css - How to make borders collapse (on a div)?

Question

Suppose I have markup like: http://jsfiddle.net/R8eCr/1/

<div class="container">
    <div class="column">
        <div class="cell"></div>
        <div class="cell"></div>
        <div class="cell"></div>
    </div>
    <div class="column">
        <div class="cell"></div>
        <div class="cell"></div>
        <div class="cell"></div>
    </div>
    <div class="column">
        <div class="cell"></div>
        <div class="cell"></div>
        <div class="cell"></div>
    </div>
    ...
</div>

Then CSS

.container {
    display: table;
    border-collapse: collapse;
}
.column {
    float: left;
    overflow: hidden;
    width: 120px;
}
.cell {
    display: table-cell;
    border: 1px solid red;
    width: 120px;
    height: 20px;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

I have the outer div with display: table; border-collapse: collapse; and cells with display: table-cell why do they still not collapse? What am I missing here?

By the way there maybe variable number of cells in a column so I can't only have borders on one side.

Answer 1

Use simple negative margin rather than using display table.

Updated in fiddle JS Fiddle

.container { 
    border-style: solid;
    border-color: red;
    border-width: 1px 0 0 1px;
    display: inline-block;
}
.column { 
    float: left; overflow: hidden; 
}
.cell { 
    border: 1px solid red; width: 120px; height: 20px; 
    margin:-1px 0 0 -1px;
}
.clearfix {
    clear:both;
}