Better arrow with <details> / <summary> tags

When having a `<details>` / `<summary>` tags combination the "closed" arrow des not look good (Window / Firefox, Chrome, Edge).
Using the "open" arrow and rotating this

Author: albert-github

templates/html/doxygen.css

@@ -2116,14 +2116,17 @@ details > summary::-webkit-details-marker {
 }
 
 details>summary::before {
-	content: "\25ba";
-	padding-right:4px;
-	font-size: 80%;
+        content: "\25bc";
+        padding-right:4px;
+        font-size: 80%;
+        display: inline-block;
+        transform: rotate(-90deg);
 }
 
 details[open]>summary::before {
-	content: "\25bc";
-	padding-right:4px;
-	font-size: 80%;
+        content: "\25bc";
+        padding-right:4px;
+        font-size: 80%;
+        display: inline-block;
+        transform: rotate(0deg);
 }
-