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+# Mobile Bottom Tab Bar Verification (bf-om23)
+
+## Finding
+
+The mobile bottom tab bar specified in §16.4 **IS implemented**, but its styles are located in `web/index.html` as inline styles rather than in the external CSS files (`base.css`, `mobile.css`, `components.css`).
+
+## Implementation Location
+
+**HTML Structure** (`web/index.html` lines 898-918):
+```html
+<!-- Mobile bottom tab bar -->
+<div class="mobile-bottom-nav">
+  <div class="nav-links">
+    <a href="#/" class="nav-link">
+      <span>🏠</span>
+      <span>Home</span>
+    </a>
+    <a href="#/watch" class="nav-link">
+      <span>👀</span>
+      <span>Watch</span>
+    </a>
+    <a href="#/compete" class="nav-link">
+      <span>⚔️</span>
+      <span>Compete</span>
+    </a>
+    <a href="#/leaderboard" class="nav-link">
+      <span>🏆</span>
+      <span>Board</span>
+    </a>
+  </div>
+</div>
+```
+
+**CSS Styles** (`web/index.html` lines 158-182, 229-236):
+```css
+/* Mobile bottom tab bar */
+.mobile-bottom-nav {
+  display: none;
+  position: fixed;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  background-color: var(--bg-secondary);
+  border-top: 1px solid var(--border);
+  padding: 8px 0;
+  z-index: 100;
+}
+
+.mobile-bottom-nav .nav-links {
+  justify-content: space-around;
+  width: 100%;
+}
+
+.mobile-bottom-nav .nav-link {
+  flex-direction: column;
+  padding: 6px 12px;
+  font-size: 0.75rem;
+  text-align: center;
+}
+
+/* Responsive */
+@media (max-width: 639px) {
+  /* Show bottom tab bar */
+  .mobile-bottom-nav {
+    display: block;
+  }
+
+  /* Add padding to bottom of main content for bottom nav */
+  #app {
+    padding-bottom: 70px;
+  }
+}
+```
+
+## External CSS References
+
+The external CSS files reference `.mobile-bottom-nav` but do NOT define its styles:
+
+- **`mobile.css` line 616**: Hides `.mobile-bottom-nav` on desktop (>1024px)
+- **`mobile.css` line 711-718**: Minimal padding adjustments in landscape mode
+- **`mobile.css` line 6**: Comment mentioning "bottom tab bar"
+
+## Specification Compliance
+
+The implementation matches §16.4 of the plan:
+- Four bottom tabs: Home, Watch, Compete, Board
+- Persistent bottom tab bar on mobile (<640px)
+- Thumb-reachable, always visible
+- Hidden on desktop/tablet
+- Proper z-index layering (z-index: 100)
+
+## Conclusion
+
+**Status**: The mobile bottom tab bar is fully implemented and functional. The styles are inline in `index.html` rather than in external CSS files, which is a valid (though less modular) approach.
+
+**Recommendation**: If desired for better code organization, the inline styles could be moved to `mobile.css`, but this is not necessary for functionality.