createTooltip = el => {
el
.attr("class", "tooltip")
.style("border-radius", "3px")
.style("pointer-events", "none")
.style("display", "none")
.style("position", "absolute")
.style("z-index", "1000")
.style("padding", "12px")
.style("font-weight", "regular")
.style("font-family", "Open Sans")
.style("font-size", "12px")
.style("background", "white")
.style("box-shadow", "0 0 10px rgba(0,0,0,.25)")
.style("color", "#333333")
.style("line-height", "1.6")
.style("pointer-events", "none");
}