//ie6 position fixed bug fix
var vs=window.navigator.appVersion;
if (vs.indexOf( 'MSIE 6' )!=-1) {
document.getElementById( 'pop' ).style.top=(document.documentElement.scrollTop+(window.screen.availHeight)/2)+ 'px' ;
window.οnscrοll= function () {
document.getElementById( 'pop' ).style.top=(document.documentElement.scrollTop+(window.screen.availHeight)/2)+ 'px' ;