This is a test of hiding a div on a web page when the window size is less than a specified value. In this case the window will be hidden if it is less than 600 pixels. You can test it by reducing the size of your browser window and then refreshing the display of the web page in the browser.
This is the div to be hidden when the browser window is less than the specified width.
This is the end of the web page. See Hiding an element on a webpage with JavaScript