border-dark

bootstrap5.css

bootstrap5.css
.border-dark {
  border-color: #343a40 !important;
}

html bootstrap5 Sample

ボーダー色を設定する:border-*


border-primary border-secondary border-success border-danger border-warning border-info border-light border-dark border-white
  <span class="border border-primary">border-primary</span>
  <span class="border border-secondary">border-secondary</span>
  <span class="border border-success">border-success</span>
  <span class="border border-danger">border-danger</span>
  <span class="border border-warning">border-warning</span>
  <span class="border border-info">border-info</span>
  <span class="border border-light">border-light</span>
  <span class="border border-dark">border-dark</span>
  <span class="border border-white">border-white</span>