(experiment) add script for offset to pubhist page

pubhist.html

@@ -5,6 +5,41 @@
 permalink: /pubhist.html
 ---
 
+<script>
+
+// experiment to compensate for page header when jumping to anchors
+// code from https://www.geeksforgeeks.org/offsetting-an-anchor-to-adjust-for-fixed-header/?ref=gcse_ind
+// this is their option 2 for address this visual glitch
+
+  // Get the header element
+  let header = document.querySelector('header');
+
+  // Get the height of the header
+  let headerHeight = header.offsetHeight;
+  document.querySelectorAll('a[href^="#"]')
+  .forEach(function (anchor) {
+      anchor.addEventListener('click', 
+      function (event) {
+          event.preventDefault();
+
+          // Get the target element that 
+          // the anchor link points to
+          let target = document.querySelector(
+              this.getAttribute('href')
+          );
+
+          let targetPosition = target
+              .getBoundingClientRect().top - headerHeight;
+
+          window.scrollTo({
+              top: targetPosition + window.pageYOffset,
+              behavior: 'smooth'
+          });
+      });
+  });
+</script>
+
+
 <main id="main">
   <section>
     <div class="container" id="introduction">