add intra-top routing to minimize retractions when possible

web/kiri/index.css

@@ -1244,6 +1244,17 @@ th, tr, td, label {
     width: 20px;
 }
 
+#top-slider {
+    position: absolute;
+    display: none;
+    top: 60px;
+    left: 50px;
+    right: 50px;
+}
+#anim-slider {
+    width: 100%;
+}
+
 #alert-area {
     display: none;
     justify-content: center;

web/kiri/index.html

@@ -461,6 +461,9 @@
             <div id="alert-text">alerts<br>alerts<br>alerts</div>
         </div>
     </div>
+    <div id="top-slider" class="f-col grow">
+        <input id="anim-slider" type="range" min="0" max="1000" value="0"></input>
+    </div>
 </div>
 </body>
 </html>