Setting a ‘s display as table-cell

How about using a label? That way you get the functionality of the button, but the visibility of the label. Tested in Firefox and Chrome. Updated example for form submission.

• No JavaScript is involved with the clickability of the cell region
• Works without a fixed height on the container
• Works when a different cell has a larger height than the one with the button
• Works with multiple button cells

HTML:

<form onsubmit="alert(); return false;">
    <div class="container">
        <div class="item">1</div>
        <div class="item">2</div>
        <div class="item">3</div>
    </div>
    <div class="container">
        <div class="item">4</div>
        <div class="item">5<br><br><br>Extended cell</div>
        <label class="item">Button 1<button type="submit"></button></label>
        <label class="item">Button 2<button type="submit"></button></label>
    </div>
</form>

CSS:

.container {
    margin: 10px;
    border: 5px solid blue;
    display: table;
    table-layout: fixed;
    width: 300px;
}
.item {
    border: 3px solid red;
    display: table-cell;
}
.item button {
    background-color: transparent;
    position: absolute;
    left: -1000px;
    height: 1px;
    width: 1px;
    overflow: hidden;
}

JSFiddle here.