Supervised user "learn more" page: Fix css flex usage.

chrome/browser/resources/options/supervised_user_learn_more.css

Index: chrome/browser/resources/options/supervised_user_learn_more.css
diff --git a/chrome/browser/resources/options/supervised_user_learn_more.css b/chrome/browser/resources/options/supervised_user_learn_more.css
index 9ff81cf5c4d9f8be39c1a549aa77214d239818ae..dfd55339d4a6c6e8723b5530b419d35f120e7c4d 100644
--- a/chrome/browser/resources/options/supervised_user_learn_more.css
+++ b/chrome/browser/resources/options/supervised_user_learn_more.css
@@ -3,6 +3,8 @@
  * found in the LICENSE file. */
 
 #supervised-user-learn-more {
+  display: flex;
+  flex-direction: column;
   width: 722px;
 }
 
@@ -31,7 +33,6 @@
       url(../../../../ui/resources/default_100_percent/supervised_illustration_start.png) 1x,
       url(../../../../ui/resources/default_200_percent/supervised_illustration_start.png) 2x);
   background-position: center;
-  flex: 1;
   height: 344px;
 }