滚动页面时，如何使div保持在其他div的顶部？

Question

Pls help me. I've tried.

This is my code presently

HTML

    <div id="header"><!--beggining of header-->

    </div><!--end of header-->

CSS

    #header {
    width: auto;
    height: 100px;
    background-color: #F0F;
    border-bottom-style: solid;
    border-bottom-color: #000;
    position: fixed;
    }

SORRY. THIS IS MY FIRST TIME USING THIS STE. I CANT POST THE CODE. BUT SEE THE FULL HTML HERE

Answer 1

check this fiddle

html:

<div class="cover">
  top
   <div class="fixed-box">
     hello                            
   </div>
</div>

css:

.fixed-box {
  width:100px;/*just for preview*/
  height:100px;/*just for preview*/
  background:red;/*just for preview*/
  position:fixed;
  top:10px;
}
.cover {
  width:500px;/*just for preview*/
  height:10000px;/*just for preview*/
  background:blue;/*just for preview*/
}

Answer 2

#header {width: auto; height: 100px; background-color: #F0F; border-bottom-style: solid;
    border-bottom-color: #000; position: fixed; top:0px; z-index:100;}

please make sure after the header div make one container div for content and make that div position:relative; z-index:50; position:relative; z-index:50;