rderTopWidth;
const mediumWidth = getComputedStyle(box).borderRightWidth;
const thickWidth = getComputedStyle(box).borderBottomWidth;

test_computed_value("border-inline-start-width", "calc(10px + 0.5em)", "30px");
test_computed_value("border-inline-start-width", "calc(10px - 0.5em)", "0px");
test_computed_value("border-inline-start-width", "thin", thinWidth);
test_computed_value("border-inline-start-width", "medium", mediumWidth);

test_computed_value("border-inline-end-width", "calc(10px + 0.5em)", "30px"