Multiple elements with same width equal to widest element

<span id="buttonsColumn">
	<button type="submit" name="powerSearchSubmitButton" id="powerSearchSubmitButton">
		<span><em><%=ViewData.Model.T9nProvider.TranslateById("CommonWeb.Search")%></em></span>
	</button>
	<a class="linkButton" href="something">
		<span><em><%=ViewData.Model.T9nProvider.TranslateById("CommonWeb.Advanced")%></em></span>
	</a>
</span>

#buttonsColumn {
    display: block;
    float: left;
    background-color: #F88;
}
#buttonsColumn button,
#buttonsColumn a {
    display: block;
}
#buttonsColumn button {
    width: 100%;
    background-color: #8F8;
}
#buttonsColumn a {
    width: 100%;
    background-color: #88F;
}

<table>
<tr>
    <td style="width:50%">
    <button type="submit" style="width:100%" name="powerSearchSubmitButton" id="powerSearchSubmitButton">
    	<span><em><%=ViewData.Model.T9nProvider.TranslateById("CommonWeb.Search")%></em></span>
    </button>
    </td>
    <td style="width:50%">
    <a class="linkButton" href="something">
    	<span><em><%=ViewData.Model.T9nProvider.TranslateById("CommonWeb.Advanced")%></em></span>
    </a>
    </td>
</tr>
</table>