背景
.bg-primary
                  .bg-secondary
                  .bg-success
                  .bg-danger
                  .bg-warning
                  .bg-info
                  .bg-light
                  .bg-dark
                  .bg-indigo
                  .bg-purple
                  .bg-pink
                  .bg-yellow
                  .bg-cyan
                  .bg-brown
                  .bg-teal
                  .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-indigo text-white">.bg-indigo</div>
      <div class="p-3 mb-2 bg-purple text-white">.bg-purple</div>
      <div class="p-3 mb-2 bg-pink text-white">.bg-pink</div>
      <div class="p-3 mb-2 bg-yellow text-white">.bg-yellow</div>
      <div class="p-3 mb-2 bg-cyan text-white">.bg-cyan</div>
      <div class="p-3 mb-2 bg-brown text-white">.bg-brown</div>
      <div class="p-3 mb-2 bg-teal text-white">.bg-teal</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>
                背景渐变
你的自定义CSS需要渐变吗?只需添加 background-image: var(--bs-gradient); 。
.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
                .bg-indigo.bg-gradient
                .bg-purple.bg-gradient
                .bg-pink.bg-gradient
                .bg-yellow.bg-gradient
                .bg-cyan.bg-gradient
                .bg-brown.bg-gradient
                .bg-teal.bg-gradient
                不透明度
这是默认的 success 背景
                  这是 50% 不透明度的 success 背景
                <div class="bg-success p-2 text-white">这是默认的 success 背景</div>
      <div class="bg-success p-2" style="--bs-bg-opacity: .5;">这是 50% 不透明度的 success 背景</div>
                或者,从任何一个选项中选择 .text-opacity 相关类:
这是默认的 success 背景
                  这是 75% 不透明度的 success 背景
                  这是 50% 不透明度的 success 背景
                  这是 25% 不透明度的 success 背景
                  这是 10% 不透明度的 success 背景
                <div class="bg-success p-2 text-white">这是默认的 success 背景</div>
      <div class="bg-success p-2 text-white bg-opacity-75">这是 75% 不透明度的 success 背景</div>
      <div class="bg-success p-2 text-dark bg-opacity-50">这是 50% 不透明度的 success 背景</div>
      <div class="bg-success p-2 text-dark bg-opacity-25">这是 25% 不透明度的 success 背景</div>
      <div class="bg-success p-2 text-dark bg-opacity-10">这是 10% 不透明度的 success 背景</div>