Improve the English translation a bit

index.html

@@ -129,24 +129,20 @@ <h2>Basic modes of the Bullet Chatting</h2>
       </p>
       <ol>
         <li>
-          Rolling Bullet Chatting: Scrolls the screen from the right to the left at a constant speed, showing the
-          top-down priority.
+          Rolling Bullet Chatting: the bullet chat moves from right to left at a constant speed, stacked from top to bottom.
         </li>
         <li>
-          Reverse Barr: Scrolls the screen from the left to the right at a constant speed, showing the top-down
-          priority.
+          Reverse Bullet Chatting: the bullet chat moves from left to right at a constant speed, stacked from top to bottom. This is contrasted against Rolling Bullet Chatting.
         </li>
         <li>
-          Top Bullet Chatting: A Bullet Chatting that is statically centered from top to bottom, with top-down
-          priority.
+          Top Bullet Chatting: A bullet chat that is horizontally and statically centered, stacked from top to bottom.
         </li>
         <li>
-          Bottom Bullet Chatting: A Bullet Chatting that is centered from the bottom up and is displayed with a
-          bottom-up priority.
+          Bottom Bullet Chatting: A bullet chat that is horizontally and statically centered, stacked from bottom to top.
         </li>
       </ol>
         <p>
-          In addition, the Bullet Chatting has higher levels of customization and is out of scope for this document.
+          In addition, Bullet Chatting has higher levels of customization and is out of scope for this document.
         </p>
     </section>