Trello power-up set modal width by percent

Question

Hello there I am currently making a power-up for trello with popup function.

I would like to know if it's possible to set the popup modal of trello to percent '75%'.

  var boardButtonCallback = function(t){
  return t.popup({
    title: 'Time calculater',
    items: [
      {
        text: 'Weekly statistics',
        callback: function(t){
          return t.modal({
            url: './template/statistics/weekly.html',
            height: '75%',
            width: '75%',
          })
          .then(function(){
            return t.closePopup();
          });
        }
      }
    ]
  });
};

this is my code to call the modal and display it to the user. as you can see I tried using percent but it doesn't work. is there a way to do this with percent?