Adjust size of Shiny progress bar and center it

I'm working with a Shiny app where I need to calculate processes and while the calc progress is executing, I'm using a progressBar to show the process.

The problem is that the progress bar is too small, and I don't like the way is shown.

So, I was thinking that maybe there's a way to implement a progress bar using a Shiny modal (there's a function called modalDialog).

My idea is that when the user runs the calc, a modal will be opened showing a progressBar.

This is the progress code:

withProgress(message = 'Runing GSVA', value = 0, {
    incProgress(1, detail = "This may take a while...")
    functionToGenerate()
  })

Any idea?