Update nutri_call.html

nutri_call.html

@@ -593,9 +593,11 @@ legend {
                     <div class="column-header">NH4</div>
                     <div class="nitrogen-group">
                         <input id="profile_nh4" type="number" value="1.0" step="1.0" readonly style="background-color: #f0f0f0; color: #666;">
+        <button class="square-button" id="minus-button" style="font-weight: bold;">-</button>
                     </div>
                     <div class="nitrogen-group">
                         <input id="calculated_nh4" type="number" value="0.000" step="0.001" readonly style="background-color: #f0f0f0; color: #666;">
+        <button class="square-button" id="plus-button" style="font-weight: bold;">+</button>
                     </div>
                 </div>