D3.js add heading to graph : I want to add heading to my graph.
Something like this : 
[What i want to achieve...][1]

I have tried append.svg , append.text....etc
but nothing seems to work. I,m just not able to write the correct CSS for
this i guess.

This code here works:

    header= d3.select("svg").append("text")
        .attr("x", 70)             
        .attr("y", 20)
        .style("font-size", "16px") 
        .style("text-decoration", "underline")  
        .text("My graph heading...");

but i have problems in this one as i am unable to
assign it width and height and background fill.
When i assign it width or height it just does,nt gets applied.
Also changing the display to block is not working...

Running the code above makes a figure like this : 
[My current graph picture...][2]

  [1]: http://i.stack.imgur.com/lkREE.png
  [2]: http://i.stack.imgur.com/CRsGH.png

