[css-lists-3] Tweak general restrictions on ::marker to be more precise/correct. w3c#4568

Author: fantasai

css-lists-3/Overview.bs

@@ -224,10 +224,12 @@ Properties Applying to ''::marker''</h4>
     however at the moment outside marker box layout is not fully defined,
     so only these properties are allowed.
 
-  Other properties must not have an effect on the [=marker box=]
-  when set in the [=author origin=] of the [=cascade=].
+  Other properties should not have an effect on the [=marker box=]
+  when declared directly on ''::marker''
+  in the [=author origin|author=] or [=user origin=] of the [=cascade=].
   UAs may either treat such properties as not applying,
-  or enforce their value by setting a [=user-agent origin=] ''!important'' rule.
+  or enforce their value or inheritance from the [=originating element=]
+  by setting a [=user-agent origin=] ''!important'' rule.
   However, inheritable properties that apply to text
   can be set on the ''::marker'' pseudo-element:
   these will inherit to and take effect on its text contents.