special tool link background

src/components/site-header/site-search/site-search.scss

@@ -226,6 +226,7 @@
       .list {
         a.search-special-tool {
           align-items: center;
+          background-color: var(--grayscale-white);
           display: flex;
           margin-bottom: 8px;
           text-decoration: none;