text: // define Varabile global
  let oneServ = true;
  let oneAbout = true;
  var lastScrollTop = 0;
  const firstText = document.getElementById('firsText');
  const secText = document.getElementById('secondText');
  let arrFigure = document.getElementsByClassName('gallery')[0].children;
  let arrAbout = document.querySelector('#about article').children;
  // define Varabile global
  
  // hidden element
  arrAbout[0].style.right = '-500px';
  arrAbout[0].style.opacity = '0';
  arrAbout[1].style.opacity = '0';
  for(let i = 0; i < arrFigure.length; i++){
      arrFigure[i].style.left = '-40px';
      arrFigure[i].style.opacity = '0';
      arrFigure[i].style.transition = 'all 2s ease-in-out';
  }
  
  firstText.style.left = '-580px';
  secText.style.left = '-580px';
  // hidden element
  setTimeout(() => {
      // define transition 
  document.getElementById('navMenu').style.transition = 'all 2s ease-in-out';
  firstText.style.transition = 'left 3s ease-in-out';
  secText.style.transition = 'left 3s ease-in-out';
  arrAbout[0].style.transition = 'all 2s ease-in-out';
  arrAbout[1].style.transition = 'all 2s ease-in-out';
  for(let i = 0; i < arrFigure.length; i++){
      arrFigure[i].style.transition = 'all 2s ease-in-out';
  }
  
  // define transition
  }, 300);
  
  
  function menuMove(){
      let scrollPosition = window.pageYOffset;
      let navClass = document.getElementById('navMenu');
      if(scrollPosition > 100 && navClass.className == "menu" ){
          navClass.classList.add('toggleMenu');
      }else if(scrollPosition < 80 && navClass.className == "menu toggleMenu" ){
          navClass.classList.remove('toggleMenu');
      }
  }
  function galleryMove(){
      let services = document.getElementById('services').getBoundingClientRect().top;
      if(services < window.innerHeight/2 && oneServ){
          oneServ = false;
          let timer = 300;
          for(let i = 0; i < arrFigure.length; i++){
              setTimeout(()=>{
                  arrFigure[i].style.left = '0';
                  arrFigure[i].style.opacity = '1';
              },timer);
              timer += 200;
          }
      }
  }
  function aboutMove(){
      let about = document.getElementById('about').getBoundingClientRect().top;
      if(about < window.innerHeight/2 && oneAbout){
          oneAbout = false;
          setTimeout(()=>{
              arrAbout[0].style.right = '0';
              arrAbout[0].style.opacity = '1';
              },700);
          setTimeout(()=>{
              arrAbout[1].style.opacity = '1';
              },2500);
      }
  }
  function arrowvisibility(){
      var st = window.pageYOffset || document.documentElement.scrollTop;
      if (st > lastScrollTop){
          // downscroll code
          document.querySelector('.arrowUp').style.visibility = 'visible';
      } else {
          // upscroll code
          document.querySelector('.arrowUp').style.visibility = 'hidden';
      }
      lastScrollTop = st <= 0 ? 0 : st;
  }
  
  function slideText(){
      setTimeout(()=>{firstText.style.left = '0'}, 1000);
      setTimeout(()=>{secText.style.left = '0'}, 3000);
  }
  
  // define event listener
  window.addEventListener('scroll', menuMove);
  window.addEventListener('scroll', galleryMove);
  window.addEventListener('scroll', aboutMove);
  window.addEventListener('scroll', arrowvisibility);
  window.addEventListener('load', slideText);
  
  
  