modify: extend common config

Author: sota1235

browser/main/modals/PreferencesModal/ConfigTab.styl

@@ -1,14 +1,15 @@
+@import('./Tab')
+
 .root
   padding 15px
   color $ui-text-color
+
 .group
   margin-bottom 45px
+
 .group-header
-  font-size 24px
+  @extend .header
   color $ui-text-color
-  padding 5px
-  border-bottom $default-border
-  margin-bottom 15px
 
 .group-header2
   font-size 18px