 = 2 * emToPx;

          element = document.getElementById("small_vertical");
          assert_approx_equals(element.getBoundingClientRect().width, .5 * emToPx, epsilon, "small width");
          assert_approx_equals(element.getBoundingClientRect().height, tallest_base_size, epsilon, "height is the max(.5em, 1em, 2em)");

          element = document.getElementById("medium_vertical");
          assert_approx_equals(element.getBoundingClientRect().width, 1 * emToPx, epsilon, "normal width");
          asser