Spiff up landing page a little

src/components/Calculator.scss

@@ -14,7 +14,3 @@
     }
   }
 }
-
-.index__class-picker {
-  margin: 2em 0;
-}

src/components/ClassPicker.scss

@@ -16,6 +16,10 @@
       opacity: 1;
     }
 
+    &:last-child {
+      margin-right: 0;
+    }
+
     &--active {
       opacity: 1;
     }