Every time I change my samples my x axis appear shifted, I want to have it always as long as the chart . If someone could tell me what is happening it will be very helpful This is my code:

         
            <div id="y_axis"></div>
            <div id="chart"></div>
        
           <div id="x_axis"></div>
            
        </div>
..........
            var x_axis = new Rickshaw.Graph.Axis.X({
                graph: graph,
                orientation: 'bottom',
                tickSize: 6,
                //ticksTreatment: 'plain',                
                tickFormat: format,
                element: document.getElementById('x_axis'),
                pixelsPerTick: 75
                
                
            });
            
      ```