A dark and graduated blue Bar chart

A dark and graduated Bar chart. The colors are black at the bottom of the bars graduating to blue towards the top. The background grid is customised too with the horizontal gridlines having been disabled. Nor is there any labels.

This goes in the documents header:
<script src="RGraph.svg.common.core.js"></script>
<script src="RGraph.svg.bar.js"></script>
Put this where you want the chart to show up:
<div style="width: 600px; height: 300px" id="chart-container"></div>
This is the code that generates the chart:
    data = [6,4,5,5,7,4,8];

    var bar = new RGraph.SVG.Bar({
        id: 'chart-container',
        data: data,
        options: {
            xaxis: false,
            yaxis: false,
            yaxisLabels: false,
            backgroundGridColor: '#999',
            backgroundGridHlines: false,
            backgroundGridBorder: false,
            colors: ['Gradient(#6969FF:#6969FF:#000)']