I am writng a R shiny web application using R studio. I am looking for a way to put the progress bar in the center of the webpage and adjust the size the of the bar. The function I used is “withProgress”, but I have the trouble to find the parameters for the location and size. Any suggestions?

withProgress(
      message = 'Running ......',
      detail = 'This may take a while.',
      value = 0,
      {
        ......
      }
    )