Colorful theme has two option about customizing colors.It is created for simple flat notifications.

$('#start').on('click',function(){
    $.amaran({
        'theme'     :'colorful',
        'content'   :{
           bgcolor:'#27ae60',
           color:'#fff',
           message:'Lorem ipsum dolor sit amet, consectetur adipisicing elit. Cupiditate, ducimus?'
        },
        'position'  :'bottom right',
        'outEffect' :'slideBottom'
    });
});