.chartOptions_button {
  background: $fillColor;
  margin-left: 5px; 
  color: $primaryBrandColor;
  border-radius: 2px;
  &:hover {
    cursor: pointer;
  }
  &.button_selected {
    color: $contentInverseColor;
    background: $primaryBrandColor;
    &:hover {
      color: $contentInverseColor;
      background: $primaryBrandColor;
    }
    [data-balloon] {
      &:before, &:after {
        opacity:0;
      }
    }
    &[data-balloon] {
      &:before, &:after {
        opacity:0;
      }
    }
  }

  span {
    border-bottom: 0px;
    cursor: pointer;
    display: inline-block;
    &[data-balloon]:before {
      padding: 0.5em;
      font-size: 0.8em;
      border: none;
      box-shadow: none;
      border-radius: 0px;
    }
  }
  .img {
    display: inline;

    div {
      width: 25px;
      height: 25px;
      margin: 5px;
      background-repeat: no-repeat;
      background-position: center;
    }
    img {
      width: 20px;
      height: 20px;
      margin: 5px;
    }
  }
}

.chartOptions_button {
  background: $fillColor;
  margin-left: 5px; 
  color: $primaryBrandColor;
  border-radius: 2px;
  &:hover {
    cursor: pointer;
  }
  &.button_selected {
    color: $contentInverseColor;
    background: $primaryBrandColor;
    &:hover {
      color: $contentInverseColor;
      background: $primaryBrandColor;
    }
    [data-balloon] {
      &:before, &:after {
        opacity:0;
      }
    }
    &[data-balloon] {
      &:before, &:after {
        opacity:0;
      }
    }
  }

  span {
    border-bottom: 0px;
    cursor: pointer;
    display: inline-block;
    &[data-balloon]:before {
      padding: 0.5em;
      font-size: 13px;
      border: none;
      box-shadow: none;
      border-radius: 0px;
    }
  }
  .img {
    display: inline;

    div {
      width: 25px;
      height: 25px;
      margin: 5px;
      background-repeat: no-repeat;
      background-position: center;
    }
    img {
      width: 20px;
      height: 20px;
      margin: 5px;
    }
  }
}

Use pixels for data-balloon font-size
Use pixels for data-balloon font-size

Since ie renders `em` differently than other browsers, it caused the data-balloon text to me much smaller that it was supposed to be, also was harder too read.