Reset padding for checkbox & radio inputs

Previously, the normalize stylesheet covered this, however that's
no longer applicable due to selector specificity.

client/scss/elements/_forms.scss

@@ -154,6 +154,7 @@ input[type=checkbox] {
     border-radius: 0;
     cursor: pointer;
     border: 0;
+    padding: 0;
 }
 
 input[type=radio] {