mikeyuriev

const content = document.querySelector('.content'),
         contentHeight = document.querySelector('.content').clientHeight,
         contentBtn = document.querySelector('.content-btn');
     
if(contentHeight > 50) {
  content.classList.add('content-hide')
  contentBtn.style.display = "block"
} else {
  contentBtn.style.display = "none"
}

contentBtn.addEventListener('click', function() {
  content.classList.toggle('content-show')
})

content.addEventListener('transitionend', function() {
  contentBtn.textContent = contentBtn.textContent === 'Подробнее' ? 'Скрыть' : 'Подробнее'
})

console.log(content)

.header::after {
  content: "";
  display: block;
  width: 174px;
}