Update index.html

index.html

@@ -149,7 +149,7 @@ in this demonstration.  Multiple Bin numbers are also support</p>
     </div>
     <div class="slider-container">
       <div class="slider-label"><span>Gradient Threshold</span></div>
-      <div class="slider-content" id="gradsient-norm-slider"><div id="gradient-norm-threshold" class="slider-value ui-slider-handle"></div></div>
+      <div class="slider-content" id="gradient-norm-slider"><div id="gradient-norm-threshold" class="slider-value ui-slider-handle"></div></div>
     </div>
     <figcaption class="figure-caption">
     </figcaption>