Genesis 2.0 Column Classes including 5 columns. The Genesis 2.0 stylesheet includes CSS for column classes of 2, 3, 4 and 6 columns. But it leaves out 5 columns. Here's the 2.0 column classes with the 5 column styles added back in.

genesis-20-columns.css

/* Column Classes
        Link: http://twitter.github.io/bootstrap/assets/css/bootstrap-responsive.css
--------------------------------------------- */

.five-sixths,
.four-sixths,
.four-fifths,
.one-fifth,
.one-fourth,
.one-half,
.one-sixth,
.one-third,
.three-fourths,
.three-fifths,
.three-sixths,
.two-fourths,
.two-fifths,
.two-sixths,
.two-thirds {
	float: left;
	margin-bottom: 20px;
	margin-left: 2.564102564102564%;
}

.one-half,
.three-sixths,
.two-fourths {
	width: 48.717948717948715%;
}

.one-third,
.two-sixths {
	width: 31.623931623931625%;
}

.four-sixths,
.two-thirds {
	width: 65.81196581196582%;
}

.one-fourth {
	width: 23.076923076923077%;
}

.three-fourths {
	width: 74.35897435897436%;
}

.one-fifth {
	width: 17.9487179487179488%;
}

.two-fifths {
	width: 38.4615384615384616%;
}

.three-fifths {
	width: 58.9743589743589744%;
}

.four-fifths {
	width: 79.4871794871794872%;
}

.one-sixth {
	width: 14.52991452991453%;
}

.five-sixths {
	width: 82.90598290598291%;
}

.first {
	clear: both;
	margin-left: 0;
}