diff --git a/core/renderers/common/debugger.js b/core/renderers/common/debugger.js
index f2739d804..3e0da16b2 100644
--- a/core/renderers/common/debugger.js
+++ b/core/renderers/common/debugger.js
@@ -238,7 +238,7 @@ Blockly.blockRendering.Debug.prototype.drawRenderedRow = function(row, cursorY,
       {
         'class': 'elemRenderingRect blockRenderDebug',
         'x': isRtl ? -(row.xPos + row.width) : row.xPos,
-        'y': cursorY,
+        'y': row.yPos,
         'width': row.width,
         'height': row.height,
         'stroke': 'red',
@@ -256,7 +256,7 @@ Blockly.blockRendering.Debug.prototype.drawRenderedRow = function(row, cursorY,
         {
           'class': 'connectedBlockWidth blockRenderDebug',
           'x': isRtl ? -(row.xPos + row.widthWithConnectedBlocks) : row.xPos,
-          'y': cursorY,
+          'y': row.yPos,
           'width': row.widthWithConnectedBlocks,
           'height': row.height,
           'stroke': this.randomColour_,
diff --git a/core/renderers/common/drawer.js b/core/renderers/common/drawer.js
index 2cb9021d0..76e6fa461 100644
--- a/core/renderers/common/drawer.js
+++ b/core/renderers/common/drawer.js
@@ -239,7 +239,7 @@ Blockly.blockRendering.Drawer.prototype.drawBottom_ = function() {
   this.positionNextConnection_();
 
   this.outlinePath_ +=
-    Blockly.utils.svgPaths.lineOnAxis('v', bottomRow.height - bottomRow.overhangY);
+    Blockly.utils.svgPaths.lineOnAxis('V', bottomRow.baseline);
 
   for (var i = elems.length - 1, elem; (elem = elems[i]); i--) {
     if (Blockly.blockRendering.Types.isNextConnection(elem)) {
diff --git a/core/renderers/common/info.js b/core/renderers/common/info.js
index a7649a1a1..c153b6089 100644
--- a/core/renderers/common/info.js
+++ b/core/renderers/common/info.js
@@ -492,20 +492,19 @@ Blockly.blockRendering.RenderInfo.prototype.getSpacerRowHeight_ = function(
 
 /**
  * Calculate the centerline of an element in a rendered row.
+ * This base implementation puts the centerline at the middle of the row
+ * vertically, with no special cases.  You will likely need extra logic to
+ * handle (at minimum) top and bottom rows.
  * @param {!Blockly.blockRendering.Row} row The row containing the element.
- * @param {!Blockly.blockRendering.Measurable} elem The element to place.
+ * @param {!Blockly.blockRendering.Measurable} _elem The element to place.
  * @return {number} The desired centerline of the given element, as an offset
  *     from the top left of the block.
  * @protected
  */
 Blockly.blockRendering.RenderInfo.prototype.getElemCenterline_ = function(row,
-    elem) {
+    _elem) {
   var result = row.yPos;
-  if (Blockly.blockRendering.Types.isNextConnection(elem)) {
-    result += (row.height - row.overhangY + elem.height / 2);
-  } else {
-    result += (row.height / 2);
-  }
+  result += (row.height / 2);
   return result;
 };
 
@@ -538,5 +537,6 @@ Blockly.blockRendering.RenderInfo.prototype.finalize_ = function() {
   this.widthWithChildren = widestRowWithConnectedBlocks + this.startX;
 
   this.height = yCursor;
-  this.startY = this.topRow.startY;
+  this.startY = this.topRow.capline;
+  this.bottomRow.baseline = yCursor - this.bottomRow.descenderHeight;
 };
diff --git a/core/renderers/geras/highlighter.js b/core/renderers/geras/highlighter.js
index a60c019d5..9f5c50799 100644
--- a/core/renderers/geras/highlighter.js
+++ b/core/renderers/geras/highlighter.js
@@ -172,21 +172,21 @@ Blockly.geras.Highlighter.prototype.drawRightSideRow = function(row) {
 };
 
 Blockly.geras.Highlighter.prototype.drawBottomRow = function(row) {
-  var height = row.yPos + row.height - row.overhangY;
+  var baseline = row.baseline;
 
   // Highlight the vertical edge of the bottom row on the input side.
   // Highlighting is always from the top left, both in LTR and RTL.
   if (this.RTL_) {
-    this.steps_.push('V', height - this.highlightOffset_);
+    this.steps_.push('V', baseline - this.highlightOffset_);
   } else {
     var cornerElem = this.info_.bottomRow.elements[0];
     if (Blockly.blockRendering.Types.isLeftSquareCorner(cornerElem)) {
       this.steps_.push(
           Blockly.utils.svgPaths.moveTo(
               row.xPos + this.highlightOffset_,
-              height - this.highlightOffset_));
+              baseline - this.highlightOffset_));
     } else if (Blockly.blockRendering.Types.isLeftRoundedCorner(cornerElem)) {
-      this.steps_.push(Blockly.utils.svgPaths.moveTo(row.xPos, height));
+      this.steps_.push(Blockly.utils.svgPaths.moveTo(row.xPos, baseline));
       this.steps_.push(this.outsideCornerPaths_.bottomLeft());
     }
   }
@@ -214,7 +214,7 @@ Blockly.geras.Highlighter.prototype.drawLeft = function() {
     if (Blockly.blockRendering.Types.isLeftRoundedCorner(topRow.elements[0])) {
       this.steps_.push('V', this.outsideCornerPaths_.height);
     } else {
-      this.steps_.push('V', topRow.startY + this.highlightOffset_);
+      this.steps_.push('V', topRow.capline + this.highlightOffset_);
     }
   }
 };
diff --git a/core/renderers/geras/info.js b/core/renderers/geras/info.js
index 53322a32d..7a8cedcfd 100644
--- a/core/renderers/geras/info.js
+++ b/core/renderers/geras/info.js
@@ -296,6 +296,21 @@ Blockly.geras.RenderInfo.prototype.getSpacerRowHeight_ = function(prev, next) {
  * @override
  */
 Blockly.geras.RenderInfo.prototype.getElemCenterline_ = function(row, elem) {
+  if (Blockly.blockRendering.Types.isBottomRow(row)) {
+    var baseline = row.yPos + row.height - row.descenderHeight;
+    if (Blockly.blockRendering.Types.isNextConnection(elem)) {
+      return baseline + elem.height / 2;
+    }
+    return baseline - elem.height / 2;
+  }
+  if (Blockly.blockRendering.Types.isTopRow(row)) {
+    var capline = row.capline;
+    if (Blockly.blockRendering.Types.isHat(elem)) {
+      return capline - elem.height / 2;
+    }
+    return capline + elem.height / 2;
+  }
+
   var result = row.yPos;
   if (Blockly.blockRendering.Types.isField(elem) ||
       Blockly.blockRendering.Types.isIcon(elem)) {
@@ -306,7 +321,7 @@ Blockly.geras.RenderInfo.prototype.getElemCenterline_ = function(row, elem) {
   } else if (Blockly.blockRendering.Types.isInlineInput(elem)) {
     result += elem.height / 2;
   } else if (Blockly.blockRendering.Types.isNextConnection(elem)) {
-    result += (row.height - row.overhangY + elem.height / 2);
+    result += (row.height - row.descenderHeight + elem.height / 2);
   } else {
     result += (row.height / 2);
   }
@@ -330,7 +345,7 @@ Blockly.geras.RenderInfo.prototype.finalize_ = function() {
     widestRowWithConnectedBlocks =
         Math.max(widestRowWithConnectedBlocks, row.widthWithConnectedBlocks);
     // Add padding to the bottom row if block height is less than minimum
-    var heightWithoutHat = yCursor - this.topRow.startY;
+    var heightWithoutHat = yCursor - this.topRow.ascenderHeight;
     if (row == this.bottomRow &&
         heightWithoutHat < this.constants_.MIN_BLOCK_HEIGHT) {
       // But the hat height shouldn't be part of this.
@@ -345,9 +360,10 @@ Blockly.geras.RenderInfo.prototype.finalize_ = function() {
       xCursor += elem.width;
     }
   }
+  this.bottomRow.baseline = yCursor - this.bottomRow.descenderHeight;
 
   this.widthWithChildren = widestRowWithConnectedBlocks + this.startX;
 
   this.height = yCursor;
-  this.startY = this.topRow.startY;
+  this.startY = this.topRow.capline;
 };
diff --git a/core/renderers/measurables/row_elements.js b/core/renderers/measurables/row_elements.js
index 07bf6f944..e236b5a1b 100644
--- a/core/renderers/measurables/row_elements.js
+++ b/core/renderers/measurables/row_elements.js
@@ -82,7 +82,7 @@ Blockly.blockRendering.Hat = function() {
   this.type |= Blockly.blockRendering.Types.HAT;
   this.height = this.constants_.START_HAT.height;
   this.width = this.constants_.START_HAT.width;
-  this.startY = this.height;
+  this.ascenderHeight = this.height;
 
 };
 goog.inherits(Blockly.blockRendering.Hat, Blockly.blockRendering.Measurable);
@@ -101,7 +101,7 @@ Blockly.blockRendering.SquareCorner = function(opt_position) {
       Blockly.blockRendering.Types.LEFT_SQUARE_CORNER :
       Blockly.blockRendering.Types.RIGHT_SQUARE_CORNER) |
           Blockly.blockRendering.Types.CORNER;
-  this.height = this.constants_.NOTCH.height;
+  this.height = this.constants_.NO_PADDING;
   this.width = this.constants_.NO_PADDING;
 
 };
@@ -125,7 +125,7 @@ Blockly.blockRendering.RoundCorner = function(opt_position) {
   this.width = this.constants_.CORNER_RADIUS;
   // The rounded corner extends into the next row by 4 so we only take the
   // height that is aligned with this row.
-  this.height = this.constants_.NOTCH.height;
+  this.height = this.constants_.CORNER_RADIUS / 2;
 
 };
 goog.inherits(Blockly.blockRendering.RoundCorner,
diff --git a/core/renderers/measurables/rows.js b/core/renderers/measurables/rows.js
index 6a3b08d3e..65066f408 100644
--- a/core/renderers/measurables/rows.js
+++ b/core/renderers/measurables/rows.js
@@ -227,7 +227,9 @@ Blockly.blockRendering.TopRow = function() {
    * @package
    * @type {number}
    */
-  this.startY = 0;
+  this.capline = 0;
+
+  this.ascenderHeight = 0;
 
   /**
    * Whether the block has a previous connection.
@@ -263,7 +265,7 @@ Blockly.blockRendering.TopRow.prototype.populate = function(block) {
   if (hasHat) {
     var hat = new Blockly.blockRendering.Hat();
     this.elements.push(hat);
-    this.startY = hat.startY;
+    this.capline = hat.ascenderHeight;
   } else if (hasPrevious) {
     this.hasPreviousConnection = true;
     this.connection = new Blockly.blockRendering.PreviousConnection(
@@ -300,18 +302,23 @@ Blockly.blockRendering.TopRow.prototype.hasLeftSquareCorner = function(block) {
  * @override
  */
 Blockly.blockRendering.TopRow.prototype.measure = function() {
-  this.width = this.minWidth;
-  this.height = this.minHeight;
+  var height = 0;
+  var width = 0;
+  var ascenderHeight = 0;
   for (var e = 0, elem; (elem = this.elements[e]); e++) {
-    this.width += elem.width;
+    width += elem.width;
     if (!(Blockly.blockRendering.Types.isSpacer(elem))) {
       if (Blockly.blockRendering.Types.isHat(elem)) {
-        this.startY = elem.startY;
-        this.height = this.height + elem.height;
+        ascenderHeight = Math.max(ascenderHeight, elem.ascenderHeight);
+      } else {
+        height = Math.max(height, elem.height);
       }
-      this.height = Math.max(this.height, elem.height);
     }
   }
+  this.width = Math.max(this.minWidth, width);
+  this.height = Math.max(this.minHeight, height) + ascenderHeight;
+  this.ascenderHeight = ascenderHeight;
+  this.capline = this.ascenderHeight;
   this.widthWithConnectedBlocks = this.width;
 };
 
@@ -347,7 +354,9 @@ Blockly.blockRendering.BottomRow = function() {
    * @package
    * @type {number}
    */
-  this.overhangY = 0;
+  this.descenderHeight = 0;
+
+  this.baseline = 0;
 };
 goog.inherits(Blockly.blockRendering.BottomRow, Blockly.blockRendering.Row);
 
@@ -368,7 +377,7 @@ Blockly.blockRendering.BottomRow.prototype.populate = function(block) {
   if (followsStatement) {
     this.minHeight = this.constants_.LARGE_PADDING;
   } else {
-    this.minHeight = this.constants_.NOTCH.height;
+    this.minHeight = this.constants_.MEDIUM_PADDING - 1;
   }
 
   var leftSquareCorner = this.hasLeftSquareCorner(block);
@@ -400,18 +409,24 @@ Blockly.blockRendering.BottomRow.prototype.hasLeftSquareCorner = function(
  * @override
  */
 Blockly.blockRendering.BottomRow.prototype.measure = function() {
-  this.width = this.minWidth;
-  this.height = this.minHeight;
+  var height = 0;
+  var width = 0;
+  var descenderHeight = 0;
   for (var e = 0, elem; (elem = this.elements[e]); e++) {
-    this.width += elem.width;
+    width += elem.width;
     if (!(Blockly.blockRendering.Types.isSpacer(elem))) {
+      // Note: this assumes that next connections have *only* descenderHeight,
+      // with no height above the baseline.
       if (Blockly.blockRendering.Types.isNextConnection(elem)) {
-        this.height = this.height + elem.height;
-        this.overhangY = elem.height;
+        descenderHeight = Math.max(descenderHeight, elem.height);
+      } else {
+        height = Math.max(height, elem.height);
       }
-      this.height = Math.max(this.height, elem.height);
     }
   }
+  this.width = Math.max(this.minWidth, width);
+  this.height = Math.max(this.minHeight, height) + descenderHeight;
+  this.descenderHeight = descenderHeight;
   this.widthWithConnectedBlocks = this.width;
 };
 /**
diff --git a/core/renderers/thrasos/info.js b/core/renderers/thrasos/info.js
index 69dacc466..49bbc9b3f 100644
--- a/core/renderers/thrasos/info.js
+++ b/core/renderers/thrasos/info.js
@@ -297,13 +297,28 @@ Blockly.thrasos.RenderInfo.prototype.getSpacerRowHeight_ = function(
  * @override
  */
 Blockly.thrasos.RenderInfo.prototype.getElemCenterline_ = function(row, elem) {
+  if (Blockly.blockRendering.Types.isBottomRow(row)) {
+    var baseline = row.yPos + row.height - row.descenderHeight;
+    if (Blockly.blockRendering.Types.isNextConnection(elem)) {
+      return baseline + elem.height / 2;
+    }
+    return baseline - elem.height / 2;
+  }
+  if (Blockly.blockRendering.Types.isTopRow(row)) {
+    var capline = row.capline;
+    if (Blockly.blockRendering.Types.isHat(elem)) {
+      return capline - elem.height / 2;
+    }
+    return capline + elem.height / 2;
+  }
+
   var result = row.yPos;
   if (Blockly.blockRendering.Types.isField(elem) && row.hasStatement) {
     var offset = this.constants_.TALL_INPUT_FIELD_OFFSET_Y +
         elem.height / 2;
     result += offset;
   } else if (Blockly.blockRendering.Types.isNextConnection(elem)) {
-    result += (row.height - row.overhangY + elem.height / 2);
+    result += (row.height - row.descenderHeight + elem.height / 2);
   } else {
     result += (row.height / 2);
   }
@@ -327,7 +342,7 @@ Blockly.thrasos.RenderInfo.prototype.finalize_ = function() {
     widestRowWithConnectedBlocks =
         Math.max(widestRowWithConnectedBlocks, row.widthWithConnectedBlocks);
     // Add padding to the bottom row if block height is less than minimum
-    var heightWithoutHat = yCursor - this.topRow.startY;
+    var heightWithoutHat = yCursor - this.topRow.ascenderHeight;
     if (row == this.bottomRow &&
         heightWithoutHat < this.constants_.MIN_BLOCK_HEIGHT) {
       // But the hat height shouldn't be part of this.
@@ -343,8 +358,9 @@ Blockly.thrasos.RenderInfo.prototype.finalize_ = function() {
     }
   }
 
+  this.bottomRow.baseline = yCursor - this.bottomRow.descenderHeight;
   this.widthWithChildren = widestRowWithConnectedBlocks + this.startX;
 
   this.height = yCursor;
-  this.startY = this.topRow.startY;
+  this.startY = this.topRow.capline;
 };
diff --git a/core/renderers/zelos/drawer.js b/core/renderers/zelos/drawer.js
index 3684410bc..c4ab78419 100644
--- a/core/renderers/zelos/drawer.js
+++ b/core/renderers/zelos/drawer.js
@@ -91,7 +91,7 @@ Blockly.zelos.Drawer.prototype.drawBottom_ = function() {
 
   this.outlinePath_ +=
     Blockly.utils.svgPaths.lineOnAxis('v',
-        bottomRow.height - bottomRow.overhangY -
+        bottomRow.height - bottomRow.descenderHeight -
         this.constants_.INSIDE_CORNERS.rightHeight);
 
   for (var i = elems.length - 1, elem; (elem = elems[i]); i--) {
diff --git a/core/renderers/zelos/info.js b/core/renderers/zelos/info.js
index fb38791c6..cdae2c1e4 100644
--- a/core/renderers/zelos/info.js
+++ b/core/renderers/zelos/info.js
@@ -283,6 +283,35 @@ Blockly.zelos.RenderInfo.prototype.getSpacerRowHeight_ = function(
   return this.constants_.MEDIUM_PADDING;
 };
 
+/**
+ * @override
+ */
+Blockly.zelos.RenderInfo.prototype.getElemCenterline_ = function(row,
+    elem) {
+  if (Blockly.blockRendering.Types.isBottomRow(row)) {
+    var baseline = row.yPos + row.height - row.descenderHeight;
+    if (Blockly.blockRendering.Types.isNextConnection(elem)) {
+      return baseline + elem.height / 2;
+    }
+    return baseline - elem.height / 2;
+  }
+  if (Blockly.blockRendering.Types.isTopRow(row)) {
+    var capline = row.capline;
+    if (Blockly.blockRendering.Types.isHat(elem)) {
+      return capline - elem.height / 2;
+    }
+    return capline + elem.height / 2;
+  }
+
+  var result = row.yPos;
+  if (Blockly.blockRendering.Types.isNextConnection(elem)) {
+    result += (row.height - row.descenderHeight + elem.height / 2);
+  } else {
+    result += (row.height / 2);
+  }
+  return result;
+};
+
 /**
  * Modify the given row to add the given amount of padding around its fields.
  * The exact location of the padding is based on the alignment property of the