Adjust video.

index.html

@@ -109,7 +109,7 @@ <h1 class="title is-1 publication-title">CitDet: A Benchmark Dataset for <br/> C
 <section class="hero is-light is-small">
   <div class="hero-body">
     <div class="container">
-      <div class="item video_1">
+      <div class="item video_1 is-centered">
         <video id="raw" autoplay controls muted loop playsinline width="1024" height="768">
           <source src="./static/videos/video_1.mp4" type="video/mp4">
         </video>