Real minus sign instead of hyphen-minus

Minus sign in comparison with hyphen-minus (symbol that prints your keyboard by default) has horizontal line on same level as plus sign and same width, so one can be toggled to another with perfect visuals.
https://en.wikipedia.org/wiki/Plus_and_minus_signs
https://en.wikipedia.org/wiki/Hyphen-minus

assets/css/search.css

@@ -20,7 +20,7 @@ summary:before {
 	width: 40px;
 }
 
-details[open] > summary:before { content: "[ ‒ ]"; }
+details[open] > summary:before { content: "[ − ]"; }
 
 
 #filters-box {