diff --git a/web/src/Shell.tsx b/web/src/Shell.tsx
index ff6269f..bc38b74 100644
--- a/web/src/Shell.tsx
+++ b/web/src/Shell.tsx
@@ -155,8 +155,13 @@ export default function Shell({
             <div className="tk-account-anon-badge" title="Unauthenticated: only the public corpus is searchable">
               Browsing the public docs
             </div>
-            <button type="button" className="tk-btn tk-btn-secondary tk-account-signin" onClick={onLogout}>
-              Sign in
+            <button type="button" className="tk-btn tk-btn-secondary tk-account-signin" onClick={onLogout}
+                    title="Sign in" aria-label="Sign in">
+              <svg className="tk-nav-icon" viewBox="0 0 24 24" fill="none" stroke="currentColor"
+                   strokeWidth={1.8} strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+                <path d="M15 3h4a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2h-4M10 17l5-5-5-5M15 12H3" />
+              </svg>
+              <span className="tk-account-signin-label">Sign in</span>
             </button>
           </div>
         ) : (
diff --git a/web/src/app.css b/web/src/app.css
index 58bf652..9886a9a 100644
--- a/web/src/app.css
+++ b/web/src/app.css
@@ -909,6 +909,11 @@ h2 { font-size: 14px; font-weight: 600; margin-top: 24px; color: var(--gray-200)
 .tk-account-anonymous { display: flex; flex-direction: column; gap: 8px; padding: 8px 4px; }
 .tk-account-anon-badge { font-size: 12px; color: var(--gray-500); }
 .tk-sidebar.collapsed .tk-account-anon-badge { display: none; }
-.tk-account-signin { width: 100%; }
+.tk-account-signin { width: 100%; display: inline-flex; align-items: center; justify-content: center; gap: 6px; }
+.tk-account-signin .tk-nav-icon { width: 16px; height: 16px; }
+/* Collapsed sidebar (56px): icon only, the label moves to the tooltip. */
+.tk-sidebar.collapsed .tk-account-signin { width: 40px; padding: 8px 0; margin: 0 auto; }
+.tk-sidebar.collapsed .tk-account-signin-label { display: none; }
+.tk-sidebar.collapsed .tk-account-anonymous { padding: 8px 0; align-items: center; }
 .tk-form-warning { color: var(--red-500); }