fdo#75040 fix application of help's stylesheet

it was regression from 73e3aafa

Change-Id: I059f08b12bb7847472946f3b2a669015ec437be5

sw/source/filter/html/htmlcss1.cxx

@@ -642,7 +642,7 @@ static CSS1SelectorType GetTokenAndClass( const CSS1Selector *pSelector,
         }
     }
 
-    rToken = rToken.toAsciiUpperCase();
+    rToken = rToken.toAsciiLowerCase();
     return eType;
 }