Split arcs and labels to move labels to foreground

Change-Id: Ied6cfe989dfc8f0768d1d5d9e89de75c23031cde
diff --git a/dev/scss/main/tree.scss b/dev/scss/main/tree.scss
index 8ecaf20..3629590 100644
--- a/dev/scss/main/tree.scss
+++ b/dev/scss/main/tree.scss
@@ -33,7 +33,7 @@
   stroke-width: 2px;
 }
 
-g.middle, g.arc {
+g.middle, g.label {
   rect {
     stroke: $darker-orange;
     stroke-width: 2px;
@@ -53,7 +53,6 @@
   }
 }
 
-
 g.leaf.mark text > tspan {
   font-weight: bold;
 }
@@ -72,6 +71,5 @@
   > tspan {
     font-size: 10pt;
     overflow: visible;
-    z-index: 30;
   }
 }