text: export function slideDown(el, options = {}) {
      el.style.display = ''
      const height = el.offsetHeight
  
      el.style.maxHeight = '0'
      el.style.overflow = 'hidden'
      el.style.transition = `max-height ${ options.duration || '0.5s' } ease`
  
      el.addEventListener('transitionend', function end(){
          el.removeEventListener('transitionend', end)
  
          el.style.maxHeight = ''
          el.style.overflow = ''
          el.style.transition = ''
  
          if( "done" in options ){
              options.done()
          }
      });
  
      requestAnimationFrame(() => requestAnimationFrame(() => {
          el.style.maxHeight = height + 'px';
      }))
  }
  
  export function slideUp(el, options = {}) {
      el.style.maxHeight = el.offsetHeight + 'px'
      el.style.overflow = 'hidden'
      el.style.transition = `max-height ${ options.duration || '0.5s' } ease`
  
      el.addEventListener('transitionend', function end(){
          el.removeEventListener('transitionend', end)
  
          el.style.maxHeight = ''
          el.style.overflow = ''
          el.style.transition = ''
          el.style.display = 'none'
  
          if( "done" in options ){
              options.done()
          }
      });
  
      requestAnimationFrame(() => requestAnimationFrame(() => {
              el.style.maxHeight = '0'
      }))
  }
  