[style] Fix listing connection levels.

static/style.css

@@ -195,8 +195,11 @@ img {
 }
 
 .node .node {
-    padding: 1ex 0 1ex 1ex;
+    padding: 1ex 0.25ex 1ex 1ex;
-    border-left: 1px dashed #2c3e50;
+    border-left: 3px solid #5e235e;
+    margin-bottom: 1ex;
+    border-radius: 3px;
+    box-shadow: 0 0 3px 0px rgba(0,0,0,0.3);
 }
 
 .node.collapsed > .contents {
@@ -263,6 +266,11 @@ img {
     border-left: 2px solid var(--tree-color);
 }
 
+.node .contents ul ul ul li,
+.global-table-of-contents ul ul ul li {
+    margin-left: calc(0px + var(--tree-radius) * 2 + .5ex);
+}
+
 .node .contents ul ul li::marker,
 .global-table-of-contents ul ul li::marker {
     content: '';