色
Convey meaning through color with a handful of color utility classes. Includes support for styling links with hover states, too.
テキストの色
.text-primary
.text-secondary
.text-success
.text-danger
.text-warning
.text-info
.text-light
.text-dark
.text-muted
.text-white
<p class="text-primary">.text-primary</p>
<p class="text-secondary">.text-secondary</p>
<p class="text-success">.text-success</p>
<p class="text-danger">.text-danger</p>
<p class="text-warning">.text-warning</p>
<p class="text-info">.text-info</p>
<p class="text-light bg-dark">.text-light</p>
<p class="text-dark">.text-dark</p>
<p class="text-muted">.text-muted</p>
<p class="text-white bg-dark">.text-white</p>Contextual text classes also work well on anchors with the provided hover and focus states. Note that the .text-white and .text-muted class has no link styling.
<p><a href="#" class="text-primary">Primary link</a></p>
<p><a href="#" class="text-secondary">Secondary link</a></p>
<p><a href="#" class="text-success">Success link</a></p>
<p><a href="#" class="text-danger">Danger link</a></p>
<p><a href="#" class="text-warning">Warning link</a></p>
<p><a href="#" class="text-info">Info link</a></p>
<p><a href="#" class="text-light bg-dark">Light link</a></p>
<p><a href="#" class="text-dark">Dark link</a></p>
<p><a href="#" class="text-muted">Muted link</a></p>
<p><a href="#" class="text-white bg-dark">White link</a></p>背景色
Similar to the contextual text color classes, easily set the background of an element to any contextual class. Anchor components will darken on hover, just like the text classes. Background utilities do not set color, so in some cases you’ll want to use .text-* utilities.
<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-white">.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-white text-dark">.bg-white</div>背景のグラデーション
When $enable-gradients is set to true, you’ll be able to use .bg-gradient- utility classes. By default, $enable-gradients is disabled and the example below is intentionally broken. This is done for easier customization from the moment you start using Bootstrap. Learn about our Sass options to enable these classes and more.
<div class="p-3 mb-2 bg-gradient-primary text-white">.bg-gradient-primary</div>
<div class="p-3 mb-2 bg-gradient-secondary text-white">.bg-gradient-secondary</div>
<div class="p-3 mb-2 bg-gradient-success text-white">.bg-gradient-success</div>
<div class="p-3 mb-2 bg-gradient-danger text-white">.bg-gradient-danger</div>
<div class="p-3 mb-2 bg-gradient-warning text-dark">.bg-gradient-warning</div>
<div class="p-3 mb-2 bg-gradient-info text-white">.bg-gradient-info</div>
<div class="p-3 mb-2 bg-gradient-light text-dark">.bg-gradient-light</div>
<div class="p-3 mb-2 bg-gradient-dark text-white">.bg-gradient-dark</div>Dealing with specificity
Sometimes contextual classes cannot be applied due to the specificity of another selector. In some cases, a sufficient workaround is to wrap your element’s content in a <div> with the class.
支援技術に意図を伝える
色を用いて意図を伝えようとしても、視覚的な表示に終わるだけで、スクリーンリーダーなど支援技術のユーザには伝わりません。色で示された情報が、内容自体（可視テキストなど）から明らかであるか、.sr-only クラスの指定された隠しテキストなどの代替手段を通じて含まれていることを保証してください。