demo.css

body {
    width: 100%;
    margin: 0 auto;
    color: #333;
    font-weight: 300;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serf;
}

h1 {
    font-size: 3em;
    font-weight: 300;
}

h2 {
    font-size: 1.5em;
    font-weight: 300;
}

section {
    margin-bottom: 3em;
}

section p {
    text-align: justify;
}

svg {
    border: 1px solid #ccc;
    overflow: hidden;
    margin: 0 auto;
}

pre {
    border: 1px solid #ccc;
}

text {
    font-weight: 300;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serf;
    font-size: 14px;
}

.node rect {
    stroke: #333;
    fill: #fff;
    stroke-width: 1.5px;
    z-index: 3;
}

.edgePath path.path {
    stroke: #333;
    fill: none;
    stroke-width: 1.5px;
    z-index: 2;
}

.glower {
    z-index: 1;
}

.arrowhead {
    stroke: transparent;
    fill: none;
    stroke-width: 0px;
}