Update static/index.html

static/index.html

@@ -48,6 +48,7 @@
                 <label>Deflection Strength: <input type="range" id="fluid-deflection" min="0" max="0.5" step="0.01" value="0.1"></label>
             </div>
             <button id="start-btn">Start Simulation</button>
+            <button id="stop-btn">Stop Simulation</button>
             <button id="reset-btn">Reset Simulation</button>
             <button id="save-btn">Save Settings</button>
             <button id="load-btn">Load Settings</button>