is this a css problem

A user sent me a screenshot showing my leaderboard banner showing over the content of my webpage. For examples it normally is:
<leaderboard 720x90 ad>
<content>

but its doing this:
<content><leaderboard 720x90 ad>

So the banner is showing over the content and thus you are not able to see the content blocked by the banner.

When the page draws should it should reserve space for the banner and push the content down to show the banner.
I am using divs and float in the css but it shouldn't matter
What I think is happening is the webpage draws the ad last so the rest of the page loads and then the Ad gets drawn at the top and so just shows over the content already there instead of pushing the content down so the ad fits nicely.

It was like
<main div>

<adsense div>
<close adsense div>


<main content div>
<close main content div>

<close main div>



So all I could think of was to separate the sections



<adsense div>
<close adsense div>

<main div>

<main content div>
<close main content div>

<close main div>


And I tell adsense part to take as much room as needed

.Adwrapper {
width:890px;
height:auto; --making this auto seems to work better
text-align:left;
}

.Adwrapper {
width:890px;
height:90px; -- this makes the content get hidden by banner , which is what i dont want
text-align:left;
}





So is the ultimate fix to tell the main content to start at 100 pixels down from the top but that would look silly if the Adsense ad doesn't show which does happen.
I just want to reserver space for the banner ad. So why some users have this and not me I don't know why. It could be a browser issue.

 

Link the site.

css shouldn't be doing that though

 

If you want the ad to push down the content you have to build the ad within the div structure of your website. If it is floating above in a separate div, try moving the content down from where the content starts(might take a while) so the ad never covers content.