<?php
$bg = array('/common/images/base/wallpaper-007.png', '/common/images/base/wallpaper.png', '/common/images/base/wallpaper-001.png', '/common/images/base/wallpaper-002.png', '/common/images/base/wallpaper-003.png', '/common/images/base/wallpaper-004.png', '/common/images/base/wallpaper-005.png', '/common/images/base/wallpaper-006.png', '/common/images/base/wallpaper-008.png', '/common/images/base/wallpaper-009.png', '/common/images/base/wallpaper-010.png', '/common/images/base/wallpaper-011.png', '/common/images/base/wallpaper-012.png', '/common/images/base/wallpaper-013.png', '/common/images/base/wallpaper-014.png', '/common/images/base/wallpaper-015.png', '/common/images/base/wallpaper-017.png' ); // array of filenames
$i = array_rand($bg); // generate random number size of the array
$selectedBg = $bg[$i]; // set variable equal to which random filename was chosen
header('Content-Type: text/css');
?>
body, html {
    background: #000;
    padding: 0px;
    margin: 0px;
    width:100%;
    height: 100%;
    background-image: url(<?php echo "$selectedBg"; ?>);
    position: relative;
    background-size: cover;
    background-repeat: no-repeat;
    background-position: 0 0;
    background-attachment: fixed;
    -webkit-font-smoothing: antialiased;
}