script.js

var lastScrollTop = 0;
var firstSection = window.innerHeight;
var header = $("#navbar");

$(window).scroll(function (event) {
  var currentScroll = $(this).scrollTop();

  if (currentScroll < firstSection) {
    header.removeClass("dark");
  }

  if (currentScroll > lastScrollTop) {
    // Scrolling down
    header.slideUp();
  } else {
    // Scrolling up
    if (currentScroll > firstSection) {
      header.slideDown(); // Show header
      header.addClass("dark");
    } else {
      header.slideDown(); // Show header
    }
  }

  lastScrollTop = currentScroll;
});

$("#hamburger").click(function () {
  $(this).toggleClass("ham-open");
  $(".ham-menu").toggleClass("menu-open");

  $(window).scroll(function (event) {
    $("#hamburger").removeClass("ham-open");
    $(".ham-menu").removeClass("menu-open");
  });
});