Андрей

html, body {
    width: 100%;
    height: 100%;
}
html {
    background: url(../img/background2.jpg) no-repeat center center fixed;
    background-size: auto auto;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}