div style="position: absolute;"><math><mrow>${MathMLFragments[tag]}</mrow></math></div>`);
        let div = document.body.lastElementChild;
        let element = FragmentHelper.element(div.firstElementChild);

        test(function() {
            assert_true(MathMLFeatureDetection[`has_${tag}`](), `${tag} is supported`);
            var style = `width: 500px; height: 400px;`;
            element.setAttribute("style", style);
            let box = element.getBoundingClientRect();
            assert_approx_