Make presence markers visible.

lynxkite-app/web/src/index.css

@@ -534,3 +534,25 @@ body {
 .add-relationship-button:hover {
   background-color: #218838;
 }
+
+.yRemoteSelection {
+  background-color: rgb(250, 129, 0, 0.5);
+}
+
+.yRemoteSelectionHead {
+  position: absolute;
+  border-left: #ff8800 solid 2px;
+  border-top: #ff8800 solid 2px;
+  border-bottom: #ff8800 solid 2px;
+  height: 100%;
+  box-sizing: border-box;
+}
+
+.yRemoteSelectionHead::after {
+  position: absolute;
+  content: " ";
+  border: 3px solid #ff8800;
+  border-radius: 4px;
+  left: -4px;
+  top: -5px;
+}