Adding with-3d-shadow style. This style class adds rounded corners and box shadow.

nv.d3.js

@@ -430,7 +430,7 @@ window.nv.tooltip.* also has various helper methods.
             if (container.node() === null) {
                 //Create new tooltip div if it doesn't exist on DOM.
                 container = body.append("div")
-                    .attr("class", "nvtooltip " + (classes? classes: "xy-tooltip"))
+                    .attr("class", "nvtooltip with-3d-shadow " + (classes? classes: "xy-tooltip"))
                     .attr("id",id)
                     ;
             }
@@ -576,7 +576,7 @@ window.nv.tooltip.* also has various helper methods.
       
         //Create new tooltip div if it doesn't exist on DOM.
         var   container = document.createElement('div');
-        container.className = 'nvtooltip ' + (classes ? classes : 'xy-tooltip');
+        container.className = 'nvtooltip with-3d-shadow ' + (classes ? classes : 'xy-tooltip');
 
         var body = parentContainer;
         if ( !parentContainer || parentContainer.tagName.match(/g|svg/i)) {

src/nv.d3.css

@@ -10,6 +10,18 @@
   overflow: hidden;
 }
 
+/********************
+  Box shadow and border radius styling
+*/
+.with-3d-shadow {
+  -moz-box-shadow: 0 5px 10px rgba(0,0,0,.2);
+  -webkit-box-shadow: 0 5px 10px rgba(0,0,0,.2);
+  box-shadow: 0 5px 10px rgba(0,0,0,.2);
+
+  -webkit-border-radius: 6px;
+  -moz-border-radius: 6px;
+  border-radius: 6px;
+}
 
 /********************
  * TOOLTIP CSS
@@ -43,17 +55,9 @@
   -moz-transition: opacity 500ms linear;
   -webkit-transition: opacity 500ms linear;
 
-  transition-delay: 500ms;
-  -moz-transition-delay: 500ms;
-  -webkit-transition-delay: 500ms;
-
-  -moz-box-shadow: 0 5px 10px rgba(0,0,0,.2);
-  -webkit-box-shadow: 0 5px 10px rgba(0,0,0,.2);
-  box-shadow: 0 5px 10px rgba(0,0,0,.2);
-
-  -webkit-border-radius: 6px;
-  -moz-border-radius: 6px;
-  border-radius: 6px;
+  transition-delay: 250ms;
+  -moz-transition-delay: 250ms;
+  -webkit-transition-delay: 250ms;
 }
 
 .nvtooltip.x-nvtooltip,

src/tooltip.js

@@ -116,7 +116,7 @@ window.nv.tooltip.* also has various helper methods.
             if (container.node() === null) {
                 //Create new tooltip div if it doesn't exist on DOM.
                 container = body.append("div")
-                    .attr("class", "nvtooltip " + (classes? classes: "xy-tooltip"))
+                    .attr("class", "nvtooltip with-3d-shadow " + (classes? classes: "xy-tooltip"))
                     .attr("id",id)
                     ;
             }
@@ -262,7 +262,7 @@ window.nv.tooltip.* also has various helper methods.
       
         //Create new tooltip div if it doesn't exist on DOM.
         var   container = document.createElement('div');
-        container.className = 'nvtooltip ' + (classes ? classes : 'xy-tooltip');
+        container.className = 'nvtooltip with-3d-shadow ' + (classes ? classes : 'xy-tooltip');
 
         var body = parentContainer;
         if ( !parentContainer || parentContainer.tagName.match(/g|svg/i)) {