扩展时如何更改d3图表的宽度

Question

我试图在扩展时改变d3树形图的宽度？ 示例jsfiddle。 谢谢！

    var margin = {
    top: 20,
    right: 120,
    bottom: 20,
    left: 120
},
width = 960 - margin.right - margin.left,
height = 800 - margin.top - margin.bottom;