[edit] change arrows color in toc

static/css/main.css

@@ -266,7 +266,6 @@ body {
   margin: auto;
   margin-right: 0;
   font: var(--fa-font-solid);
-  content: "\f054";
   content: "\f0da";
 
 }
@@ -290,7 +289,10 @@ body {
 }
 
 .accordion-button::after {
-  color: var(--main-color);
+  font: var(--fa-font-solid);
+  background-image: none;
+  content: "\f078";
+  width: 1rem;
 }
 
 .accordion-button:focus {
@@ -300,11 +302,13 @@ body {
 .accordion-button:not(.collapsed) {
   color: var(--main-color);
   background-color: var(--test-color);
+  background-image: none;
 }
 
 .accordion-button:not(.collapsed)::after {
-  transform: rotate(-180deg);
-  background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='%23212529'%3e%3cpath fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/%3e%3c/svg%3e")
+  background-image: none;
+  content: "\f078";
+  width: 1rem;
 }
 
 .accordion-body {