.screenmiddle{
    position: absolute;
    top: 40px;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}

.getdown{
    margin-top: 55px;
    margin-bottom: 80px;
}

.node circle {
    fill: #999;
}

.node text {
    font: 12px sans-serif;
}

.node--internal circle {
    fill: #555;
}

.node--internal text {
    text-shadow: 0 1px 0 #fff, 0 -1px 0 #fff, 1px 0 0 #fff, -1px 0 0 #fff;
}

.link {
    fill: none;
    stroke: #555;
    stroke-opacity: 0.4;
    stroke-width: 1.5px;
}