 색상 유틸리티를 사용하는 것이 좋습니다.

.bg-primary

.bg-secondary

.bg-success

.bg-danger

.bg-warning

.bg-info

.bg-light

.bg-dark

.bg-body

.bg-white

.bg-transparent

<div class="p-3 mb-2 bg-primary text-white">.bg-primary</div>
<div class="p-3 mb-2 bg-secondary text-white">.bg-secondary</div>
<div class="p-3 mb-2 bg-success text-white">.bg-success</div>
<div class="p-3 mb-2 bg-danger text-white">.bg-danger</div>
<div class="p-3 mb-2 bg-warning text-dark">.bg-warning</div>
<div class="p-3 mb-2 bg-info text-dark">.bg-info</div>
<div class="p-3 mb-2 bg-light text-dark">.bg-light</div>
<div class="p-3 mb-2 bg-dark text-white">.bg-dark</div>
<div class="p-3 mb-2 bg-body text-dark">.bg-body</div>
<div class="p-3 mb-2 bg-white text-dark">.bg-white</div>
<div class="p-3 mb-2 bg-transparent text-dark">.bg-transparent</div>

배경 그라데이션

.bg-gradient 클래스를 추가하면 선형 그라데이션이 배경 이미지로 추가됩니다. 이 그라데이션은 아래쪽으로 희미 해지는 반투명 흰색으로 시작됩니다.

사용자 정의 CSS에 그라데이션이 필요하신가요? background-image : var (-bs-gradient);만 추가하면 됩니다.

.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

불투명도

v5.1.0에서 추가됨

As 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.

작동 방식

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.

예시

To change that opacity, override --bs-bg-opacity via custom styles or inline styles.

This is default success background

This is 50% opacity success background

<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:

This is default success background

This is 75% opacity success background

This is 50% opacity success background

This is 25% opacity success background

This is 10% opacity success background

<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>

Sass

다음 Sass 기능 외에도 색상 등이 포함 된 CSS 사용자 정의 속성 (일명 CSS 변수)에 대해 읽어보십시오.

변수

대부분의 background-color 유틸리티는 테마 색상에 의해 생성되며 일반 색상 팔레트 변수에서 재 지정됩니다.

$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;

맵

그런 다음 테마 색상은 Sass 맵에 배치되어 유틸리티, 컴포넌트 수정자 등을 생성하기 위해 반복할 수 있습니다.

$theme-colors: (
  "primary":    $primary,
  "secondary":  $secondary,
  "success":    $success,
  "info":       $info,
  "warning":    $warning,
  "danger":     $danger,
  "light":      $light,
  "dark":       $dark
);

회색조 색상은 Sass 맵으로도 사용할 수 있습니다. 이 맵은 유틸리티를 생성하는 데에 사용되지 않습니다.

$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
);

ㄴ RGB 색상은 별도의 Sass 맵에서 생성됩니다:

$theme-colors-rgb: map-loop($theme-colors, to-rgb, "$value");

그리고 배경색 불투명도는 유틸리티 API에서 사용하는 자체 맵을 기반으로 합니다:

$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");

믹스인

** 배경 유틸리티를 생성하는 데 믹스인이 사용되지는 않지만 **, 자신만의 그라데이션을 만들고 싶은 다른 상황을 위한 몇가지 추가 믹스인이 있습니다.

@mixin gradient-bg($color: null) {
  background-color: $color;

  @if $enable-gradients {
    background-image: var(--#{$variable-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);
}

유틸리티 API

백그라운드 유틸리티는 scss / _utilities.scss의 유틸리티 API에 선언되어 있습니다. 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
        )
      )
    ),
    "bg-opacity": (
      css-var: true,
      class: bg-opacity,
      values: (
        10: .1,
        25: .25,
        50: .5,
        75: .75,
        100: 1
      )
    ),