#target { box-sizing: border-box; display: block; transition-property: height, margin, padding; transition-duration: 500ms; height: 0; overflow: hidden; padding-top: 0; padding-bottom: 0; margin-top: 0; margin-bottom: 0; }target.style.overflow = 'hidden';
target.style.height = 0;
target.style.paddingTop = 0;
target.style.paddingBottom = 0;
target.style.marginTop = 0;
target.style.marginBottom = 0;
target.offsetHeight;
target.style.boxSizing = 'border-box';
target.style.transitionProperty = "height, margin, padding";
target.style.transitionDuration = duration + 'ms';
target.style.height = height + 'px';
target.style.removeProperty('padding-top');
target.style.removeProperty('padding-bottom');
target.style.removeProperty('margin-top');
target.style.removeProperty('margin-bottom');
window.setTimeout( () => {
target.style.removeProperty('height');
target.style.removeProperty('overflow');
target.style.removeProperty('transition-duration');
target.style.removeProperty('transition-property');
}, duration);
}