.html

 <div id="chart_wrap">
      <div id="chart">
        <img src="images/spinner.gif" alt="loading...">
      </div>
      <div id="selector">
        <a id="pie_graph_button" class="button">Show Pie Chart</a>
        <a id="bar_graph_button" class="button active">Show Bar Graph</a>
        <a id="line_graph_button" class="button">Show Line Graph</a>
      </div>
    </div>

onload.js

  $(function() {
    build_bar_graph("d");
    $('#bar_graph_button').click(build_bar_graph("d"));
    $('#pie_graph_button').click(build_pie_chart("d"));
    $('#line_graph_button').click(build_line_graph("d"));
  });

sdf.css

#pie_graph_button{
  top: 506px;
  left: 253px;
  height: 77px;
  width: 128px;
  background: url(images/pie_chart.png) 0 100%;
}

#pie_graph_button:hover {
  background: url(images/pie_chart.png) 0 0;
}

#line_graph_button {
  top: 480px;
  left: 580px;
  height: 124px;
  width: 128px;
  background: url(images/line_chart.png) 0 100%;
}

#line_graph_button:hover {
  background: url(images/line_chart.png) 0 0;
}

#bar_graph_button {
  top: 480px;
  left: 420px;
  height: 128px;
  width: 119px;
  background: url(images/bar_graph.png) 0 100%;
}

#bar_graph_button:hover {
  background: url(images/bar_graph.png) 0 0;
}