页面加载，主体先行

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网页打开总有一个下载的过程，哪些东西应该最先呈现？自然是主要部分了。

通常一个页面的结构，是导航条等公用信息放在头部，那么页面打开加载，也是先加载头部。

其实，头部这些公用信息不是用户最关心的，应该先加载主体部分。

我的做法是，将头部写在页面的底部，然后用绝对定位定在顶部，加载时，是主体先呈现，然后再到顶部。但加载完成后，跟原来看上去没什么两样的。