function reveal () {
  const reveals = document.querySelectorAll('.reveal')

  for (let i = 0; i < reveals.length; i++) {
    const windowHeight = window.innerHeight
    const elementTop = reveals[i].getBoundingClientRect().top
    const elementVisible = 150

    if (elementTop < windowHeight - elementVisible) {
      reveals[i].classList.add('active')
      reveals[i].classList.remove('reveal')
    } else {
      reveals[i].classList.remove('active')
    }
  }
}

window.addEventListener('scroll', reveal)