Add CSS animations and minimal auto-focus JS with graceful fallback

- CSS grid animation for smooth expand/collapse transitions
- Fade-in animation for namespace dropdown
- Auto-focus textarea on details open (progressive enhancement)
- Falls back gracefully if browser lacks support

remarkbox/static/css/common.css

@@ -411,7 +411,7 @@ form.node-action {
   opacity: 0.8 !important;
 }
 
-/* Pure CSS toggle using <details> element */
+/* Pure CSS toggle using <details> element with animations */
 .toggle-summary {
   cursor: pointer;
   list-style: none;
@@ -453,6 +453,33 @@ details[open] > .toggle-summary .when-closed {
   display: none;
 }
 
+/* Animated details content using CSS grid technique */
+.edit-box-details,
+.remark-box-details,
+.node-children-details {
+  --details-transition-duration: 0.3s;
+}
+
+.edit-box-details > .details-content,
+.remark-box-details > .details-content,
+.node-children-details > .details-content {
+  display: grid;
+  grid-template-rows: 0fr;
+  transition: grid-template-rows var(--details-transition-duration) ease-out;
+}
+
+.edit-box-details[open] > .details-content,
+.remark-box-details[open] > .details-content,
+.node-children-details[open] > .details-content {
+  grid-template-rows: 1fr;
+}
+
+.edit-box-details > .details-content > .details-content-inner,
+.remark-box-details > .details-content > .details-content-inner,
+.node-children-details > .details-content > .details-content-inner {
+  overflow: hidden;
+}
+
 /* Edit box details styling */
 .edit-box-details {
   margin-top: 15px;
@@ -480,6 +507,13 @@ details[open] > .toggle-summary .when-closed {
   padding: 10px;
   border: 1px solid #ddd;
   min-width: 120px;
+  /* Fade in animation for dropdown */
+  animation: fadeIn 0.2s ease-out;
+}
+
+@keyframes fadeIn {
+  from { opacity: 0; transform: translateY(-5px); }
+  to { opacity: 1; transform: translateY(0); }
 }
 
 /* Node children collapse/expand */

remarkbox/static/js/custom.js

@@ -38,6 +38,22 @@ function sendPreview(textarea, div, mathjax=false){
 }
 
 
+// Auto-focus textarea when details element opens (progressive enhancement).
+// Falls back gracefully if browser doesn't support the required APIs.
+if (typeof document.addEventListener === 'function') {
+  document.addEventListener('toggle', function(e) {
+    var details = e.target;
+    if (details.tagName !== 'DETAILS' || !details.open) return;
+
+    // Find textarea inside the details element and focus it.
+    var textarea = details.querySelector('textarea');
+    if (textarea && typeof textarea.focus === 'function') {
+      // Small delay to let the CSS transition start.
+      setTimeout(function() { textarea.focus(); }, 50);
+    }
+  }, true);
+}
+
 $(document).ready( function() {
 
   $('button.vote-up').click(

remarkbox/templates/list-nodes.j2

@@ -48,12 +48,16 @@ page: {{ request.page_number }}
 
 <details id="edit-box-{{ node.id }}" class="edit-box-details">
    <summary class="action toggle-summary"><span class="when-closed">edit</span><span class="when-open">hide</span></summary>
+   <div class="details-content"><div class="details-content-inner">
    {{ forms.edit(node) }}
+   </div></div>
 </details>
 
 <details id="remark-box-{{ node.id }}" class="remark-box-details">
    <summary class="remark toggle-summary"><span class="when-closed">remark</span><span class="when-open">hide</span></summary>
+   <div class="details-content"><div class="details-content-inner">
    {{ forms.reply(node, node) }}
+   </div></div>
 </details>
 
 {% endfor -%}

remarkbox/templates/show-node.j2

@@ -77,12 +77,16 @@
 
 <details id="edit-box-{{ request.node.id }}" class="edit-box-details">
    <summary class="action toggle-summary"><span class="when-closed">edit</span><span class="when-open">hide</span></summary>
+   <div class="details-content"><div class="details-content-inner">
    {{ forms.edit(request.node) }}
+   </div></div>
 </details>
 
 <details id="remark-box-{{ request.node.id }}" class="remark-box-details remark-box-details-main" open>
    <summary class="toggle-summary toggle-summary-hidden"></summary>
+   <div class="details-content"><div class="details-content-inner">
    {{ forms.reply(request.node, request.root_node) }}
+   </div></div>
 </details>
 
 
@@ -152,20 +156,26 @@
 
     <details id="edit-box-{{ parent.id }}" class="edit-box-details">
        <summary class="action toggle-summary"><span class="when-closed">edit</span><span class="when-open">hide</span></summary>
+       <div class="details-content"><div class="details-content-inner">
        {{ forms.edit(parent) }}
+       </div></div>
     </details>
 
     <details id="remark-box-{{ parent.id }}" class="remark-box-details">
        <summary class="remark toggle-summary"><span class="when-closed">remark</span><span class="when-open">hide</span></summary>
+       <div class="details-content"><div class="details-content-inner">
        {{ forms.reply(parent, request.root_node) }}
+       </div></div>
     </details>
 
     {#- nest children in this node's div for convo collapsing. -#}
     <details id="node-children-{{ parent.id }}" class="node-children-details" open>
     <summary class="action link toggle-summary"><span class="when-closed">expand [+]</span><span class="when-open">collapse [-]</span></summary>
+    <div class="details-content"><div class="details-content-inner">
     {%- if children_ids %}
     {{ loop(children_ids) }}
     {% endif -%}
+    </div></div>
     </details>
 
     {# close the class="node" div #}