Remove flex shorthand

sass/layout/header.sass

@@ -86,7 +86,7 @@ a.header-item
 .header-left
   align-items: stretch
   display: flex
-  flex: 1
+  flex-grow: 1
   overflow: hidden
   overflow-x: auto
   white-space: nowrap
@@ -113,7 +113,7 @@ a.header-item
   & > .header-item
     align-items: stretch
     display: flex
-    flex: 1
+    flex-grow: 1
     justify-content: center
     padding: 0
     & > a

sass/layout/hero.sass

@@ -38,7 +38,7 @@
   flex-shrink: 0
 
 .hero-body
-  flex: 1
+  flex-grow: 1
   padding: 40px 20px
   // Responsiveness
   +desktop
@@ -143,4 +143,4 @@
       align-items: center
       display: flex
       & > .container
-        flex: 1
+        flex-grow: 1