Template:Popper/styles.css

      #tooltip {
        background: #333;
        color: white;
        font-weight: bold;
        padding: 4px 8px;
        font-size: 13px;
        border-radius: 4px;
        display: none;
      }

      #tooltip[data-show] {
        display: block;
      }

      #arrow,
      #arrow::before {
        position: absolute;
        width: 8px;
        height: 8px;
        background: inherit;
      }

      #arrow {
        visibility: hidden;
      }

      #arrow::before {
        visibility: visible;
        content: '';
        transform: rotate(45deg);
      }

      #tooltip[data-popper-placement^='top'] > #arrow {
        bottom: -4px;
      }

      #tooltip[data-popper-placement^='bottom'] > #arrow {
        top: -4px;
      }

      #tooltip[data-popper-placement^='left'] > #arrow {
        right: -4px;
      }

      #tooltip[data-popper-placement^='right'] > #arrow {
        left: -4px;
      }