fix: tighten dual-video frame synchronization

Author: MustBeSimo

examples/kern-calibration/README.md

@@ -8,7 +8,7 @@ An original cinematic example website for the `cinematic-scroll` skill.
 - A continuously playing monochrome base video.
 - A synchronized full-colour video above it.
 - Scroll-scrubbed CSS `clip-path` masking applied only to the colour layer.
-- Frame-by-frame drift correction using `requestVideoFrameCallback`, with playback-rate convergence and an 80 ms hard-resync threshold.
+- Frame-by-frame drift correction using `requestVideoFrameCallback`, with playback-rate convergence and a 45 ms hard-resync threshold.
 - Generated precision-mechanical hero imagery converted into a seamless 12-second, 30 fps master loop.
 - Five selectable mechanical systems with live readings and macro crops.
 - Procedural Web Audio ambience behind an explicit user-controlled sound toggle.

examples/kern-calibration/index.html

@@ -98,8 +98,8 @@
   function syncVideos(force=false){
     if(!monoVideo.duration||!colorVideo.duration)return;
     const delta=monoVideo.currentTime-colorVideo.currentTime, drift=Math.abs(delta);
-    if(force||drift>.08){colorVideo.currentTime=monoVideo.currentTime;colorVideo.playbackRate=1;}
-    else colorVideo.playbackRate=1+Math.max(-.06,Math.min(.06,delta*.8));
+    if(force||drift>.045){colorVideo.currentTime=monoVideo.currentTime;colorVideo.playbackRate=1;}
+    else colorVideo.playbackRate=1+Math.max(-.08,Math.min(.08,delta));
     if(monoVideo.paused!==colorVideo.paused){monoVideo.paused?colorVideo.pause():colorVideo.play().catch(()=>{});}
   }
   async function startVideos(){