プルダウンメニュー

  .form-control {
    display: block;
    width: 100%;
    padding: 0.375rem 0.75rem;
    font-size: 1rem;
    line-height: 1.5;
    color: #495057;
    background-color: #fff;
    background-clip: padding-box;
    border: 1px solid #ced4da;
    border-radius: 0.25rem;
    transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
  }

  select.form-control:not([size]):not([multiple]) {
    height: calc(2.25rem + 2px);
  }
  
  select.form-control:focus::-ms-value {
    color: #495057;
    background-color: #fff;
  }
    
    .custom-select {
      display: inline-block;
      width: 100%;
      height: calc(2.25rem + 2px);
      padding: 0.375rem 1.75rem 0.375rem 0.75rem;
      line-height: 1.5;
      color: #495057;
      vertical-align: middle;
      background: #fff url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 4 5'%3E%3Cpath fill='%23343a40' d='M2 0L0 2h4zm0 5L0 3h4z'/%3E%3C/svg%3E") no-repeat right 0.75rem center;
      background-size: 8px 10px;
      border: 1px solid #ced4da;
      border-radius: 0.25rem;
      -webkit-appearance: none;
      -moz-appearance: none;
      appearance: none;
    }
    .custom-select:focus {
      border-color: #80bdff;
      outline: 0;
      box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.075), 0 0 5px rgba(128, 189, 255, 0.5);
    }