            .d3-tip {
                line-height: 1;
                font-weight: bold;
                padding: 12px;
                background: rgba(0, 0, 0, 0.8);
                color: #fff;
                border-radius: 2px;
            }

            /* Creates a small triangle extender for the tooltip */
            .d3-tip:after {
                box-sizing: border-box;
                display: inline;
                font-size: 10px;
                width: 100%;
                line-height: 1;
                color: rgba(0, 0, 0, 0.8);
                content: "\25BC";
                position: absolute;
                text-align: center;
            }

            /* Style northward tooltips differently */
            .d3-tip.n:after {
                margin: -1px 0 0 0;
                top: 100%;
                left: 0;
            }
