created burger menu and added responsive styles for navbar, optimized element positions in header
diff --git a/dev/js/src/init.js b/dev/js/src/init.js
index 5b0e7d1..60f961a 100644
--- a/dev/js/src/init.js
+++ b/dev/js/src/init.js
@@ -131,15 +131,28 @@
     let prevScrollPos = window.scrollY;
 
     window.onscroll = function() {
+      const navbar = document.querySelector('.navbar');
       let currentScrollPos = window.scrollY;
       if (prevScrollPos > currentScrollPos) {
-          document.querySelector('.navbar').style.top = '0';
+          navbar.style.top = '0';
       } else {
-          document.querySelector('.navbar').style.top = '-3rem';
+        if (!navbar.classList.contains('show')) {
+          navbar.style.top = '-3rem';
+        }
       }
       prevScrollPos = currentScrollPos;
     }
 
+    // Responsive navbar: hide and show burger menu
+    document.querySelector('.burger-icon').addEventListener('click', function() {
+      const navbar = document.querySelector('.navbar');
+      if (navbar.className === 'navbar') {
+        navbar.className += ' show';
+      } else {
+        navbar.className = 'navbar';
+      }
+    })
+
     /**
      * Replace Virtual Corpus field
      */