diff --git a/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.css b/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.css
index bd3dbde0..815e98cc 100644
--- a/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.css
+++ b/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.css
@@ -175,7 +175,7 @@ th,td {
 
 .content-collapse {
   overflow: hidden;
-  transition: max-height 0.2s ease-out;
+  /*transition: max-height 0.2s ease-out;*//*removed as it was breaking nested collapsible sections*/
 }
 
 /*Fix for permalinks to collapsible sections*/
diff --git a/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.js b/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.js
index b44f33cf..e428762d 100644
--- a/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.js
+++ b/source/_themes/otc_tcs_sphinx_theme/static/tcs_theme.js
@@ -1,60 +1,76 @@
-var i;
-var contents = document.getElementsByClassName("content-collapse section");
-
-var bashDollarDivs = document.getElementsByClassName("bash-dollars highlight-bash"); 
-
-for (i = 0; i< bashDollarDivs.length; i++) {
-    _pre = bashDollarDivs[i].querySelectorAll("pre");
-    for (j = 0; j < _pre.length; j++) {
-      console.log(_pre[j]);
-      _pre[j].innerHTML="<span class='bash-dollar'>"+(_pre[j].textContent.split("\n").filter(Boolean).join("</span>\n<span class='bash-dollar'>"))+"</span>";
-    }
-}
-
-for (i = 0; i < contents.length; i++) {
-
-  //Make sure the "content-collapse section" class is occurring in <div>
-  if (contents[i].tagName.toLowerCase() == 'div') {
-    var element = contents[i].children[0];
-    var element_type = element.tagName.toLowerCase();
-    var btn_id;
-    var divElement;
-
-    divElement = contents[i];
-    btn_id = contents[i].id;
-
-    //if the next element is a span skip to the header
-    if (element_type == 'span') {
-      element = contents[i].children[1];
-      element_type = element.tagName.toLowerCase();
-    } else {
-      divElement.id = "";
-    }
-
-    var btn = document.createElement("BUTTON");
-    //If it is a header capture which level and pass on to button
-    if (element_type.length == 2 && element_type[0] == 'h') {
-      var newClass = 'clps' + element_type[1];
-      //collapses the section by default only if javascript is working
-      contents[i].style.maxHeight = 0;
-      //Build the button and define behavior
-      btn.className += " " + newClass;
-      btn.innerHTML = element.innerHTML;
-      btn.className += " collapsible";
-      btn.id = btn_id;
-      btn.addEventListener("click", function() {
-        this.classList.toggle("active");
-        var content = this.nextElementSibling;
-        if (content.style.maxHeight != "0px"){
-          content.style.maxHeight = 0;
-        } else {
-          content.style.maxHeight = content.scrollHeight + "px";
-        } 
-      });
-
-      //Add the button to the page and remove the header
-      contents[i].parentNode.insertBefore(btn, contents[i]);
-      contents[i].removeChild(element);
-    }
-  }
-}
\ No newline at end of file
+var i;
+var contents = document.getElementsByClassName("content-collapse section");
+
+var bashDollarDivs = document.getElementsByClassName("bash-dollars highlight-bash"); 
+
+for (i = 0; i< bashDollarDivs.length; i++) {
+    _pre = bashDollarDivs[i].querySelectorAll("pre");
+    for (j = 0; j < _pre.length; j++) {
+      console.log(_pre[j]);
+      _pre[j].innerHTML="<span class='bash-dollar'>"+(_pre[j].textContent.split("\n").filter(Boolean).join("</span>\n<span class='bash-dollar'>"))+"</span>";
+    }
+}
+
+//needed for nested collapsible sections - otherwise the top container 
+//won't resize after expanding a child.
+function resetActiveCollapsedSections() {
+
+  var sections = document.getElementsByClassName("content-collapse section");
+
+  //for (i = 0; i < sections.length; i++) {
+  for (i = sections.length -1; i >= 0; i-- ){
+
+    if (sections[i].style.maxHeight != "0px"){
+       sections[i].style.maxHeight = sections[i].scrollHeight + "px";
+    }
+  }
+}
+
+for (i = 0; i < contents.length; i++) {
+
+  //Make sure the "content-collapse section" class is occurring in <div>
+  if (contents[i].tagName.toLowerCase() == 'div') {
+    var element = contents[i].children[0];
+    var element_type = element.tagName.toLowerCase();
+    var btn_id;
+    var divElement;
+
+    divElement = contents[i];
+    btn_id = contents[i].id;
+
+    //if the next element is a span skip to the header
+    if (element_type == 'span') {
+      element = contents[i].children[1];
+      element_type = element.tagName.toLowerCase();
+    } else {
+      divElement.id = "";
+    }
+
+    var btn = document.createElement("BUTTON");
+    //If it is a header capture which level and pass on to button
+    if (element_type.length == 2 && element_type[0] == 'h') {
+      var newClass = 'clps' + element_type[1];
+      //collapses the section by default only if javascript is working
+      contents[i].style.maxHeight = 0;
+      //Build the button and define behavior
+      btn.className += " " + newClass;
+      btn.innerHTML = element.innerHTML;
+      btn.className += " collapsible";
+      btn.id = btn_id;
+      btn.addEventListener("click", function() {
+        this.classList.toggle("active");
+        var content = this.nextElementSibling;
+        if (content.style.maxHeight != "0px"){
+          content.style.maxHeight = 0;
+        } else {
+          content.style.maxHeight = content.scrollHeight + "px";
+        } 
+        resetActiveCollapsedSections(); //reset the size of parent containers
+      });
+
+      //Add the button to the page and remove the header
+      contents[i].parentNode.insertBefore(btn, contents[i]);
+      contents[i].removeChild(element);
+    }
+  }
+}