fix toc toggle

Author: vitorfloriano

docs/book/theme/css/custom.css

@@ -15,6 +15,15 @@
     justify-content: center; /* horizontal centering */
 }
 
+/* Fixes collapsed headers in TOC */
+.chapter li:not(.expanded) > ol {
+    display: inherit;
+}
+
+.chapter-fold-toggle {
+    display: none;
+}
+
 /* Fixes first header sliding under the menu bar when selected */
 .content {
     overflow-y: clip;