Fix animations to pass Lighthouse (#5494)

Author: jnsiemer

_sass/minimal-mistakes/_animations.scss

@@ -4,7 +4,7 @@
 
 @-webkit-keyframes intro {
   0% {
-    opacity: 0;
+    opacity: 0.01;
   }
   100% {
     opacity: 1;
@@ -13,7 +13,7 @@
 
 @keyframes intro {
   0% {
-    opacity: 0;
+    opacity: 0.01;
   }
   100% {
     opacity: 1;