背景色を変更する

bg-{prefix}

それぞれ背景色に応じた文字色が定義されます

bg-primary bg-success bg-info bg-warning bg-danger

<span class="bg-primary">bg-primary</span>
<span class="bg-success">bg-success</span>
<span class="bg-info">bg-info</span>
<span class="bg-warning">bg-warning</span>
<span class="bg-danger">bg-danger</span>

bg-primary

bg-success

bg-info

bg-warning

bg-danger

<p class="bg-primary">bg-primary</p>
<p class="bg-success">bg-success</p>
<p class="bg-info">bg-info</p>
<p class="bg-warning">bg-warning</p>
<p class="bg-danger">bg-danger</p>