Enhance mail subject styling - bold bright white, remove label, add spacing

src/mail/widgets/ContentContainer.py

@@ -121,9 +121,12 @@ class EnvelopeHeader(Vertical):
         self.mount(self.to_label)
         self.mount(self.cc_label)
         self.mount(self.date_label)
+        # Add bottom margin to subject for visual separation from metadata
+        self.subject_label.styles.margin = (0, 0, 1, 0)
 
     def update(self, subject, from_, to, date, cc=None):
-        self.subject_label.update(f"[b]Subject:[/b] {subject}")
+        # Subject is prominent - bold, bright white, no label needed
+        self.subject_label.update(f"[b bright_white]{subject}[/b bright_white]")
         self.from_label.update(f"[b]From:[/b] {from_}")
         self.to_label.update(f"[b]To:[/b] {to}")