     assert_approx_equals(remove.height, 0, epsilon);
        assert_approx_equals(remove.top, baseline, epsilon);
    }, "dynamic attributes (remove)");

    test(function() {
        let attach = getBox("dynamic-attach");
        assert_approx_equals(attach.width, 50, epsilon);
        assert_approx_equals(attach.height, 60 + 70, epsilon);
        assert_approx_equals(baseline - attach.top, 60, epsilon);
    }, "dynamic attributes (attach)");

    test(function() {
        let modify = getBox("dynamic-mod