arm-api/public/assets/css/morris.css

.morris-hover {
   position: absolute;
   z-index: 1000;
}

.morris-hover.morris-default-style {
   border-radius: 3px;
   padding: 6px;
   color: #333;
   background: rgba(255, 255, 255, 0.8);
   border: 1px solid #ddd;
   font-size: 12px;
   text-align: center;
}

.morris-hover.morris-default-style .morris-hover-row-label {
   font-weight: bold;
   margin: 0.25em 0;
}

.morris-hover.morris-default-style .morris-hover-point{
   white-space: nowrap;
   margin: 0.1em 0;
}