consul/ui/packages/consul-ui/app/components/topology-metrics/series/skin.scss

#metrics-container .sparkline-wrapper {
  svg path {
    stroke-width: 0;
  }

  .tooltip {
    padding: 0 0 10px;
    font-size: 0.875em;
    line-height: 1.5em;
    font-weight: normal;
    border: 1px solid $gray-300;
    background: #fff;
    border-radius: 2px;
    box-sizing: border-box;
    box-shadow: 0px 4px 8px rgba(0, 0, 0, 0.05), 0px 4px 4px rgba(0, 0, 0, 0.1);

    .sparkline-time {
      padding: 8px 10px;
      font-weight: bold;
      font-size: 14px;
      color: #000;
      border-bottom: 1px solid $gray-200;
      margin-bottom: 4px;
      text-align: center;
    }

    .sparkline-tt-legend,
    .sparkline-tt-sum {
      border: 0;
      padding: 3px 10px 0 10px;
    }

    .sparkline-tt-sum {
      border-top: 1px solid $gray-200;
      margin-top: 4px;
      padding: 8px 10px 0 10px;
    }

    .sparkline-tt-legend-color {
      width: 12px;
      height: 12px;
      border-radius: 2px;
      margin: 0 5px 0 0;
      padding: 0;
    }

    .sparkline-tt-legend-value,
    .sparkline-tt-sum-value {
      float: right;
    }
  }

  div.tooltip:before{
    content:'';
    display:block;
    position: absolute;
    width: 12px;
    height: 12px;
    left: 15px;
    bottom: -7px;
    border: 1px solid $gray-300;
    border-top: 0;
    border-left: 0;
    background: #fff;
    transform: rotate(45deg);
  }
}

// Key modal
.sparkline-key {
  h3::before {
      @extend %with-info-circle-fill-mask, %as-pseudo;
      margin: 2px 3px 0 0;
      font-size: 14px;
  }

  h3 {
    color: $gray-900;
    font-size: 16px;
  }

  .sparkline-key-content {
    dt {
      font-weight: 600;
    }
    dd {
      color: $gray-500;
    }
  }
}

.sparkline-key-link {
  color: $gray-500;
}
.sparkline-key-link:hover {
  color: $blue-500;
}
#metrics-container:hover .sparkline-key-link::before {
  @extend %with-info-circle-fill-mask, %as-pseudo;
  margin: 1px 3px 0 0;
  font-size: 12px;
}