Simple CSS for Half-Width Columns

I was able to place two half-width columns on a page using the Column Shortcodes plugin, but having a plugin seems like overkill since all I want to do is use columns one time on one page.

How might I achieve the same thing pictured here using simple CSS and a div?

I tried doing this:

<div class="column">

	My content

</div>

with this CSS:

.column {
	padding: 15px;
}

but no dice. What am I neglecting here?

[Please don’t bump]