前端ABC在CSS中，让元素隐藏（指屏幕范围内肉眼不可见）的方法很多，有的占据空间，有的不占据空间；有的可以响应点击，有的不能响应点击
{ display: none; }
{ visibility: hidden; }
{ position: absolute; top: -999em; }
{ position: relative; top: -999em; }
{ position: absolute; visibility: hidden; }
{ height: 0; overflow: hidden; }
{ opacity: 0; filter:Alpha(opacity=0); }
{ position: absolute; opacity: 0; filter:Alpha(opacity=0); }
{
zoom: 0.001;
-moz-transform: scale(0);
-webkit-transform: scale(0);
-o-transform: scale(0);
transform: scale(0);
}
{
position: absolute;
zoom: 0.001;
-moz-transform: scale(0);
-webkit-transform: scale(0);
-o-transform: scale(0);
transform: scale(0);
}