When you run your web application right from Visual Studio, a browser window comes with the desired page. One thing to notice here is, the size of the browser window. It remembers the last used browser window size and throws the output on a window of the same size.
So, if you are wondering if it's possible to run/debug your web application on a fixed sized web browser window, here is one of the under-utilized features of Visual Studio which helps in doing that.
Click on the dropdown just beside the browser name (Internet Explorer, mostly) on the Standard toolbar.
Click on "Browse With..."
A popup window will open up, find label "Size of browser window"
Choose the appropriate value from the dropdown and whenever you hit Run button a browser window with specified size will pop out.
Hopefully you enjoyed reading this. Thanks!