diff --git a/src/components/Layout.tsx b/src/components/Layout.tsx
index 417c9f7..879097b 100644
--- a/src/components/Layout.tsx
+++ b/src/components/Layout.tsx
@@ -37,7 +37,7 @@ export function Layout({ children, stats }: LayoutProps) {
       }}
     >
       {/* Top bar */}
-      <div
+      <header
         style={{
           borderBottom: '1px solid var(--color-border)',
         }}
@@ -184,9 +184,9 @@ export function Layout({ children, stats }: LayoutProps) {
             </button>
           </div>
         </div>
-      </div>
+      </header>
 
-      <div
+      <main
         style={{
           maxWidth: 860,
           margin: '0 auto',
@@ -220,33 +220,38 @@ export function Layout({ children, stats }: LayoutProps) {
 
         {/* Page content */}
         {children}
-      </div>
+      </main>
 
       {/* Fixed bottom-left attribution */}
-      <a
-        href="https://nullrabbit.ai"
-        target="_blank"
-        rel="noopener noreferrer"
+      <footer
         style={{
           position: 'fixed',
           bottom: isMobile ? 16 : 24,
           left: isMobile ? 16 : 24,
-          display: 'flex',
-          alignItems: 'center',
-          gap: 5,
-          color: 'var(--color-text-dim)',
-          textDecoration: 'none',
-          fontSize: 10,
-          fontFamily: "'JetBrains Mono', monospace",
           zIndex: 100,
         }}
       >
-        <img
-          src="/nullrabbit.png"
-          alt="NullRabbit"
-          style={{ height: 22, width: 22, objectFit: 'contain' }}
-        />
-      </a>
+        <a
+          href="https://nullrabbit.ai"
+          target="_blank"
+          rel="noopener noreferrer"
+          style={{
+            display: 'flex',
+            alignItems: 'center',
+            gap: 5,
+            color: 'var(--color-text-dim)',
+            textDecoration: 'none',
+            fontSize: 10,
+            fontFamily: "'JetBrains Mono', monospace",
+          }}
+        >
+          <img
+            src="/nullrabbit.png"
+            alt="NullRabbit"
+            style={{ height: 22, width: 22, objectFit: 'contain' }}
+          />
+        </a>
+      </footer>
 
       <WaitlistDrawer />
     </div>
diff --git a/src/components/TabBar.tsx b/src/components/TabBar.tsx
index de87f15..b51c4bf 100644
--- a/src/components/TabBar.tsx
+++ b/src/components/TabBar.tsx
@@ -15,7 +15,7 @@ export function TabBar() {
   const { pathname } = useLocation();
   const isMobile = useIsMobile();
   const [open, setOpen] = useState(false);
-  const containerRef = useRef<HTMLDivElement>(null);
+  const containerRef = useRef<HTMLElement>(null);
 
   const currentTab = TABS.find(t => t.path === pathname) ?? TABS[0];
 
@@ -53,7 +53,7 @@ export function TabBar() {
   // Desktop: horizontal tab bar (unchanged)
   if (!isMobile) {
     return (
-      <div
+      <nav
         style={{
           display: 'flex',
           gap: 0,
@@ -86,13 +86,13 @@ export function TabBar() {
             </Link>
           );
         })}
-      </div>
+      </nav>
     );
   }
 
   // Mobile: dropdown trigger + menu
   return (
-    <div ref={containerRef} style={{ position: 'relative', marginBottom: 12 }}>
+    <nav ref={containerRef} style={{ position: 'relative', marginBottom: 12 }}>
       <button
         onClick={() => setOpen(prev => !prev)}
         aria-expanded={open}
@@ -172,6 +172,6 @@ export function TabBar() {
           })}
         </div>
       )}
-    </div>
+    </nav>
   );
 }
diff --git a/src/components/ValidatorProfile.tsx b/src/components/ValidatorProfile.tsx
index dbdde19..3c70cfc 100644
--- a/src/components/ValidatorProfile.tsx
+++ b/src/components/ValidatorProfile.tsx
@@ -70,6 +70,7 @@ function computeVerdict(events: ValidatorEventItem[]): Verdict {
 
 const sectionHeadingStyle: React.CSSProperties = {
   fontSize: 12,
+  fontWeight: 400,
   color: 'var(--color-text-heading)',
   fontFamily: "'JetBrains Mono', monospace",
   textTransform: 'uppercase',
@@ -658,7 +659,7 @@ export function ValidatorProfile() {
               : 'var(--color-danger)';
         return (
           <div style={{ marginBottom: 24, paddingBottom: 24, borderBottom: '1px solid var(--color-border)' }}>
-            <div style={sectionHeadingStyle}>Reliability</div>
+            <h2 style={sectionHeadingStyle}>Reliability</h2>
             <div style={{ marginTop: 12 }}>
               <div style={metaLabelStyle}>Delinquency</div>
               <div style={{ ...metaValueStyle, color }}>
@@ -673,9 +674,9 @@ export function ValidatorProfile() {
       {chainData && <ChainDataSections chainData={chainData} isMobile={isMobile} />}
 
       {/* Event history header */}
-      <div style={sectionHeadingStyle}>
+      <h2 style={sectionHeadingStyle}>
         event history
-      </div>
+      </h2>
 
       {titleGroups.length === 0 ? (
         <div
@@ -865,9 +866,9 @@ export function ValidatorProfile() {
       {/* Infrastructure section */}
       {showInfrastructure && (
         <div style={{ marginTop: 32 }}>
-          <div style={sectionHeadingStyle}>
+          <h2 style={sectionHeadingStyle}>
             infrastructure
-          </div>
+          </h2>
 
           <div
             style={
diff --git a/src/pages/LeaderboardPage.tsx b/src/pages/LeaderboardPage.tsx
index 33677c4..0d371c0 100644
--- a/src/pages/LeaderboardPage.tsx
+++ b/src/pages/LeaderboardPage.tsx
@@ -77,9 +77,10 @@ export default function LeaderboardPage() {
   return (
     <div style={{ marginTop: 8 }}>
       {/* Heading */}
-      <div
+      <h2
         style={{
           fontSize: 11,
+          fontWeight: 400,
           fontFamily: "'JetBrains Mono', monospace",
           textTransform: 'uppercase',
           letterSpacing: '0.08em',
@@ -88,17 +89,17 @@ export default function LeaderboardPage() {
         }}
       >
         {sort === 'worst' ? 'Worst Offenders' : 'Most Reliable'}
-      </div>
-      <div
+      </h2>
+      <p
         style={{
           fontSize: 12,
           fontFamily: "'Inter', sans-serif",
           color: 'var(--color-text-tertiary)',
-          marginBottom: 16,
+          margin: '0 0 16px',
         }}
       >
         Validators ranked by incident severity over {periodLabel}
-      </div>
+      </p>
 
       {/* Controls */}
       <div style={{ display: 'flex', flexWrap: 'wrap', gap: isMobile ? 6 : 8, marginBottom: 16, alignItems: 'center' }}>
diff --git a/src/pages/ReportsPage.tsx b/src/pages/ReportsPage.tsx
index d414c59..b2b3a2e 100644
--- a/src/pages/ReportsPage.tsx
+++ b/src/pages/ReportsPage.tsx
@@ -59,9 +59,10 @@ export default function ReportsPage() {
 
   return (
     <div>
-      <div
+      <h2
         style={{
           fontSize: 11,
+          fontWeight: 400,
           fontFamily: monoFont,
           textTransform: 'uppercase',
           letterSpacing: '0.08em',
@@ -70,7 +71,7 @@ export default function ReportsPage() {
         }}
       >
         Provider Reliability Reports
-      </div>
+      </h2>
 
       {/* Search input */}
       <input