diff --git a/src/databrowser.html b/src/databrowser.html
index 716cfd79..c80050ef 100644
--- a/src/databrowser.html
+++ b/src/databrowser.html
@@ -31,13 +31,13 @@
     -->
 
     <!-- Main content area — single visible region at a time -->
-    <main id="MainContent" role="main" tabindex="-1" aria-live="polite">
+    <div tabindex="-1" aria-live="polite">
       <div class="app-shell">
         <aside id="NavMenu" class="app-nav" aria-label="Application menu" hidden>
           <div id="NavMenuContent" class="menu-content"></div>
         </aside>
 
-        <div class="app-view">
+        <main id="MainContent" class="app-view">
           <!--
             Outline view: the primary RDF-subject browser.
             JS appends property-table <div>s (not <tr>s) here.
@@ -66,11 +66,11 @@
           >
           <!-- globalAppTabs appends tab widget here -->
           </section>
-        </div> <!-- .app-view -->
+        </main> <!-- .app-view -->
       </div> <!-- .app-shell -->
 
       <div id="MenuOverlay" class="menu-overlay" hidden aria-hidden="true"></div>
-    </main>
+    </div>
 
     <!-- Footer — populated by solid-ui initFooter() -->
     <footer id="PageFooter" role="contentinfo">
diff --git a/src/styles/mash.css b/src/styles/mash.css
index 46f93ffe..39b8ca0e 100644
--- a/src/styles/mash.css
+++ b/src/styles/mash.css
@@ -41,11 +41,11 @@ html, body {
 
 #MainContent {
   flex: 1 1 auto;
+  min-width: 0;
   min-height: 0;
   overflow-y: auto;
   -webkit-overflow-scrolling: touch;   /* smooth iOS scroll */
   container-type: inline-size;          /* enable @container queries */
-  display: flex;
 }
 
 #PageFooter {
@@ -56,7 +56,7 @@ html, body {
 /* ── New responsive app nav layout ── */
 .app-shell {
   display: flex;
-  flex: 1;          /* expand to fill #MainContent (display:flex row container) */
+  flex: 1;          /* expand to fill .app-shell row */
   min-width: 0;     /* prevent overflow in flex context */
   min-height: calc(100vh - var(--app-header-height) - 2.5rem); /* header + footer space */
   margin-top: var(--app-header-height);
diff --git a/static/browse-test.html b/static/browse-test.html
index c5559972..d45cd98d 100644
--- a/static/browse-test.html
+++ b/static/browse-test.html
@@ -117,7 +117,7 @@
     As user <span id="webId">&lt;public user></span> 
     <span id="loginButtonArea"></span>
   </div>
-  <main id="MainContent" role="main" tabindex="-1" aria-live="polite" class="browser-main">
+  <main id="MainContent" tabindex="-1" aria-live="polite" class="browser-main">
 
     <table
           id="OutlineView"
diff --git a/static/browse.html b/static/browse.html
index eaf4f292..a07ecb32 100644
--- a/static/browse.html
+++ b/static/browse.html
@@ -117,7 +117,7 @@
     As user <span id="webId">&lt;public user></span> 
     <span id="loginButtonArea"></span>
   </div>
-  <main id="MainContent" role="main" tabindex="-1" aria-live="polite" class="browser-main">
+  <main id="MainContent" tabindex="-1" aria-live="polite" class="browser-main">
 
     <table
           id="OutlineView"