Is there a straightforward way to put my Shiny app in a div/container that will make the app's size standardized across different monitors?

Hi everyone,

I have a simple Shiny app built using shinydashboard. I place elements inside each box, and try to do what I can to make the sizing work well across different computer monitors. (i.e., adding scrolling to a datatable).

However, some plots just do not size well or I cannot force them to be constrained within one of the boxes.

I tried a method I found online, allowing a Shiny app to be embedded in a website using iframe. This works when hosting my app on a website, because I can make all boxes/plots/tables within the app standard no matter who views them.....however, with my current app I am keeping it on the shinyapps.io site.

How can I approach this?