Pre-define CSS background image center center position and cover background size

I am struggling to shorten down my CSS code for background image position (center center) and background size (cover).

Whenever I use the following code, it works fine, obviously:

HTML:

<div class="banner-divider" id="banner-divider-welcome"></div>
<div class="banner-divider" id="banner-divider-second"></div>

CSS:

.banner-divider{
width: 100%;
height:600px;
}
#banner-divider-welcome{
background: url(/images/welcome.jpg) no-repeat center center; 
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
#banner-divider-second{
background: url(/images/second.jpg) no-repeat center center; 
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}

I would like to shorten/delete multiple CSS repetitions of the center center and cover properties (as I have multiple banner ID's but with repeating background settings), however the following code does not center center and cover the images correctly:

HTML:

<div class="banner-divider" id="banner-divider-welcome"></div>
<div class="banner-divider" id="banner-divider-second"></div>

CSS:

.banner-divider{
width: 100%;
height:600px;
background: #fff;
background-image: none;
background-repeat: no-repeat
background-position: center center; 
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
#banner-divider-welcome{
background: url(/images/welcome.jpg); 
}
#banner-divider-second{
background: url(/images/second.jpg); 
}

What am I doing wrong?