diff --git a/src/timeline/Timeline.js b/src/timeline/Timeline.js
index 57ec6a92..7e7786bb 100644
--- a/src/timeline/Timeline.js
+++ b/src/timeline/Timeline.js
@@ -57,17 +57,19 @@ function Timeline (container, items, options) {
   };
 
   // root panel
-  var rootOptions = Object.create(this.options);
-  rootOptions.height = function () {
-    if (me.options.height) {
-      // fixed height
-      return me.options.height;
-    }
-    else {
-      // auto height
-      return (me.timeAxis.height + me.contentPanel.height) + 'px';
+  var rootOptions = util.extend(Object.create(this.options), {
+    height: function () {
+      if (me.options.height) {
+        // fixed height
+        return me.options.height;
+      }
+      else {
+        // auto height
+        // TODO: implement a css based solution to automatically have the right hight
+        return (me.timeAxis.height + me.contentPanel.height) + 'px';
+      }
     }
-  };
+  });
   this.rootPanel = new RootPanel(container, rootOptions);
 
   // single select (or unselect) when tapping an item
@@ -81,10 +83,10 @@ function Timeline (container, items, options) {
 
   // label panel
   var labelOptions = util.extend(Object.create(this.options), {
-    top: '0',
+    top: null,
     bottom: null,
     left: '0',
-    rigth: null,
+    right: null,
     height: '100%',
     width: function () {
       if (me.groupSet) {
@@ -93,21 +95,23 @@ function Timeline (container, items, options) {
       else {
         return 0;
       }
-    }
+    },
+    className: 'labels'
   });
   this.labelPanel = new Panel(labelOptions);
   this.rootPanel.appendChild(this.labelPanel);
 
   // main panel (contains time axis and itemsets)
   var mainOptions = util.extend(Object.create(this.options), {
-    top: '0',
+    top: null,
     bottom: null,
     left: null,
     right: '0',
     height: '100%',
     width: function () {
       return me.rootPanel.width - me.labelPanel.width;
-    }
+    },
+    className: 'main'
   });
   this.mainPanel = new Panel(mainOptions);
   this.rootPanel.appendChild(this.mainPanel);
@@ -153,7 +157,8 @@ function Timeline (container, items, options) {
     left: null,
     right: null,
     height: null,
-    width: null
+    width: null,
+    className: 'content'
   });
   this.contentPanel = new Panel(contentOptions);
   this.mainPanel.appendChild(this.contentPanel);
@@ -323,12 +328,8 @@ Timeline.prototype.setGroups = function(groups) {
 
   // create options for the itemset or groupset
   var options = util.extend(Object.create(this.options), {
-    top: function () {
-      return (me.options.orientation == 'top') ? '0' : '';
-    },
-    bottom: function () {
-      return (me.options.orientation == 'top') ? '' : '0px';
-    },
+    top: null,
+    bottom: null,
     right: null,
     left: null,
     width: null,
diff --git a/src/timeline/component/GroupSet.js b/src/timeline/component/GroupSet.js
index fa504a1e..4387906a 100644
--- a/src/timeline/component/GroupSet.js
+++ b/src/timeline/component/GroupSet.js
@@ -205,7 +205,6 @@ GroupSet.prototype.repaint = function repaint() {
       update = util.updateProperty,
       asSize = util.option.asSize,
       asString = util.option.asString,
-      asElement = util.option.asElement,
       options = this.options,
       orientation = this.getOption('orientation'),
       frame = this.dom.frame,
@@ -239,9 +238,6 @@ GroupSet.prototype.repaint = function repaint() {
     this.dom.labelSet = labelSet;
   }
 
-  // update classname
-  frame.className = 'groupset' + (options.className ? (' ' + asString(options.className)) : '');
-
   var me = this,
       queue = this.queue,
       groups = this.groups,
@@ -291,23 +287,11 @@ GroupSet.prototype.repaint = function repaint() {
       }
     });
 
-    // update the top positions of the groups in the correct order
+    // reorder the groups
     var orderedGroups = this.groupsData.getIds({
       order: this.options.groupOrder
     });
-    for (i = 0; i < orderedGroups.length; i++) {
-      (function (group, prevGroup) {
-        var top = 0;
-        if (prevGroup) {
-          top = function () {
-            return prevGroup.top + prevGroup.height;
-          }
-        }
-        group.setOptions({
-          top: top
-        });
-      })(groups[orderedGroups[i]], groups[orderedGroups[i - 1]]);
-    }
+    // TODO: apply order to the DOM
 
     // (re)create the labels
     while (labelSet.firstChild) {
@@ -361,17 +345,22 @@ GroupSet.prototype.repaint = function repaint() {
     }
   }
 
+  // update classname
+  frame.className = 'groupset' + (options.className ? (' ' + asString(options.className)) : '');
+
   // reposition frame
-  frame.style.height = asSize((options.height != null) ? options.height : height);
-  frame.style.top = asSize(options.top, '0');
-  frame.style.left = asSize(options.left, '0');
-  frame.style.width = asSize(options.width, '100%');
+  frame.style.top     = asSize((orientation == 'top') ? '0' : '');
+  frame.style.bottom  = asSize((orientation == 'top') ? '' : '0');
+  frame.style.left    = asSize(options.left, '');
+  frame.style.right   = asSize(options.right, '');
+  frame.style.width   = asSize(options.width, '100%');
+  frame.style.height  = asSize(height);
 
   // calculate actual size and position
   this.top = frame.offsetTop;
   this.left = frame.offsetLeft;
   this.width = frame.offsetWidth;
-  this.height = frame.offsetHeight;
+  this.height = height;
 
   // reposition labels
   labelSet.style.top = asSize(options.top, '0');
diff --git a/src/timeline/component/ItemSet.js b/src/timeline/component/ItemSet.js
index 7a5cd608..e727b036 100644
--- a/src/timeline/component/ItemSet.js
+++ b/src/timeline/component/ItemSet.js
@@ -175,14 +175,15 @@ ItemSet.prototype.repaint = function repaint() {
   this._updateConversion();
 
   if (!frame) {
-    frame = document.createElement('div');
-    frame['timeline-itemset'] = this;
-    this.frame = frame;
-
     if (!this.parent) throw new Error('Cannot repaint itemset: no parent attached');
     var parentContainer = this.parent.getContainer();
     if (!parentContainer) throw new Error('Cannot repaint itemset: parent has no container element');
 
+    frame = document.createElement('div');
+    frame['timeline-itemset'] = this;
+    parentContainer.appendChild(frame);
+    this.frame = frame;
+
     // create background panel
     var background = document.createElement('div');
     background.className = 'background';
@@ -197,12 +198,9 @@ ItemSet.prototype.repaint = function repaint() {
 
     // create axis panel
     var axis = document.createElement('div');
-    axis.className = 'itemset-axis';
-    //frame.appendChild(axis);
+    axis.className = 'axis';
     this.dom.axis = axis;
-
-    parentContainer.appendChild(frame);
-    parentContainer.appendChild(this.dom.axis);
+    frame.appendChild(axis);
 
     // attach event listeners
     // TODO: use event listeners from the rootpanel to improve performance
@@ -299,45 +297,44 @@ ItemSet.prototype.repaint = function repaint() {
   // recalculate the height of the itemset
   var marginAxis = (options.margin && 'axis' in options.margin) ? options.margin.axis : this.itemOptions.margin.axis,
       marginItem = (options.margin && 'item' in options.margin) ? options.margin.item : this.itemOptions.margin.item,
-      fixedHeight = (asSize(options.height) != null),
       height;
 
-  // height is not specified, determine the height from the height and positioned items
-  if (!fixedHeight) {
-    var visibleItems = this.visibleItems;
-    if (visibleItems.length) {
-      var min = visibleItems[0].top;
-      var max = visibleItems[0].top + visibleItems[0].height;
-      util.forEach(visibleItems, function (item) {
-        min = Math.min(min, item.top);
-        max = Math.max(max, (item.top + item.height));
-      });
-      height = (max - min) + marginAxis + marginItem;
-    }
-    else {
-      height = marginAxis + marginItem;
-    }
+  // determine the height from the stacked items
+  var visibleItems = this.visibleItems;
+  if (visibleItems.length) {
+    var min = visibleItems[0].top;
+    var max = visibleItems[0].top + visibleItems[0].height;
+    util.forEach(visibleItems, function (item) {
+      min = Math.min(min, item.top);
+      max = Math.max(max, (item.top + item.height));
+    });
+    height = (max - min) + marginAxis + marginItem;
+  }
+  else {
+    height = marginAxis + marginItem;
   }
 
   // reposition frame
-  frame.style.left    = asSize(options.left, '0');
-  frame.style.top     = asSize(options.top, '');
-  //frame.style.bottom  = asSize(options.bottom, '');
+  frame.style.left    = asSize(options.left, '');
+  frame.style.right   = asSize(options.right, '');
+  frame.style.top     = asSize((orientation == 'top') ? '0' : '');
+  frame.style.bottom  = asSize((orientation == 'top') ? '' : '0');
   frame.style.width   = asSize(options.width, '100%');
-  frame.style.height  = fixedHeight ? asSize(options.height) : height + 'px';
+  frame.style.height  = asSize(height);
 
   // calculate actual size and position
   this.top = frame.offsetTop;
   this.left = frame.offsetLeft;
   this.width = frame.offsetWidth;
-  this.height = fixedHeight ? frame.offsetHeight : height;
+  this.height = height;
 
   // reposition axis
   this.dom.axis.style.left   = asSize(options.left, '0');
+  this.dom.axis.style.right  = asSize(options.right, '');
   this.dom.axis.style.width  = asSize(options.width, '100%');
-  this.dom.axis.style.top    = (orientation == 'top' ? this.top : this.top + this.height) + 'px';
-  //this.dom.axis.style.top    = asSize(options.top, '');
-  //this.dom.axis.style.bottom = asSize(options.bottom, '');
+  this.dom.axis.style.height = asSize(0);
+  this.dom.axis.style.top    = (orientation == 'top') ? '0' : '';
+  this.dom.axis.style.bottom = (orientation == 'top') ? '' : '0';
 
   return false;
 };
diff --git a/src/timeline/component/Panel.js b/src/timeline/component/Panel.js
index 4ad2c0c0..12f2cf27 100644
--- a/src/timeline/component/Panel.js
+++ b/src/timeline/component/Panel.js
@@ -118,18 +118,13 @@ Panel.prototype._repaintChilds = function () {
  * @private
  */
 Panel.prototype._updateSize = function () {
-  var height = 0;
-  for (var i = 0, ii = this.childs.length; i < ii; i++) {
-    height += this.childs[i].height;
-  }
-
   // apply size
   this.frame.style.top    = util.option.asSize(this.options.top);
   this.frame.style.bottom = util.option.asSize(this.options.bottom);
   this.frame.style.left   = util.option.asSize(this.options.left);
   this.frame.style.right  = util.option.asSize(this.options.right);
   this.frame.style.width  = util.option.asSize(this.options.width, '100%');
-  this.frame.style.height = util.option.asSize(this.options.height, height + 'px');
+  this.frame.style.height = util.option.asSize(this.options.height, '');
 
   // get actual size
   this.top    = this.frame.offsetTop;
diff --git a/src/timeline/component/TimeAxis.js b/src/timeline/component/TimeAxis.js
index 1a84f7d6..89ad28a1 100644
--- a/src/timeline/component/TimeAxis.js
+++ b/src/timeline/component/TimeAxis.js
@@ -73,9 +73,6 @@ TimeAxis.prototype.repaint = function () {
   frame.className = 'axis';
   // TODO: custom className?
 
-  // update its size
-  this.width = frame.offsetWidth; // TODO: only update the width when the frame is resized
-
   if (!frame.parentNode) {
     if (!this.parent) {
       throw new Error('Cannot repaint time axis: no parent attached');
@@ -102,6 +99,8 @@ TimeAxis.prototype.repaint = function () {
     props.minorLabelHeight = showMinorLabels ? props.minorCharHeight : 0;
     props.majorLabelHeight = showMajorLabels ? props.majorCharHeight : 0;
     this.height = props.minorLabelHeight + props.majorLabelHeight;
+    this.width = frame.offsetWidth; // TODO: only update the width when the frame is resized?
+
     props.minorLineHeight = parentHeight + props.minorLabelHeight;
     props.minorLineWidth = 1; // TODO: really calculate width
     props.majorLineHeight = parentHeight + this.height;
diff --git a/src/timeline/component/css/groupset.css b/src/timeline/component/css/groupset.css
index 310e1596..ae37328f 100644
--- a/src/timeline/component/css/groupset.css
+++ b/src/timeline/component/css/groupset.css
@@ -1,6 +1,6 @@
 
 .vis.timeline .groupset {
-  position: absolute;
+  position: relative;
   padding: 0;
   margin: 0;
 }
@@ -21,11 +21,10 @@
 }
 
 .vis.timeline .labels .label-set {
-  position: absolute;
+  position: relative;
   top: 0;
   left: 0;
   width: 100%;
-  height: 100%;
 
   overflow: hidden;
 
@@ -54,13 +53,13 @@
 }
 
 .vis.timeline.top .labels .label-set .vlabel,
-.vis.timeline.top .groupset .itemset-axis {
+.vis.timeline.top .groupset .itemset .axis {
   border-top: 1px solid #bfbfbf;
   border-bottom: none;
 }
 
 .vis.timeline.bottom .labels .label-set .vlabel,
-.vis.timeline.bottom .groupset .itemset-axis {
+.vis.timeline.bottom .groupset .itemset .axis {
   border-top: none;
   border-bottom: 1px solid #bfbfbf;
 }
diff --git a/src/timeline/component/css/itemset.css b/src/timeline/component/css/itemset.css
index c21d8fa1..95b0b678 100644
--- a/src/timeline/component/css/itemset.css
+++ b/src/timeline/component/css/itemset.css
@@ -1,9 +1,11 @@
 
 .vis.timeline .itemset {
-  position: absolute;
+  position: relative;
   padding: 0;
   margin: 0;
-  overflow: hidden;
+
+  -webkit-transition: height .4s ease-in-out;
+  transition:         height .4s ease-in-out;
 }
 
 .vis.timeline .background {
@@ -12,6 +14,6 @@
 .vis.timeline .foreground {
 }
 
-.vis.timeline .itemset-axis {
+.vis.timeline .axis {
   position: absolute;
 }
diff --git a/src/timeline/component/css/panel.css b/src/timeline/component/css/panel.css
index cef917eb..964f6424 100644
--- a/src/timeline/component/css/panel.css
+++ b/src/timeline/component/css/panel.css
@@ -14,7 +14,6 @@
 
 .vis.timeline .vpanel {
   position: absolute;
-  overflow: hidden;
 
   -moz-box-sizing: border-box;
   box-sizing: border-box;