[cssom-1] Fix some nits

Author: upsuper

cssom-1/Overview.bs

@@ -2241,8 +2241,8 @@ a list of declarations <var>declarations</var>, the user agent must ensure the f
 Issue: Should we add something like "Any observable side effect must not be made outside
 <var>declarations</var>"? The current constraints sound like a hole for undefined behavior.
 
-Note: The steps of <a>set a CSS declaration</a> are not defined in this level of CSSOM. The user agent may
-use different algorithm as far as the constraints above hold.
+Note: The steps of <a>set a CSS declaration</a> are not defined in this level of CSSOM. User agents may
+use different algorithms as long as the constraints above hold.
 
 <div class="example">
  The simplest way to conform with the constraints would be to always remove any existing declaration