feat: 테이블 테두리 및 라운드 제거, 검색 필터 제목 제거

- 모든 테이블 컴포넌트의 외곽 테두리(border) 제거
- 테이블 컨테이너의 라운드(rounded-lg) 제거
- 테이블 행 구분선(border-b)은 유지하여 데이터 구분
- FlowWidget과 TableListComponent에 동일한 스타일 적용
- 검색 필터 영역의 회색 배경(bg-muted/30) 제거
- 검색 필터 제목 제거
- AdvancedSearchFilters 컴포넌트의 '검색 필터' 제목 제거

frontend/components/screen/ScreenPreview.tsx

@@ -29,9 +29,9 @@ export default function ScreenPreview({ layout, screenName, className }: ScreenP
       case "desktop":
         return "w-full max-w-6xl mx-auto";
       case "tablet":
-        return "w-full max-w-2xl mx-auto border-x-8 border-gray-200";
+        return "w-full max-w-2xl mx-auto border-x-8 border-border";
       case "mobile":
-        return "w-full max-w-sm mx-auto border-x-4 border-gray-200";
+        return "w-full max-w-sm mx-auto border-x-4 border-border";
       default:
         return "w-full";
     }
@@ -100,7 +100,7 @@ export default function ScreenPreview({ layout, screenName, className }: ScreenP
 
     return (
       <div
-        className="min-h-screen bg-white"
+        className="min-h-screen bg-background"
         style={{
           padding: `${padding}px`,
         }}
@@ -135,12 +135,12 @@ export default function ScreenPreview({ layout, screenName, className }: ScreenP
       {/* 미리보기 헤더 */}
       <Card>
         <CardHeader className="pb-3">
-          <div className="flex items-center justify-between">
-            <CardTitle className="flex items-center gap-2 text-sm font-medium">
+          <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+            <CardTitle className="flex items-center gap-2 text-sm font-medium sm:text-base">
               <Eye className="h-4 w-4" />
               {screenName} - 미리보기
             </CardTitle>
-            <div className="flex items-center gap-2">
+            <div className="flex flex-wrap items-center gap-2">
               {/* 미리보기 모드 선택 */}
               <div className="flex rounded-lg border">
                 <Button
@@ -183,13 +183,13 @@ export default function ScreenPreview({ layout, screenName, className }: ScreenP
       {/* 미리보기 컨텐츠 */}
       <Card>
         <CardContent className="p-0">
-          <div className={`${getPreviewStyles(previewMode)} min-h-screen bg-gray-50`}>
+          <div className={`${getPreviewStyles(previewMode)} min-h-screen bg-muted`}>
             {layout.components.length > 0 ? (
               renderGridLayout()
             ) : (
-              <div className="flex min-h-screen items-center justify-center text-gray-500">
+              <div className="flex min-h-screen items-center justify-center text-muted-foreground">
                 <div className="text-center">
-                  <Eye className="mx-auto mb-4 h-16 w-16 text-gray-300" />
+                  <Eye className="mx-auto mb-4 h-16 w-16 text-muted-foreground/30" />
                   <p>미리보기할 컴포넌트가 없습니다</p>
                   <p className="text-sm">화면 설계기에서 컴포넌트를 추가해주세요</p>
                 </div>