Feat: change searchbtn CSS selector (planning#402)

src/css/style.scss

@@ -112,7 +112,7 @@ img {
 }
 
 @media (min-width: 997px) {
-  .searchBox_node_modules-\@docusaurus-theme-classic-lib-theme-Navbar-Search-styles-module {
+  .navbar__items--right [class^="searchBox"] {
     position: absolute;
     right: 100%;
   }