JSFiddle - React, Tailwind, and code Playground

by lollero

CSS

.under500 {
    background: red;
}

.over700 {
    background: green;
}

JavaScript

var win = $(window),
    body = $(document.body);

winsize();

win.on("resize", winsize);

function winsize() {

    if ( win.width() < 500 ) {
    
        body
          .removeClass()
          .addClass('under500');
            
    }
    else if ( win.width() > 800 ) {
    
        body
          .removeClass()
          .addClass('over700');
            
    }
    else {
            
       body.removeClass();
        
    }

}