function FenrirRotateBanner() {
    var width = '120';
    var height = '120';
    var image_pref = 'http://resources.fenrir.co.jp/banner/grani/grani_';
    var image_suf = '_s.gif'
    var link = 'http://www.fenrir.co.jp/grani/';
    var colors = ['yellow', 'skyblue','rose','pink','orange','lightgray','green','darkgray','darkbrown','beige'];

    var num = Math.floor( Math.random() * colors.length );
    document.write(
        '<a href="'+link+'" target="_blank" title="Grani">'+
        '<img border="0" alt="Grani" class="fenrir_rotate_banner" src="'+image_pref+colors[num]+image_suf+'" width="'+width+'" height="'+height+'"/>'+
        '</a>'
    );
}
FenrirRotateBanner();