요소 헤더 배경을 투명하게 변경

frontend/components/admin/dashboard/CanvasElement.tsx

@@ -543,7 +543,7 @@ export function CanvasElement({
       onMouseDown={handleMouseDown}
     >
       {/* 헤더 */}
-      <div className="flex cursor-move items-center justify-between border-b border-gray-200 bg-gray-50 p-3">
+      <div className="flex cursor-move items-center justify-between p-3">
         <span className="text-sm font-bold text-gray-800">{element.customTitle || element.title}</span>
         <div className="flex gap-1">
           {/* 설정 버튼 (기사관리 위젯만 자체 설정 UI 사용) */}