bootstrap4.css
progress {
  vertical-align: baseline;
}
bootstrap4.css
@-webkit-keyframes progress-bar-stripes {
  from {
    background-position: 1rem 0;
  }
  to {
    background-position: 0 0;
  }
}
bootstrap4.css
@keyframes progress-bar-stripes {
  from {
    background-position: 1rem 0;
  }
  to {
    background-position: 0 0;
  }
}
bootstrap4.css
.progress {
  display: -ms-flexbox;
  display: flex;
  height: 1rem;
  overflow: hidden;
  font-size: 0.75rem;
  background-color: #e9ecef;
  border-radius: 0.25rem;
}
bootstrap4.css
.progress-bar {
  display: -ms-flexbox;
  display: flex;
  -ms-flex-direction: column;
  flex-direction: column;
  -ms-flex-pack: center;
  justify-content: center;
  color: #fff;
  text-align: center;
  white-space: nowrap;
  background-color: #007bff;
  transition: width 0.6s ease;
}
bootstrap4.css
@media (prefers-reduced-motion: reduce) {
  .progress-bar {
    transition: none;
  }
}
bootstrap4.css
.progress-bar-striped {
  background-image: linear-gradient(45deg, rgba(255, 255, 255, 0.15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, 0.15) 50%, rgba(255, 255, 255, 0.15) 75%, transparent 75%, transparent);
  background-size: 1rem 1rem;
}
bootstrap4.css
.progress-bar-animated {
  -webkit-animation: progress-bar-stripes 1s linear infinite;
  animation: progress-bar-stripes 1s linear infinite;
}
bootstrap4.css
@media (prefers-reduced-motion: reduce) {
  .progress-bar-animated {
    -webkit-animation: none;
    animation: none;
  }
}
■プログレスバー:progress::基本的な使用例

 <div class="progress mb-3">
    <div class="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar" style="width: 20%" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar w-50" role="progressbar" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar" style="width: 80%" role="progressbar" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress">
    <div class="progress-bar w-100" role="progressbar" aria-valuenow="100" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーの背景 bg-success

  <div class="progress mb-3">
    <div class="progress-bar bg-success" role="progressbar" style="width: 25%" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーの背景 bg-info

  <div class="progress mb-3">
    <div class="progress-bar bg-info" role="progressbar" style="width: 50%" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーの背景 bg-warning

  <div class="progress mb-3">
    <div class="progress-bar bg-warning" role="progressbar" style="width: 75%" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーの背景 bg-danger

  <div class="progress mb-3">
    <div class="progress-bar bg-danger" role="progressbar" style="width: 100%" aria-valuenow="100" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーのストライプをアニメーションさせる

  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped progress-bar-animated" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100" style="width: 25%"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped progress-bar-animated bg-success" role="progressbar" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100" style="width: 50%"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped progress-bar-animated bg-info" role="progressbar" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100" style="width: 75%"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped progress-bar-animated bg-danger" role="progressbar" aria-valuenow="100" aria-valuemin="0" aria-valuemax="100" style="width: 100%"></div>
  </div>
  
■プログレスバー:progress::プログレスバーの太さ(高さ) 1pxの太さのプログレスバー

  <div class="progress mb-5" style="height: 1px;">
    <div class="progress-bar w-25" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーの太さ(高さ)20pxの太さのプログレスバー

  <div class="progress" style="height: 20px;">
    <div class="progress-bar w-25" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
■プログレスバー:progress::プログレスバーにテキストラベルを追加する

25%
  <div class="progress">
    <div class="progress-bar w-25" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">25%</div>
  </div>
■プログレスバー:progress::複数のプログレスバーを積み重ねる

  <div class="progress">
    <div class="progress-bar" role="progressbar" style="width: 15%" aria-valuenow="15" aria-valuemin="0" aria-valuemax="100"></div>
    <div class="progress-bar bg-success" role="progressbar" style="width: 30%" aria-valuenow="30" aria-valuemin="0" aria-valuemax="100"></div>
    <div class="progress-bar bg-info" role="progressbar" style="width: 20%" aria-valuenow="20" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  
■プログレスバー:progress::プログレスバーをストライプにする

  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped" role="progressbar" style="width: 10%" aria-valuenow="10" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped bg-success" role="progressbar" style="width: 25%" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped bg-info" role="progressbar" style="width: 50%" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped bg-warning" role="progressbar" style="width: 75%" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100"></div>
  </div>
  <div class="progress mb-3">
    <div class="progress-bar progress-bar-striped bg-danger" role="progressbar" style="width: 100%" aria-valuenow="100" aria-valuemin="0" aria-valuemax="100"></div>
  </div>