Negative Margin in Firefox Using Bootstrap

Negative Margin in Firefox Using Bootstrap

I am using Twitter Bootstrap plugin, mainly just the grid system currently.
I am trying to put one row on top of another doing some stuff for
responsive design.
In Chrome this works perfectly:
<div class="container">
<div class="row">
<div class="content">
abcd
</div>
</div>
<div class="row" id="moveUpRow">
<div class="content">
efgh
</div>
</div>
</div>
CSS:
.row {
height: 200px;
}
#moveUpRow {
margin-top: -200px;
}
But in Firefox and IE they both ignore the negative margin. I have tried
top: -200px, but that just moves up the row and not all of the elements
below the row. Leaving big white space.
Any other solutions to this problem? Or any suggestions on how to "pull"
up any content below the row?