Fix un-themed buttons in logger

Related feedback:
- uBlockOrigin/uBlock-issues#1963 (comment)

Author: gorhill

src/logger-ui.html

@@ -142,7 +142,7 @@
             <div class="pane static" data-pane="static">
                 <div></div>
                 <div><textarea class="staticFilter" spellcheck="false"></textarea>
-                   <button id="createStaticFilter" class="important" type="button" data-i18n="pickerCreate">_<span class="hover"></span></button>
+                   <button id="createStaticFilter" class="preferred" type="button" data-i18n="pickerCreate">_<span class="hover"></span></button>
                </div>
             </div>
         </div>
@@ -160,7 +160,7 @@
 
     <div id="cosmeticFilteringDialog" class="modalDialog">
         <textarea class="cosmeticFilters"></textarea>
-        <button id="createCosmeticFilters" class="important" type="button" data-i18n="pickerCreate"></button>
+        <button id="createCosmeticFilters" class="preferred" type="button" data-i18n="pickerCreate"></button>
     </div>
 
     <div id="loggerStatsDialog">