finished age

main/_data/about.json

@@ -1,6 +1,6 @@
 [{
         "q": "How old are you?",
-        "a": "I'm XXX years old. This automatically updates now, too, so I won't ever forget to update it again!"
+        "a": "I'm <span id=\"age\"></span> years old. This automatically updates now, too, so I won't ever forget to update it again!"
     },
     {
         "q": "Where are you from?",

main/_includes/about.html

@@ -12,4 +12,10 @@
         </p>
         {% endfor %}
     </div>
+    <script>
+        let birthdayMillis = Date.UTC(1999, 5 - 1, 21);
+        let todayMillis = Date.now();
+        let ageSinceStart = new Date(todayMillis - birthdayMillis);
+        $("#age").html(ageSinceStart.getUTCFullYear() - 1970);
+    </script>
 </div>