diff --git a/index.html b/index.html
index a98f8ca..67a8bb4 100644
--- a/index.html
+++ b/index.html
@@ -71,9 +71,40 @@
             <span class="user-dot" aria-hidden="true"></span>
             <span class="user-text" id="userText">로그인 필요</span>
           </div>
-          <button class="btn" id="btnGoogle" type="button" hidden>구글</button>
-          <button class="btn" id="btnKakao" type="button" hidden>카카오</button>
-          <button class="btn" id="btnNaver" type="button" hidden>네이버</button>
+          <button class="btn icon-only provider-google" id="btnGoogle" type="button" hidden aria-label="구글로 로그인">
+            <span class="sr-only">구글</span>
+            <svg viewBox="0 0 24 24" aria-hidden="true">
+              <path
+                fill="#EA4335"
+                d="M12 10.2v3.9h5.45c-.24 1.26-1.44 3.7-5.45 3.7-3.28 0-5.96-2.72-5.96-6.1S8.72 5.6 12 5.6c1.87 0 3.12.8 3.84 1.5l2.62-2.52C16.86 3.08 14.7 2 12 2 6.48 2 2 6.48 2 11.7S6.48 21.4 12 21.4c6.92 0 9.6-4.86 9.6-7.38 0-.5-.06-.88-.13-1.26H12z"
+              />
+              <path
+                fill="#34A853"
+                d="M3.15 7.55l3.21 2.36C7.2 7.7 9.38 5.6 12 5.6c1.87 0 3.12.8 3.84 1.5l2.62-2.52C16.86 3.08 14.7 2 12 2 8.16 2 4.84 4.1 3.15 7.55z"
+                opacity=".0"
+              />
+            </svg>
+          </button>
+          <button class="btn icon-only provider-kakao" id="btnKakao" type="button" hidden aria-label="카카오로 로그인">
+            <span class="sr-only">카카오</span>
+            <svg viewBox="0 0 24 24" aria-hidden="true">
+              <path
+                fill="#FAE100"
+                d="M12 3C6.76 3 2.5 6.23 2.5 10.22c0 2.58 1.78 4.85 4.45 6.12l-1.01 3.69a.7.7 0 0 0 1.05.77l4.3-2.85c.55.05 1.11.08 1.66.08 5.24 0 9.5-3.23 9.5-7.22C21.5 6.23 17.24 3 12 3z"
+              />
+              <path
+                fill="#000"
+                d="M12 6.4c-3.7 0-6.7 2.2-6.7 4.9S8.3 16.2 12 16.2s6.7-2.2 6.7-4.9-3-4.9-6.7-4.9z"
+                opacity=".08"
+              />
+            </svg>
+          </button>
+          <button class="btn icon-only provider-naver" id="btnNaver" type="button" hidden aria-label="네이버로 로그인">
+            <span class="sr-only">네이버</span>
+            <svg viewBox="0 0 24 24" aria-hidden="true">
+              <path fill="#03C75A" d="M6 4h5.1l6.9 10.1V4H18v16h-5.1L6 9.9V20H6V4z" />
+            </svg>
+          </button>
           <button class="btn" id="btnLogin" type="button">로그인</button>
           <button class="btn" id="btnLogout" type="button" hidden>로그아웃</button>
         </div>
diff --git a/script.js b/script.js
index 4a05208..927bfda 100644
--- a/script.js
+++ b/script.js
@@ -448,7 +448,8 @@
     // 로그인 기능이 활성(enabled)일 때만 로그인/로그아웃 버튼을 의미 있게 노출
     const enabled = auth.mode === "enabled";
     el.btnLogin.hidden = enabled ? Boolean(auth.user) : false;
-    el.btnLogout.hidden = !(enabled && auth.user);
+    // 로그아웃은 로그인 된 이후에만 노출
+    el.btnLogout.hidden = !auth.user;
     // 설정/SDK 문제 상태에서도 버튼은 "클릭 가능"하게 두고, 클릭 시 토스트로 안내합니다.
     el.btnLogin.disabled = false;
     el.btnLogout.disabled = false;
diff --git a/styles.css b/styles.css
index f594daf..9040c97 100644
--- a/styles.css
+++ b/styles.css
@@ -35,6 +35,11 @@ html[data-theme="light"] {
   box-sizing: border-box;
 }
 
+/* Ensure HTML hidden attribute always works (avoid .btn overriding it) */
+[hidden] {
+  display: none !important;
+}
+
 body {
   margin: 0;
   font-family: var(--sans);
@@ -138,6 +143,43 @@ html[data-theme="light"] .topbar {
   justify-content: flex-end;
 }
 
+.sr-only {
+  position: absolute !important;
+  width: 1px !important;
+  height: 1px !important;
+  padding: 0 !important;
+  margin: -1px !important;
+  overflow: hidden !important;
+  clip: rect(0, 0, 0, 0) !important;
+  white-space: nowrap !important;
+  border: 0 !important;
+}
+
+.btn.icon-only {
+  width: 40px;
+  height: 40px;
+  padding: 0;
+  justify-content: center;
+  gap: 0;
+}
+
+.btn.icon-only svg {
+  width: 18px;
+  height: 18px;
+}
+
+.btn.provider-google {
+  border-color: rgba(66, 133, 244, 0.25);
+}
+
+.btn.provider-kakao {
+  border-color: rgba(250, 225, 0, 0.35);
+}
+
+.btn.provider-naver {
+  border-color: rgba(3, 199, 90, 0.28);
+}
+
 .user {
   display: inline-flex;
   align-items: center;