function subst() {
  var vars = {};
  var query_strings_from_url = document.location.search.substring(1).split('&');
  for (var query_string in query_strings_from_url) {
    if (query_strings_from_url.hasOwnProperty(query_string)) {
      var temp_var = query_strings_from_url[query_string].split('=', 2);
      vars[temp_var[0]] = decodeURI(temp_var[1]);
    }
  }

  var css_selector_classes = Object.keys(vars);
  for (var css_class in css_selector_classes) {
    if (css_selector_classes.hasOwnProperty(css_class)) {
      var element = document.getElementsByClassName(css_selector_classes[css_class]);
      for (var j = 0; j < element.length; ++j) {
        element[j].textContent = vars[css_selector_classes[css_class]];
      }
    }
  }
}