Live config sizing

Hey there! I am designing my live_config.html. I am using HTML and CSS for front-end styling. To test changes, I have just been opening the live_config.html with live server. I was happy with the changes and styling. I tried testing it on local and the styling was all off. I assume there is a set height and width a live_config page is?

If this is the case, does anyone know a line I can implement for responsive design to adapt my styling to the live_config dimensions?

And if there are specific dimension, what are they?

Live config broadly assumes similar dimensions to a panel

318px ish across
500px tall

(Off the top of my head)