HTML side by side divs not filling full width

Question

I have the following quick html test which is a simplified version of something I am trying to do. What I am not sure about is why the "details" area (with red border doesn't line up on the right hand side with everything else. What am I doing wrong?

CSS:

.landscapepage {
    position:relative;
    width: 280mm;
    height: 190mm;
    page-break-after: always;
}

div.header {
    position:relative;
    min-height: 30mm;
    width: 100%;
    border-style:solid;
    border-width: medium;
    border-color:Gray;
    text-align:center;
}

div.footer {
    position:absolute;
    min-height:30mm;
    border-style:solid;
    border-width:medium;
    border-color:Gray;
    text-align:center;
    width: 100%;
    bottom: 0pt;
}

div.summary {
    position:relative;
    width: 80mm;
    min-height: 20mm;
    display:table-cell;
    border-style:solid;
    border-width:medium;
    border-color:Navy;
}

div.details {
    position:relative;
    display:table-cell;
    border-style:solid;
    border-width:medium;
    border-color:Red;
    min-height:20mm;
    width:100%;
}

HTML:

<div class="landscapepage">
    <div class="header">
        Header
    </div>
    <div class="summary">
        Summary
    </div>
    <div class="details">
        Details
    </div>
    <div class="footer">
        Footer
    </div>
</div>

Please see this jsFiddle .

Answer 1

It's all about border width.

When you set no borders, but background color you get something like this http://jsfiddle.net/cRZbw/1/ where "Details" is correctly aligned with "Header".

div.header {
    position:relative;
    min-height: 30mm;
    width: 100%;
    background:gray;
    text-align:center;    
    border:1px solid red;
}

div.footer {
    position:absolute;
    min-height:30mm;
    background:gray;
    text-align:center;
    width: 100%;
    bottom: 0pt;
}

div.summary {
    position:relative;
    width: 80mm;
    min-height: 20mm;
    display:table-cell;
    background:navy;
}

div.details {
    position:relative;
    display:table-cell;
    background:red;
    min-height:20mm;
    width:100%;
}

Answer 2

Might be you want to do this: http://jsfiddle.net/cRZbw/2/ Change div.footer's position to relative.

Here is the code:

div.footer {
    position:relative;
    min-height:30mm;
    border-style:solid;
    border-width:medium;
    border-color:Gray;
    text-align:center;
    width: 100%;
    bottom: 0pt;
}