Wybrany element staje sie fixed po scrollowaniu do tego elementu #js #css

fixed_element_after_scrolling.js

  var fixmeTop = $('.element-fixed');
  if (fixmeTop.length) {
    var fixmeTopLength = fixmeTop.offset().top;       // get initial position of the element
  }
  $(window).scroll(function() {                  // assign scroll event listener
      var currentScroll = $(window).scrollTop(); // get current position
      if (currentScroll >= fixmeTopLength) {           // apply position: fixed if you
          $('.element-fixed').css({  // scroll to that element or below it
              'position': 'fixed',
              'top': '137px',
              'z-index':'999',
              'width': '100%',
              'left': '0',
          });
      } else {  // apply position: static
          $('.element-fixed').css({ // if you scroll above it
              'position': 'static'
          });
      }
  });