diff --git a/animations/heap/sort/heap-sort.js b/animations/heap/sort/heap-sort.js
index 0fa1fbf..a0d39c1 100644
--- a/animations/heap/sort/heap-sort.js
+++ b/animations/heap/sort/heap-sort.js
@@ -1,5 +1,3 @@
-//AUTHOR: Chloe Lee
-
 // initial array to be sorted
 let array = [5, 3, 8, 1, 9, 4];
 let currentStep = 0;
@@ -32,7 +30,6 @@ const codeLines = [
 ];
 
 function initialize() {
-  // Display code with line numbers
   const codeElement = document.getElementById('code');
   let codeHTML = '';
   
@@ -106,6 +103,8 @@ function updateArrayDisplay() {
       element.classList.add('swap');
     } else if (animationSteps[currentStep] && animationSteps[currentStep].sorted && animationSteps[currentStep].sorted.includes(index)) {
       element.classList.add('done');
+    } else if (animationSteps[currentStep] && animationSteps[currentStep].activeHeap && index < animationSteps[currentStep].heapSize) {
+      element.classList.add('active-heap');
     }
     
     element.textContent = value;
@@ -184,8 +183,7 @@ function drawHeapTree() {
       }
     }
   }
-  
-  // !! subject to change !!
+
   for (let i = 0; i < Math.min(array.length, positions.length); i++) {
     if (i < heapSize) {
       // determine node color based on current operation
@@ -204,6 +202,10 @@ function drawHeapTree() {
                  animationSteps[currentStep].sorted.includes(i)) {
         nodeColor = '#81ecec';
         borderColor = '#00cec9';
+      } else if (animationSteps[currentStep] && animationSteps[currentStep].activeHeap && i < animationSteps[currentStep].heapSize) {
+        // highlight active heap nodes
+        nodeColor = '#a3d8f4';
+        borderColor = '#0984e3';
       }
       
       // draw rectangle with round corners
@@ -244,18 +246,21 @@ function drawHeapTree() {
 
 function generateAnimationSteps() {
   animationSteps = [];
-  let tempArray = [...array];
+  const originalArray = [5, 3, 8, 1, 9, 4];
+  
+  let tempArray = [...originalArray];
   const n = tempArray.length;
+  
   animationSteps.push({
-    array: [...tempArray],
+    array: [...originalArray],
     line: 0,
-    description: 'Starting heap sort with array [' + tempArray.join(', ') + ']',
+    description: 'Starting heap sort with array [' + originalArray.join(', ') + ']',
     heapSize: n
   });
   
   // build max-heap
   animationSteps.push({
-    array: [...tempArray],
+    array: [...originalArray],
     line: 2,
     description: 'Building max heap',
     heapSize: n
@@ -265,26 +270,36 @@ function generateAnimationSteps() {
   
   for (let i = Math.floor(n / 2) - 1; i >= 0; i--) {
     animationSteps.push({
-      array: [...tempArray],
+      array: [...originalArray],
       line: 3,
       description: `Heapifying subtree rooted at index ${i}`,
       heapSize: n,
       comparing: [i]
     });
     
-    heapifyWithAnimation(tempArray, n, i, sortedIndices);
+    heapifyWithAnimation(tempArray, n, i, sortedIndices, originalArray);
   }
   
   animationSteps.push({
-    array: [...tempArray],
+    array: [...originalArray],
     line: 6,
     description: 'Max heap built. Extracting elements one by one',
     heapSize: n
   });
   
   for (let i = n - 1; i > 0; i--) {
+    // highlight the active heap portion before swap
     animationSteps.push({
-      array: [...tempArray],
+      array: [...originalArray],
+      line: 7,
+      description: `Current active heap size: ${i+1}. Elements from index 0 to ${i} need to be processed.`,
+      heapSize: i + 1,
+      activeHeap: true,
+      sorted: [...sortedIndices]
+    });
+    
+    animationSteps.push({
+      array: [...originalArray],
       line: 8,
       description: `Swapping root (${tempArray[0]}) with element at index ${i} (${tempArray[i]})`,
       heapSize: i + 1,
@@ -297,7 +312,7 @@ function generateAnimationSteps() {
     sortedIndices.push(i);
     
     animationSteps.push({
-      array: [...tempArray],
+      array: [...originalArray],
       line: 8,
       description: `Element ${tempArray[i]} is now in its correct position`,
       heapSize: i,
@@ -305,18 +320,20 @@ function generateAnimationSteps() {
     });
   
     animationSteps.push({
-      array: [...tempArray],
+      array: [...originalArray],
       line: 11,
       description: `Heapifying reduced heap (size ${i})`,
-      heapSize: i
+      heapSize: i,
+      activeHeap: true,
+      sorted: [...sortedIndices]
     });
     
-    heapifyWithAnimation(tempArray, i, 0, sortedIndices);
+    heapifyWithAnimation(tempArray, i, 0, sortedIndices, originalArray);
   }
   
   sortedIndices.push(0);
   animationSteps.push({
-    array: [...tempArray],
+    array: [...originalArray],
     line: 13,
     description: 'Heap sort complete! Array is now sorted: [' + tempArray.join(', ') + ']',
     heapSize: n,
@@ -325,13 +342,13 @@ function generateAnimationSteps() {
 }
 
 // heapify function that records animation steps
-function heapifyWithAnimation(arr, n, i, sortedIndices) {
+function heapifyWithAnimation(arr, n, i, sortedIndices, originalArray) {
   let largest = i;
   const left = 2 * i + 1;
   const right = 2 * i + 2;
   
   animationSteps.push({
-    array: [...arr],
+    array: [...originalArray],
     line: 16,
     description: `Heapifying at index ${i}`,
     heapSize: n,
@@ -342,7 +359,7 @@ function heapifyWithAnimation(arr, n, i, sortedIndices) {
   // compare with left child
   if (left < n) {
     animationSteps.push({
-      array: [...arr],
+      array: [...originalArray],
       line: 21,
       description: `Comparing ${arr[i]} (index ${i}) with left child ${arr[left]} (index ${left})`,
       heapSize: n,
@@ -354,20 +371,39 @@ function heapifyWithAnimation(arr, n, i, sortedIndices) {
       largest = left;
       
       animationSteps.push({
-        array: [...arr],
+        array: [...originalArray],
         line: 22,
         description: `Left child ${arr[left]} is larger than current largest ${arr[i]}`,
         heapSize: n,
         comparing: [largest],
         sorted: sortedIndices ? [...sortedIndices] : []
       });
+    } else {
+      animationSteps.push({
+        array: [...originalArray],
+        line: 21,
+        description: `No action needed: ${arr[i]} (index ${i}) is already larger than or equal to its left child ${arr[left]} (index ${left})`,
+        heapSize: n,
+        comparing: [i],
+        sorted: sortedIndices ? [...sortedIndices] : []
+      });
     }
+  } else {
+    // no left child
+    animationSteps.push({
+      array: [...originalArray],
+      line: 21,
+      description: `No left child exists for node at index ${i}`,
+      heapSize: n,
+      comparing: [i],
+      sorted: sortedIndices ? [...sortedIndices] : []
+    });
   }
   
   // compare with right child
   if (right < n) {
     animationSteps.push({
-      array: [...arr],
+      array: [...originalArray],
       line: 25,
       description: `Comparing ${arr[largest]} (index ${largest}) with right child ${arr[right]} (index ${right})`,
       heapSize: n,
@@ -379,20 +415,39 @@ function heapifyWithAnimation(arr, n, i, sortedIndices) {
       largest = right;
       
       animationSteps.push({
-        array: [...arr],
+        array: [...originalArray],
         line: 26,
         description: `Right child ${arr[right]} is larger than current largest ${arr[largest === i ? arr[i] : arr[left]]}`,
         heapSize: n,
         comparing: [largest],
         sorted: sortedIndices ? [...sortedIndices] : []
       });
+    } else {
+      animationSteps.push({
+        array: [...originalArray],
+        line: 25,
+        description: `No action needed: ${arr[largest]} (index ${largest}) is already larger than or equal to its right child ${arr[right]} (index ${right})`,
+        heapSize: n,
+        comparing: [largest],
+        sorted: sortedIndices ? [...sortedIndices] : []
+      });
     }
+  } else {
+    // there is no right child
+    animationSteps.push({
+      array: [...originalArray],
+      line: 25,
+      description: `No right child exists for node at index ${i}`,
+      heapSize: n,
+      comparing: [i],
+      sorted: sortedIndices ? [...sortedIndices] : []
+    });
   }
   
   // if largest is not root, swap and heapify
   if (largest !== i) {
     animationSteps.push({
-      array: [...arr],
+      array: [...originalArray],
       line: 30,
       description: `Swapping ${arr[i]} (index ${i}) with ${arr[largest]} (index ${largest})`,
       heapSize: n,
@@ -403,7 +458,7 @@ function heapifyWithAnimation(arr, n, i, sortedIndices) {
     [arr[i], arr[largest]] = [arr[largest], arr[i]];
     
     animationSteps.push({
-      array: [...arr],
+      array: [...originalArray],
       line: 33,
       description: `Recursively heapifying the affected subtree rooted at index ${largest}`,
       heapSize: n,
@@ -411,7 +466,17 @@ function heapifyWithAnimation(arr, n, i, sortedIndices) {
       sorted: sortedIndices ? [...sortedIndices] : []
     });
     
-    heapifyWithAnimation(arr, n, largest, sortedIndices);
+    heapifyWithAnimation(arr, n, largest, sortedIndices, originalArray);
+  } else {
+    // add explanation when no swap is needed
+    animationSteps.push({
+      array: [...originalArray],
+      line: 30,
+      description: `No swap needed: Element at index ${i} (${arr[i]}) is already in correct position for max heap`,
+      heapSize: n,
+      comparing: [i],
+      sorted: sortedIndices ? [...sortedIndices] : []
+    });
   }
 }
 
@@ -419,7 +484,7 @@ function nextStep() {
   if (currentStep < animationSteps.length - 1) {
     currentStep++;
     
-    // update the array to current state
+    // always use the original array for display
     if (animationSteps[currentStep] && animationSteps[currentStep].array) {
       array = [...animationSteps[currentStep].array];
     }