diff --git a/src/client/components/ExportButton.tsx b/src/client/components/ExportButton.tsx
index 6a3f5de..b3a535e 100644
--- a/src/client/components/ExportButton.tsx
+++ b/src/client/components/ExportButton.tsx
@@ -65,7 +65,7 @@ export function ExportButton({
         btn btn-sm flex-shrink-0 gap-1.5 transition-all duration-200
         ${state === "success" ? "text-white shadow-glow-success" : ""}
         ${state === "error" ? "text-white" : ""}
-        ${state === "idle" || state === "exporting" ? "btn-primary" : ""}
+        ${state === "idle" || state === "exporting" ? "btn-secondary" : ""}
       `}
       style={
         state === "success"
diff --git a/src/server/services/html-exporter.ts b/src/server/services/html-exporter.ts
index 89bc85b..77c1177 100644
--- a/src/server/services/html-exporter.ts
+++ b/src/server/services/html-exporter.ts
@@ -170,16 +170,13 @@ function renderMarkdown(text: string): string {
 }
 
 function formatTimestamp(ts: string): string {
-  try {
-    const d = new Date(ts);
-    return d.toLocaleTimeString(undefined, {
-      hour: "2-digit",
-      minute: "2-digit",
-      second: "2-digit",
-    });
-  } catch {
-    return "";
-  }
+  const d = new Date(ts);
+  if (isNaN(d.getTime())) return "";
+  return d.toLocaleTimeString(undefined, {
+    hour: "2-digit",
+    minute: "2-digit",
+    second: "2-digit",
+  });
 }
 
 function getHighlightCss(): string {