CodePen

HTML

            
              .box
            
          
!

↑ Insert the most common viewport meta tag

CSS

            
              
            
          
!
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JS

            
              $.fn.BlueBox = function() {
  this.css({
    backgroundColor: 'blue',
    position: 'absolute',
    height: '60%',
    width: '60%',
    left: '20%',
    top: '20%'
  });
};

$( '.box' ).BlueBox();
            
          
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