[filebrowser] Fix regression : dropdown arrows near file with no children

bin/style.css

@@ -5100,7 +5100,10 @@ fancy-tree fancy-scroll fancy-tree-item fancy-button.quieter {
   color: #CCC;
   text-shadow: 1px 1px 1px rgba(0, 0, 0, 0.75);
 }
-fancy-tree fancy-scroll fancy-tree-item fancy-button.quieter.hidden {
+fancy-tree fancy-scroll fancy-tree-item fancy-button.quieter.button-hidden {
+  visibility: hidden;
+}
+fancy-tree fancy-scroll fancy-tree-item .hidden {
   visibility: hidden;
 }
 fancy-tree fancy-scroll fancy-tree-item:hover {

bin/style.less

@@ -6096,13 +6096,17 @@ fancy-tree {
 
 				color: #CCC;
 
-				&.hidden {
+				&.button-hidden {
 					visibility: hidden;
 				}
 
 				text-shadow: 1px 1px 1px rgba(.0,.0,.0,.75);
 			}
 
+			.hidden {
+				visibility: hidden;
+			}
+
 			box-sizing: border-box;
 
 			padding-left: calc((var(--depth) - 1) * 1.0em + 0.25em);

hide/comp/FancyTree.hx

@@ -754,7 +754,7 @@ class FancyTree<TreeItem> extends hide.comp.Component {
 
 		var icon = element.querySelector(".header-icon");
 		var iconContent = getIcon(data.item);
-		icon.classList.toggle("hidden", iconContent == null);
+		icon.classList.toggle("button-hidden", iconContent == null);
 		if (iconContent != null && iconContent != data.iconCache) {
 			icon.innerHTML = iconContent;
 			data.iconCache = iconContent;