Improve random selection of array elements to fix header animations (#119)

diff --git a/landing-pages/src/js/headerAnimation.js b/landing-pages/src/js/headerAnimation.js
index 3f4f56c..3829801 100644
--- a/landing-pages/src/js/headerAnimation.js
+++ b/landing-pages/src/js/headerAnimation.js
@@ -29,7 +29,7 @@
 
 const randomBetween = (from, to) => from + Math.random() * (to - from);
 const randomInt = (from, to) => Math.round(randomBetween(from, to));
-const randomItem = (arr) => arr[randomInt(0, arr.length)];
+const randomItem = (arr) => arr[randomInt(0, arr.length - 1)];
 
 class Polygon {
   constructor(pos, vectors) {