Again, it is hard to tell what is going on without the actual HTML from your child pages. However, judging from the picture, you are probably looking for a margin
value on a an element between your <asp:ContentPlaceHolder>
tags.
It looks like your second page is using a <table>
of some sort.
Make sure your table has:
style="margin-top: 0px;"
Or
<table class="noTopMargin"> ...
<style>
.noTopMargin { margin-top: 0px; }
</style>
As for the font-size
and font-weight
being messed up, it is possible that your second page has a <style>
declaration somewhere which is screwing it all up. Also make sure that your browser zoom is the same between both pages.