small fixes

app/practice/page.tsx

@@ -117,7 +117,15 @@ export default function PracticePage() {
                   hover
                   className="cursor-pointer"
                   accent={topic.unitColor}
+                  tabIndex={0}
+                  role="button"
                   onClick={() => setSelectedTopic(topic)}
+                  onKeyDown={(e) => {
+                    if (e.key === "Enter" || e.key === " ") {
+                      e.preventDefault();
+                      setSelectedTopic(topic);
+                    }
+                  }}
                 >
                   <div className="flex items-center justify-between">
                     <span className="font-bold">{topic.label}</span>