Columns Stacked 1

By adding stack1 to the outer div, columns will stack to 1 column on widths less than 768px.

<div class="f4 stack1">
    <div class="one">
        Column 1
    </div>
    <div class="two">
        Column 2
    </div>
</div>

Here's the available columns and output:

2 columns

3 columns

4 columns

5 columns

6 columns

7 columns

8 columns