Fit website background image to screen size

you can do this with this plugin http://dev.andreaseberhard.de/jquery/superbgimage/

or

   background-image:url(../IMAGES/background.jpg);

   background-repeat:no-repeat;

   background-size:cover;

with no need the prefixes of browsers. it's all ready suporterd in both of browers

Try this ,

 background: url(../IMAGES/background.jpg) no-repeat center center fixed; 
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;

For more information , follow this Perfect Full Page Background Image !!

You can try with

.appBackground {
    position: relative;
    background-image: url(".../img/background.jpg");
    background-repeat:no-repeat;
    background-size:100% 100vh;
}

works for me :)

Try this, I hope it will help:

position: fixed;
top: 0;
width: 100%;
height: 100%;
background-size: cover;
background-image: url('background.jpg');

Try this:

background: url(../IMAGES/background.jpg) no-repeat;
background-size: auto auto;