Update notification when there are no results

src/pages/Index.tsx

@@ -129,11 +129,7 @@ const Index = () => {
     <div className="min-h-screen bg-neutral-light">
       <Header 
         onSearch={setSearchQuery} 
-        showEmptyMessage={
-          (selectedTags.size > 0 || selectedCountries.size > 0) && 
-          filteredConferences.length === 0 && 
-          !showPastConferences
-        }
+        showEmptyMessage={false}
       />
       <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8">
         <div className="space-y-4 py-4">
@@ -144,11 +140,19 @@ const Index = () => {
                 <button
                   key={category.id}
                   className={`px-4 py-2 rounded-md text-sm font-medium transition-colors ${
-                    selectedTags.has(category.id)
-                      ? 'bg-blue-100 text-blue-800'
-                      : 'bg-gray-100 text-gray-700 hover:bg-gray-200'
+                    selectedTags.has(category.id) 
+                      ? 'bg-blue-100 text-blue-800 hover:bg-blue-200' 
+                      : 'bg-neutral-100 text-neutral-700 hover:bg-neutral-200'
                   }`}
-                  onClick={() => toggleTag(category.id)}
+                  onClick={() => {
+                    const newTags = new Set(selectedTags);
+                    if (newTags.has(category.id)) {
+                      newTags.delete(category.id);
+                    } else {
+                      newTags.add(category.id);
+                    }
+                    handleTagsChange(newTags);
+                  }}
                 >
                   {category.label}
                 </button>
@@ -249,6 +253,14 @@ const Index = () => {
         </div>
       </div>
       <main className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
+        {filteredConferences.length === 0 && (
+          <div className="bg-amber-50 border border-amber-200 text-amber-800 rounded-md p-4 mb-6">
+            <p className="text-center">
+              There are no upcoming conferences for the selected categories - enable "Show past conferences" to see previous ones
+            </p>
+          </div>
+        )}
+        
         <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-6">
           {filteredConferences.map((conference: Conference) => (
             <ConferenceCard key={conference.id} {...conference} />