fix search snake

Author: EmileTrotignon

src/html_support_files/odoc.css

@@ -984,7 +984,7 @@ td.def-doc *:first-child {
   margin-right: 4px;
   border-radius: 50%;
   border: 3px solid #aaa;
-  border-color: var(--search-snake) transparent var(--search-snake) transparent;
+  border-color: var(--blue-dim) transparent var(--blue-dim) transparent;
   animation: search-snake 1.2s linear infinite;
   position: absolute;
   right: 0;