Resolve issue with left-hand side panel (#5762)

* enforce light mode for doxygen docs: removed dark theme elements

* fix TOC

Author: brtnfld

doxygen/hdf5doxy.css

@@ -1,26 +1,72 @@
 /**** Table of content in the side-nav ****/
 
+/*
+ * Collapse the navigation tree to zero height instead of removing it from the layout.
+ * This allows the Doxygen scripts to correctly calculate the side-panel's width
+ * and apply the proper 'margin-left' to the main content, preventing overlap.
+ */
+#nav-tree {
+    height: 0;
+    overflow: hidden;
+    padding: 0;
+    margin: 0;
+    border: none;
+}
+
+/* Make sure the side panel itself allows overflow */
+#side-nav {
+  overflow: visible; /* Don't clip the TOC */
+  width: 245px; /* Set initial width (default is usually around 250px) */
+  min-width: 200px; /* Prevent it from getting too small */
+}
 
+/* Style the TOC to fill the entire side panel with proper scrolling */
 div.toc {
-  margin:0;
-  padding: 0.3em 0 0 0;
-  width:100%;
-  float:none;
-  position:absolute;
-  bottom:0;
-  border-radius:0px;
-  border-style: solid none none none;
-  max-height:50%;
-  overflow-y: scroll;
+  margin: 0;
+  padding: 1em 0 0 0;
+  width: 100%;
+  height: calc(100vh - 2em); /* Fixed height to enable proper scrolling */
+  float: none;
+  position: relative;
+  border-radius: 0px;
+  border-style: none;
+  overflow: auto; /* Both horizontal and vertical scrolling */
+  box-sizing: border-box;
 }
 
 div.toc h3 {
   margin-left: 0.5em;
   margin-bottom: 0.2em;
 }
 
+/* Make sure nested lists also scroll properly */
 div.toc ul {
   margin: 0.2em 0 0.4em 0.5em;
+  width: max-content; /* Allow content to determine width */
+  min-width: 100%;
+}
+
+/* Ensure the TOC root container can expand */
+div.toc > ul {
+  width: max-content;
+  min-width: 100%;
+}
+
+/* Ensure TOC entries don't wrap and enable horizontal scrolling */
+div.toc li a {
+    white-space: nowrap;
+    display: inline-block; /* Changed from block to inline-block */
+    width: auto; /* Let content determine width */
+    min-width: 100%; /* Ensure it takes at least full container width */
+}
+
+/*
+ * Prevent long TOC entries from wrapping.
+ * This keeps each entry on a single line and makes the panel
+ * horizontally scrollable if an entry is too wide.
+ */
+#side-nav div.toc li a {
+    white-space: nowrap;
 }
 
 span.cpp11,span.cpp14,span.cpp17 {
@@ -78,9 +124,9 @@ a[href^="https://"]::after
   width: 11px;
   height: 11px;
   margin-left: 4px;
-  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='currentColor' viewBox='0 0 16 16'%3E%3Cpath fill-rule='evenodd' d='M8.636 3.5a.5.5 0 0 0-.5-.5H1.5A1.5 1.5 0 0 0 0 4.5v10A1.5 1.5 0 0 0 1.5 16h10a1.5 1.5 0 0 0 1.5-1.5V7.864a.5.5 0 0 0-1 0V14.5a.5.5 0 0 1-.5.5h-10a.5.5 0 0 1-.5-.5v-10a.5.5 0 0 1 .5-.5h6.636a.5.5 0 0 0 .5-.5z'/%3E%3Cpath fill-rule='evenodd' d='M16 .5a.5.5 0 0 0-.5-.5h-5a.5.5 0 0 0 0 1h3.793L6.146 9.146a.5.5 0 1 0 .708.708L15 1.707V5.5a.5.5 0 0 0 1 0v-5z'/%3E%3C/svg%3E");
+  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='currentColor' viewBox='0 0 16 16'%3E%3Cpath fill-rule='evenodd' d='M8.636 3.5a.5.5 0 0 0-.5-.5H1.5A1.5 1.5 0 0 0 0 4.5v10A1.5 1.5 0 0 0 1.5 16h10a1.5 1.5 0 0 0 1.5-1.5V7.864a.5.5 0 0 0-1 0V14.5a.5.5 0 0 1-.5-.5h-10a.5.5 0 0 1-.5-.5v-10a.5.5 0 0 1 .5-.5h6.636a.5.5 0 0 0 .5-.5z'/%3E%3Cpath fill-rule='evenodd' d='M16 .5a.5.5 0 0 0-.5-.5h-5a.5.5 0 0 0 0 1h3.793L6.146 9.146a.5.5 0 1 0 .708.708L15 1.707V5.5a.5.5 0 0 0 1 0v-5z'/%3E%3C/svg%3E");
   background-position: center;
   background-repeat: no-repeat;
   background-size: contain;
   display: inline-block;
-}
+}