diff --git a/src/app/components/AppHeader.tsx b/src/app/components/AppHeader.tsx
index a46e6df..9fd1f5f 100644
--- a/src/app/components/AppHeader.tsx
+++ b/src/app/components/AppHeader.tsx
@@ -21,11 +21,16 @@ export function AppHeader() {
   const panelRef = React.useRef<HTMLDivElement | null>(null);
   const blockRefs = React.useRef<Record<string, HTMLDivElement | null>>({});
   const navItemRefs = React.useRef<Record<string, HTMLDivElement | null>>({});
+  const navRowRef = React.useRef<HTMLDivElement | null>(null);
+  const navTextRefs = React.useRef<Record<string, HTMLSpanElement | null>>({});
   const [leftPositions, setLeftPositions] = React.useState<Record<string, number>>({});
   const [panelHeight, setPanelHeight] = React.useState<number>(0);
   const [blockWidths, setBlockWidths] = React.useState<Record<string, number>>({});
   const closeTimer = React.useRef<number | null>(null);
   const [navMinWidths, setNavMinWidths] = React.useState<Record<string, number>>({});
+  const [indicatorLeft, setIndicatorLeft] = React.useState<number>(0);
+  const [indicatorWidth, setIndicatorWidth] = React.useState<number>(0);
+  const [indicatorVisible, setIndicatorVisible] = React.useState<boolean>(false);
   // 모바일 사이드바 열릴 때만 현재 사용자 정보를 가져옵니다(훅은 항상 동일한 순서로 호출)
   const { data: meData } = useSWR<{ user: { userId: string; nickname: string; profileImage: string | null; points: number; level: number; grade: number } | null }>(
     mobileOpen ? "/api/me" : null,
@@ -80,6 +85,40 @@ export function AppHeader() {
     return () => window.removeEventListener("categories:reload", onRefresh);
   }, [reloadCategories]);
 
+  // 상단 네비게이션 선택/호버 인디케이터 업데이트
+  const updateIndicator = React.useCallback(() => {
+    const container = navRowRef.current;
+    if (!container) return;
+    const targetSlug = (megaOpen && openSlug) ? openSlug : activeCategorySlug;
+    if (!targetSlug) {
+      setIndicatorVisible(false);
+      return;
+    }
+    const itemEl = navItemRefs.current[targetSlug];
+    if (!itemEl) {
+      setIndicatorVisible(false);
+      return;
+    }
+    const cr = container.getBoundingClientRect();
+    const ir = itemEl.getBoundingClientRect();
+    const inset = 0; // 컨테이너(div) 너비 기준
+    const nextLeft = Math.max(0, ir.left - cr.left + inset);
+    const nextWidth = Math.max(0, ir.width - inset * 2);
+    setIndicatorLeft(nextLeft);
+    setIndicatorWidth(nextWidth);
+    setIndicatorVisible(true);
+  }, [megaOpen, openSlug, activeCategorySlug]);
+
+  React.useEffect(() => {
+    updateIndicator();
+  }, [updateIndicator, categories]);
+
+  React.useEffect(() => {
+    const onResize = () => updateIndicator();
+    window.addEventListener("resize", onResize);
+    return () => window.removeEventListener("resize", onResize);
+  }, [updateIndicator]);
+
   // ESC로 메가메뉴 닫기
   React.useEffect(() => {
     if (!megaOpen) return;
@@ -302,7 +341,12 @@ export function AppHeader() {
     };
   }, []);
   return (
-    <header ref={headerRef} className="relative flex items-center justify-between px-4 py-3  bg-white/80 backdrop-blur supports-[backdrop-filter]:bg-white/60">
+    <header
+      ref={headerRef}
+      className={`relative flex items-center justify-between px-4 py-3 bg-white/80 backdrop-blur supports-[backdrop-filter]:bg-white/60 ${
+        megaOpen ? "shadow-[0_6px_24px_rgba(0,0,0,0.10)]" : ""
+      }`}
+    >
       <div className="flex items-center gap-3 z-[100]">
         <button
           aria-label="메뉴 열기"
@@ -333,7 +377,7 @@ export function AppHeader() {
             if (!e.currentTarget.contains(next)) setMegaOpen(false);
           }}
         >
-          <div className="flex items-center gap-8">
+          <div className="relative flex items-center gap-8" ref={navRowRef}>
             {categories.map((cat, idx) => (
               <div
                 key={cat.id}
@@ -342,31 +386,44 @@ export function AppHeader() {
                 ref={(el) => {
                   navItemRefs.current[cat.slug] = el;
                 }}
-                style={idx === categories.length - 1 ? { minWidth: 120 } : undefined}
               >
                 <Link
                   href={cat.boards?.[0]?.slug ? `/boards/${cat.boards[0].slug}` : `/boards?category=${cat.slug}`}
-                  className={`block w-full px-2 py-2 text-sm font-medium transition-colors duration-200 hover:text-neutral-900 whitespace-nowrap ${
-                    activeCategorySlug === cat.slug ? "text-neutral-900" : "text-neutral-700"
+                  className={`block w-full px-2 py-2 text-sm font-medium transition-colors duration-200 whitespace-nowrap ${
+                    (megaOpen && openSlug === cat.slug) || activeCategorySlug === cat.slug ? "" : "text-neutral-700"
                   }`}
+                  style={(megaOpen && openSlug === cat.slug) || activeCategorySlug === cat.slug ? { color: "var(--red-50, #F94B37)" } : undefined}
                   ref={(el) => {
                     navRefs.current[cat.slug] = el;
                   }}
                 >
-                  {cat.name}
+                  <span
+                    ref={(el) => {
+                      navTextRefs.current[cat.slug] = el;
+                    }}
+                    className="inline-block"
+                  >
+                    {cat.name}
+                  </span>
                 </Link>
-                <span
-                  className={`pointer-events-none absolute left-1 right-1 -bottom-0.5 h-0.5 origin-left rounded bg-neutral-900 transition-all duration-200 ${
-                    (megaOpen && openSlug === cat.slug) || activeCategorySlug === cat.slug
-                      ? "scale-x-100 opacity-100"
-                      : "scale-x-0 opacity-0 group-hover:opacity-100 group-hover:scale-x-100"
-                  }`}
-                />
               </div>
             ))}
+            {/* 공용 선택 인디케이터 바 (Figma 스타일) */}
+            <span
+              aria-hidden
+              className="pointer-events-none absolute bottom-0 left-0 transition-all duration-300 ease-out"
+              style={{
+                transform: `translateX(${indicatorLeft}px)`,
+                width: indicatorWidth,
+                height: 4,
+                opacity: indicatorVisible ? 1 : 0,
+                background: "var(--red-50, #F94B37)",
+                borderRadius: "var(--radius-24, 24px) var(--radius-24, 24px) 0 0",
+              }}
+            />
           </div>
           <div
-            className={`fixed left-0 right-0 z-50 border-t bg-white shadow-[0_8px_24px_rgba(0,0,0,0.08)] transition-all duration-200 ${
+            className={`fixed left-0 right-0 z-50 bg-white shadow-[0_12px_32px_rgba(0,0,0,0.12)] transition-all duration-200 ${
               megaOpen ? "opacity-100" : "pointer-events-none opacity-0"
             }`}
             style={{ top: headerBottom }}
@@ -390,9 +447,10 @@ export function AppHeader() {
                         <Link
                           key={b.id}
                           href={`/boards/${b.slug}`}
-                          className={`rounded px-2 py-1 text-sm transition-colors duration-150 hover:bg-neutral-100 hover:text-neutral-900 text-center whitespace-nowrap ${
-                            activeBoardId === b.slug ? "bg-neutral-100 text-neutral-900 font-medium" : "text-neutral-700"
+                          className={`rounded px-2 py-1 text-sm transition-colors duration-150 text-center whitespace-nowrap ${
+                            activeBoardId === b.slug ? "font-semibold" : "text-neutral-700 hover:text-neutral-900 hover:bg-neutral-100"
                           }`}
+                          style={activeBoardId === b.slug ? { color: "var(--red-50, #F94B37)" } : undefined}
                           aria-current={activeBoardId === b.slug ? "page" : undefined}
                         >
                           {b.name}