masterpages and css - asp.net

Question

i set some css rules and html tags, that looks desirable in the design view. But when a child form of the masterpage loads the page, it looks different. Can a child css rules dominate the properties of a parent css rules.
style type="text/css">
#container{position:relative;}
img#border{position:absolute;
}
#placeH{position:absolute; left:344px;
top: 325px;
height: 168px;
width: 708px;
bottom:287px;
}
<title></title>
<asp:ContentPlaceHolder id="head" runat="server">
</asp:ContentPlaceHolder>
</head>
<div align="center" id="container">
<asp:Image ID="Header" runat="server" ImageUrl="~/header.png" Width="1196px"
Height="280px" />
</div>
<div id="border">
<asp:Image ID="Image1" runat="server" ImageUrl="~/border.png"/>// the border
that i try to set here appears fine in the masterpage design view..but on the childs
design view,,it appears at the bottom left of the page
</div>
<div id="placeH">
<form id="form1" runat="server">
<asp:ContentPlaceHolder id="ContentPlaceHolder2" runat="server">
</asp:ContentPlaceHolder>
</form>
</div>
</body>

Answer 1

the only thing that I can see from here is that. You have some CSS that may not behave as you expect.
img#border{position:absolute;}
This will apply to an <img/> tag with the id="border". In the above HTML, you have an img inside a div with an id="border. You CSS for this should look something like.
div#border > img { postition:absolute; } if you want it applied to the image only.
or
#border { position:absolute; } if you want it applied to the whole div.
It is actually quite hard to see in the above HTML with the snippets. If the above does not solve it, paste the whole thing for me.

Answer 2

I think you should change the style of placeH into this.
#placeH{
position:absolute;
left:344px;
top: 325px;
height: 168px;
width: 708px;
}
^^
And yes, css from master page is applied for the child page.