fix: 컨텐츠 영역 중앙정렬

Author: lgrin-byte

app/admin/(style)/admin.modules.sass

@@ -130,6 +130,7 @@
   border-radius: 8px
 
 .content-area
+  margin: 0 auto
   flex-grow: 1
   flex-shrink: 1
   overflow-x: hidden