//下面控制顯示彈唔彈公告
show_box();
function show_box(){
document.getElementById('black-bg').style.display='block';
document.getElementById('cbox').style.display='block';
var item = document.getElementById('cbox').getBoundingClientRect();
var h = item.height;
var w = item.width;
document.getElementById('cbox').style.left = (window.innerWidth-w)/2+'px';
document.getElementById('cbox').style.top = (window.innerHeight-h)/2+'px';
}
function hide_box(){
document.getElementById('black-bg').style.display='none';
document.getElementById('cbox').style.display='none';
}
