title: HighChart width greater than col-sm in Bootstrap
body: <p>I'm working with Bootstrap and HighChart. I'm making a web page in witch I need show a plot in a tablets or desktops PC. This is my html code:</p>
  
  <pre><code>&lt;div id="container-fluid"&gt;
   &lt;div class="row"&gt;
  
     &lt;div class="col-sm-6"&gt;
       &lt;div class="box"&gt;
         &lt;div id="plot1" style="width:100%; margin: 0 auto"&gt;&lt;/div&gt;
       &lt;/div&gt;&lt;!-- box --&gt;
     &lt;/div&gt;&lt;!-- col-sm-6 --&gt;
  
   &lt;/div&gt;&lt;!-- row --&gt;
  &lt;/div&gt;&lt;!-- container-fluid --&gt;
  </code></pre>
  
  <p>And this is my plot script:</p>
  
  <pre><code>$(function () {
  $('#plot1').highcharts({
      title: {
          text: 'Monthly Average Temperature',
          x: -20 //center
      },
      subtitle: {
          text: 'Source: WorldClimate.com',
          x: -20
      },
      xAxis: {
          categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
           'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
      },
      yAxis: {
          title: {
              text: 'Temperature (°C)'
          },
          plotLines: [{
              value: 0,
              width: 1,
              color: '#808080'
          }]
      },
      tooltip: {
          valueSuffix: '°C'
      },
      legend: {
          layout: 'vertical',
          align: 'right',
          verticalAlign: 'middle',
          borderWidth: 0
      },
      series: [{
          name: 'Tokyo',
          data: [7.0, 6.9, 9.5, 14.5, 18.2, 21.5, 25.2, 26.5, 23.3, 18.3, 13.9, 9.6]
      }, {
          name: 'New York',
          data: [-0.2, 0.8, 5.7, 11.3, 17.0, 22.0, 24.8, 24.1, 20.1, 14.1, 8.6, 2.5]
      }, {
          name: 'Berlin',
          data: [-0.9, 0.6, 3.5, 8.4, 13.5, 17.0, 18.6, 17.9, 14.3, 9.0, 3.9, 1.0]
      }, {
          name: 'London',
          data: [3.9, 4.2, 5.7, 8.5, 11.9, 15.2, 17.0, 16.6, 14.2, 10.3, 6.6, 4.8]
      }]
  });
  
  $('#plot1').highcharts().reflow();
  })
  </code></pre>
  
  <p>The problem to I have is, the plot has a width greater than the col-sm-6 (much more, almost like a col-sm-12). Why?
  Thanks!</p>