diff --git a/packages/ui/src/components/message-item.tsx b/packages/ui/src/components/message-item.tsx
index 92f7fc5b..e68d51fd 100644
--- a/packages/ui/src/components/message-item.tsx
+++ b/packages/ui/src/components/message-item.tsx
@@ -173,7 +173,7 @@ export default function MessageItem(props: MessageItemProps) {
             <span class="font-semibold text-xs text-[var(--message-user-border)]">You</span>
           </Show>
           <Show when={!isUser()}>
-            <span class="font-semibold text-xs text-[var(--message-assistant-border)]">Assistant</span>
+            <span class="text-xs text-[var(--message-assistant-border)]">Assistant</span>
           </Show>
         </div>
         <div class="flex items-center gap-2">
diff --git a/packages/ui/src/components/message-stream-v2.tsx b/packages/ui/src/components/message-stream-v2.tsx
index 4513bf3a..37b6ed6d 100644
--- a/packages/ui/src/components/message-stream-v2.tsx
+++ b/packages/ui/src/components/message-stream-v2.tsx
@@ -917,7 +917,7 @@ function ReasoningCard(props: ReasoningCardProps) {
     <div class="message-item-base assistant-message bg-[var(--message-assistant-bg)] border-l-4 border-[var(--message-assistant-border)]">
       <div class="reasoning-card-header">
         <div class="flex flex-col">
-          <span class="font-semibold text-xs text-[var(--message-assistant-border)]">Thinking</span>
+          <span class="text-xs text-[var(--message-assistant-border)]">Thinking</span>
         </div>
         <div class="reasoning-card-header-right">
           <button type="button" class="reasoning-card-toggle" onClick={toggle} aria-expanded={expanded()} aria-label={expanded() ? "Collapse thinking" : "Expand thinking"}>