De-duplicate puzzle and round blindfold style

ui/puzzle/css/_puzzle.scss

@@ -9,4 +9,3 @@ $puzzle-history-height: $col3-uniboard-controls;
 @import 'tools';
 @import 'history';
 @import 'after';
-@import 'blindfold';

ui/puzzle/css/build/_puzzle.scss

@@ -12,5 +12,6 @@
 @import '../../../chess/css/opening';
 @import '../../../chess/css/control';
 @import '../../../chess/css/promotion';
+@import '../../../chess/css/blindfold';
 
 @import '../puzzle';

ui/round/css/_blindfold.scss

@@ -1,9 +0,0 @@
-.blindfold {
-  &.main-board piece,
-  .now-playing piece {
-    opacity: 0;
-  }
-  &.main-board .check {
-    background: none;
-  }
-}

ui/round/css/_round.scss

@@ -20,5 +20,4 @@ $move-tag: 'm2';
 @import 'icon';
 @import 'now-playing';
 @import 'keyboard-move';
-@import 'blindfold';
 @import 'forecast-info';

ui/round/css/build/_round.scss

@@ -12,6 +12,7 @@
 @import '../../../common/css/form/cmn-toggle';
 @import '../../../chess/css/variant-style';
 @import '../../../chess/css/promotion';
+@import '../../../chess/css/blindfold';
 @import '../../../chat/css/chat';
 @import '../../../chat/css/preset';
 @import '../round';