diff --git a/caravel/assets/visualizations/heatmap.css b/caravel/assets/visualizations/heatmap.css
index bce1248212303..38d6d6cb2abfe 100644
--- a/caravel/assets/visualizations/heatmap.css
+++ b/caravel/assets/visualizations/heatmap.css
@@ -1,5 +1,13 @@
+.heatmap .slice_container {
+  position: relative;
+  top: 0;
+  left: 0;
+  height: 100%;
+}
+
 .heatmap .axis text {
   font: 10px sans-serif;
+  text-rendering: optimizeLegibility;
 }
 
 .heatmap .axis path,
@@ -30,6 +38,7 @@
   color: #fff;
   border-radius: 2px;
   pointer-events: none;
+  z-index: 1000;
 }
 
 /* Creates a small triangle extender for the tooltip */
diff --git a/caravel/assets/visualizations/heatmap.js b/caravel/assets/visualizations/heatmap.js
index c9100e2c0f917..55ec7ef46efde 100644
--- a/caravel/assets/visualizations/heatmap.js
+++ b/caravel/assets/visualizations/heatmap.js
@@ -11,19 +11,15 @@ require('./heatmap.css');
 // Inspired from http://bl.ocks.org/mbostock/3074470
 // https://jsfiddle.net/cyril123/h0reyumq/
 function heatmapVis(slice) {
-  var margins = {
-    t: 10,
-    r: 10,
-    b: 50,
-    l: 60
-  };
 
   function refresh() {
-    var width = slice.width();
-    var height = slice.height();
-    var hmWidth = width - (margins.l + margins.r);
-    var hmHeight = height - (margins.b + margins.t);
-    var fp = d3.format('.3p');
+    var margin = {
+      top: 10,
+      right: 10,
+      bottom: 35,
+      left: 35
+    };
+
     d3.json(slice.jsonEndpoint(), function (error, payload) {
       var matrix = {};
       if (error) {
@@ -33,6 +29,24 @@ function heatmapVis(slice) {
       var fd = payload.form_data;
       var data = payload.data;
 
+      // Dynamically adjusts  based on max x / y category lengths
+      function adjustMargins(data, margins) {
+        var pixelsPerCharX = 4.5; // approx, depends on font size
+        var pixelsPerCharY = 6.8; // approx, depends on font size
+        var longestX = 1;
+        var longestY = 1;
+        var datum;
+
+        for (var i = 0; i < data.length; i++) {
+          datum = data[i];
+          longestX = Math.max(longestX, datum.x.length || 1);
+          longestY = Math.max(longestY, datum.y.length || 1);
+        }
+
+        margins.left = Math.ceil(Math.max(margins.left, pixelsPerCharY * longestY));
+        margins.bottom = Math.ceil(Math.max(margins.bottom, pixelsPerCharX * longestX));
+      }
+
       function ordScale(k, rangeBands, reverse) {
         if (reverse === undefined) {
           reverse = false;
@@ -53,12 +67,20 @@ function heatmapVis(slice) {
           return d3.scale.ordinal().domain(domain).rangeBands(rangeBands);
         }
       }
+      adjustMargins(data, margin);
+
+      var width = slice.width();
+      var height = slice.height();
+      var hmWidth = width - (margin.left + margin.right);
+      var hmHeight = height - (margin.bottom + margin.top);
+      var fp = d3.format('.3p');
+
       var xScale = ordScale('x');
       var yScale = ordScale('y', undefined, true);
       var xRbScale = ordScale('x', [0, hmWidth]);
       var yRbScale = ordScale('y', [hmHeight, 0]);
       var X = 0,
-        Y = 1;
+          Y = 1;
       var heatmapDim = [xRbScale.domain().length, yRbScale.domain().length];
 
       var color = px.color.colorScalerFactory(fd.linear_color_scheme);
@@ -72,10 +94,7 @@ function heatmapVis(slice) {
         .range([0, hmHeight])
       ];
 
-      var container = d3.select(slice.selector)
-        .style("left", "0px")
-        .style("position", "relative")
-        .style("top", "0px");
+      var container = d3.select(slice.selector);
 
       var canvas = container.append("canvas")
         .attr("width", heatmapDim[X])
@@ -83,8 +102,8 @@ function heatmapVis(slice) {
         .style("width", hmWidth + "px")
         .style("height", hmHeight + "px")
         .style("image-rendering", fd.canvas_image_rendering)
-        .style("left", margins.l + "px")
-        .style("top", margins.t + "px")
+        .style("left", margin.left + "px")
+        .style("top", margin.top + "px")
         .style("position", "absolute");
 
       var svg = container.append("svg")
@@ -95,7 +114,7 @@ function heatmapVis(slice) {
         .style("position", "absolute");
 
       var rect = svg.append('g')
-        .attr("transform", "translate(" + margins.l + "," + margins.t + ")")
+        .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
         .append('rect')
         .style('fill-opacity', 0)
         .attr('stroke', 'black')
@@ -110,18 +129,23 @@ function heatmapVis(slice) {
           return [k[1] - 20, x];
         })
         .html(function (d) {
+          var s = "";
           var k = d3.mouse(this);
           var m = Math.floor(scale[0].invert(k[0]));
           var n = Math.floor(scale[1].invert(k[1]));
           if (m in matrix && n in matrix[m]) {
             var obj = matrix[m][n];
-            var s = "";
             s += "<div><b>" + fd.all_columns_x + ": </b>" + obj.x + "<div>";
             s += "<div><b>" + fd.all_columns_y + ": </b>" + obj.y + "<div>";
             s += "<div><b>" + fd.metric + ": </b>" + obj.v + "<div>";
             s += "<div><b>%: </b>" + fp(obj.perc) + "<div>";
-            return s;
+            tip.style("display", null);
+          } else {
+            // this is a hack to hide the tooltip because we have map it to a single <rect>
+            // d3-tip toggles opacity and calling hide here is undone by the lib after this call
+            tip.style("display", "none");
           }
+          return s;
         });
 
       rect.call(tip);
@@ -133,6 +157,7 @@ function heatmapVis(slice) {
             return !(i % (parseInt(fd.xscale_interval, 10)));
           }))
         .orient("bottom");
+
       var yAxis = d3.svg.axis()
         .scale(yRbScale)
         .tickValues(yRbScale.domain().filter(
@@ -143,16 +168,15 @@ function heatmapVis(slice) {
 
       svg.append("g")
         .attr("class", "x axis")
-        .attr("transform", "translate(" + margins.l + "," + (margins.t + hmHeight) + ")")
+        .attr("transform", "translate(" + margin.left + "," + (margin.top + hmHeight) + ")")
         .call(xAxis)
         .selectAll("text")
         .style("text-anchor", "end")
-        .attr("transform", "rotate(-45)")
-        .style("font-weight", "bold");
+        .attr("transform", "rotate(-45)");
 
       svg.append("g")
         .attr("class", "y axis")
-        .attr("transform", "translate(" + margins.l + ", 0)")
+        .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
         .call(yAxis);
 
       rect.on('mousemove', tip.show);
@@ -196,6 +220,7 @@ function heatmapVis(slice) {
         context.putImageData(image, 0, 0);
         imageObj.src = canvas.node().toDataURL();
       }
+
       slice.done();
 
     });
diff --git a/caravel/forms.py b/caravel/forms.py
index 875395f95bb87..b5ff1db0bfefc 100644
--- a/caravel/forms.py
+++ b/caravel/forms.py
@@ -139,7 +139,7 @@ def __init__(self, viz):
                 'Color Scheme', choices=self.choicify([
                     'fire', 'blue_white_yellow', 'white_black',
                     'black_white']),
-                default='fire',
+                default='blue_white_yellow',
                 description=""),
             'normalize_across': SelectField(
                 'Normalize Across', choices=self.choicify([