/* background setup */
.background {
    background-repeat:no-repeat;
    /* custom background-position */
    background-position:50% 50%;
    /* ie8- graceful degradation */
    background-position:50% 50%\9 !important;
}

/* fullscreen setup */
html, body {
    /* give this to all tags from html to .fullscreen */
    height:100%;
}
.fullscreen,
.content-a {
    width:100%;
    min-height:100%;
}
.not-fullscreen,
.not-fullscreen .content-a,
.fullscreen.not-overflow,
.fullscreen.not-overflow .content-a {
    height:100%;
    overflow:hidden;
}

.not-fullscreen {
    height:50%;
}