Fix selected tab highlight on next/prev button click

static/canvas.js

@@ -118,7 +118,7 @@ for (let i = 0; i < navElems.length; ++i) {
   }
 }
 
-let navButtons = document.querySelectorAll('.prevButton, .nextButton');
+let navButtons = document.querySelectorAll('.navButtons > a[href^="#"]');
 for (let i = 0; i < navButtons.length; ++i) {
   navButtons[i].onclick = function(e) {
     document.querySelector('nav > a[href="' + e.target.attributes.href.value + '"]').click();
@@ -153,7 +153,7 @@ window.addEventListener('load', function() {
   }
 
   // Add event listeners to inputs
-  let bgColorElems = document.querySelectorAll('.colorpicker input[type="radio"], #step3 input[type="radio"], #step4 input[type="radio"]');
+  let inputs = document.querySelectorAll('.colorpicker input[type="radio"], #step3 input[type="radio"], #step4 input[type="radio"]');
   for (let i = 0; i < bgColorElems.length; ++i) {
     bgColorElems[i].onchange = draw;
   }