The Bar chart shown here is an example of responsive charts so you can change the size of your browser window and see the effect on them. This is an result of by using option's method "getResponsiveFunction".
<?php

include_once "environment.php";
use phpRGraph\rgraph_chart;
use phpRGraph\rgraph_options;

// rgraph chart
$template = "default.php";
$id = "cvs";
$chart_type = "Bar";
$draw_option = "draw();";
$width = "500";
$height = "350";
$data = array( 40,50,80,30,50,60,70 );
$labels = array('Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday');

$chart = new rgraph_chart("cvs", $data, "Bar");
$options = new rgraph_options("default.ini");
$options->set_option("title", "A Simple Bar Chart");
$options->set_option("xaxisLabels", $labels);
$options->set_tooltip($data, "#label# <br> #val#");
$options->set_option("xaxisLabelsAngle", 20);
$options->set_option("variant","glass");
$draw_option .= $options->getResponsiveFunction(array(0.4,990,1200,$width,$height));

$chart->set_options($options);
$rgraph_json = $chart->toString();

$chart_script = "";
$event_script = "";

include_once ($templates . $template);
?>