✨ feat: theme the new error message (#227)

public/static/themes/simple.css

@@ -133,7 +133,8 @@ body {
   height: 1.2rem;
 }
 .results .result_disallowed,
-.results .result_filtered {
+.results .result_filtered,
+.results .result_engine_not_selected {
   display: flex;
   justify-content: center;
   align-items: center;
@@ -144,18 +145,21 @@ body {
 }
 
 .results .result_disallowed .user_query,
-.results .result_filtered .user_query {
+.results .result_filtered .user_query,
+.results .result_engine_not_selected .user_query {
   color: var(--background-color);
   font-weight: 300;
 }
 
 .results .result_disallowed img,
-.results .result_filtered img {
+.results .result_filtered img,
+.results .result_engine_not_selected img {
   width: 30rem;
 }
 
 .results .result_disallowed div,
-.results .result_filtered div {
+.results .result_filtered div,
+.results .result_engine_not_selected div {
   display: flex;
   flex-direction: column;
   gap: 1rem;