match subtitle overlay aspect ratio to video so it stays inside content area

src/pages/PlayerPage.tsx

@@ -970,6 +970,9 @@ export default function PlayerPage() {
 
   /* Track lists from Jellyfin metadata */
   const audioTracks = item ? getAudioStreams(item) : []
+  const videoStream = ((item as any)?.MediaSources?.[0]?.MediaStreams || []).find((s: any) => s.Type === 'Video')
+  const videoWidth = videoStream?.Width || 1920
+  const videoHeight = videoStream?.Height || 1080
 
   /**
    * Pick an audio track. For direct-play sources whose underlying <video>
@@ -1183,6 +1186,8 @@ export default function PlayerPage() {
           <SubtitleOverlay
             playerRef={playerRef}
             subtitleUrl={getSubtitleUrl(serverUrl, id, mediaSourceId, subtitleIndex, token)}
+            videoWidth={videoWidth}
+            videoHeight={videoHeight}
           />
         )
       })()}