diff --git a/dicom-viewer/src/App.tsx b/dicom-viewer/src/App.tsx
index 93fbcec..cdfaa4c 100644
--- a/dicom-viewer/src/App.tsx
+++ b/dicom-viewer/src/App.tsx
@@ -2555,6 +2555,39 @@ function App({ container_id, imageStacks, autoCacheStack, annotationJson, viewer
                 }}
                 onClick={e => e.stopPropagation()} // <-- prevent bubbling to viewport
               >
+                <button
+                  style={{
+                    display: "block",
+                    width: "100%",
+                    margin: "2px 0 8px 0",
+                    background: "#444",
+                    color: "#fff",
+                    border: "none",
+                    borderRadius: "3px",
+                    cursor: "pointer",
+                    padding: "6px 0",
+                    fontSize: "13px",
+                    fontWeight: "600",
+                  }}
+                  onClick={(e) => {
+                    e.stopPropagation();
+                    // Reset viewport properties (window/level and camera) to defaults
+                    try {
+                      const viewportId = `CT_${i}`;
+                      const renderingEngine = renderingEngineRef.current;
+                      const viewport = renderingEngine?.getViewport(viewportId);
+                      if (viewport) {
+                        if (typeof viewport.resetProperties === 'function') viewport.resetProperties();
+                        if (typeof viewport.resetCamera === 'function') viewport.resetCamera();
+                        if (typeof viewport.render === 'function') viewport.render();
+                        updateOverlay(i, viewport);
+                      }
+                    } catch (err) { console.warn('Failed to reset viewport properties', err); }
+                    setPresetsOpenArr(prev => { const next = [...prev]; next[i] = false; return next; });
+                  }}
+                >
+                  Reset to default
+                </button>
                 {WINDOW_LEVEL_PRESETS.map((preset) => (
                   <button
                     key={preset.name}