diff --git a/unpacked/extensions/MathZoom.js b/unpacked/extensions/MathZoom.js
index a5a75e33b..ac1555536 100644
--- a/unpacked/extensions/MathZoom.js
+++ b/unpacked/extensions/MathZoom.js
@@ -137,24 +137,26 @@
       //
       //  Create the DOM elements for the zoom box
       //
-      var Mw = Math.floor(.85*document.body.clientWidth),
-          Mh = Math.floor(.85*Math.max(document.body.clientHeight,document.documentElement.clientHeight));
+      var container = this.findContainer(math);
+      var Mw = Math.floor(.85*container.clientWidth),
+          Mh = Math.max(document.body.clientHeight,document.documentElement.clientHeight);
+      if (this.getOverflow(container) !== "visible") {Mh = Math.min(container.clientHeight,Mh)}
+      Mh = Math.floor(.85*Mh);
       var div = HTML.Element(
         "span",{id:"MathJax_ZoomFrame"},[
           ["span",{id:"MathJax_ZoomOverlay", onmousedown:this.Remove}],
           ["span",{
             id:"MathJax_Zoom", onclick:this.Remove,
-            style:{
-              visibility:"hidden", fontSize:this.settings.zscale,
-              "max-width":Mw+"px", "max-height":Mh+"px"
-            }
+            style:{visibility:"hidden", fontSize:this.settings.zscale}
           },[["span",{style:{display:"inline-block", "white-space":"nowrap"}}]]
         ]]
       );
       var zoom = div.lastChild, span = zoom.firstChild, overlay = div.firstChild;
       math.parentNode.insertBefore(div,math); math.parentNode.insertBefore(math,div); // put div after math
       if (span.addEventListener) {span.addEventListener("mousedown",this.Remove,true)}
-      
+      var eW = zoom.offsetWidth || zoom.clientWidth; Mw -= eW; Mh -= eW;
+      zoom.style.maxWidth = Mw+"px"; zoom.style.maxHeight = Mh+"px";
+
       if (this.msieTrapEventBug) {
         var trap = HTML.Element("span",{id:"MathJax_ZoomEventTrap", onmousedown:this.Remove});
         div.insertBefore(trap,zoom);
@@ -187,7 +189,7 @@
         if (zoom.offsetWidth  > Mw) {zoom.style.width  = Mw+"px"; zoom.style.height = (bbox.zH+this.scrollSize)+"px"}
       }
       if (this.operaPositionBug) {zoom.style.width = Math.min(Mw,bbox.zW)+"px"}  // Opera gets width as 0?
-      if (zoom.offsetWidth && zoom.offsetWidth < Mw && zoom.offsetHeight < Mh)
+      if (zoom.offsetWidth > eW && zoom.offsetWidth-eW < Mw && zoom.offsetHeight-eW < Mh)
          {zoom.style.overflow = "visible"}  // don't show scroll bars if we don't need to
       this.Position(zoom,bbox);
       if (this.msieTrapEventBug) {
@@ -220,7 +222,9 @@
     //  Set the position of the zoom box and overlay
     //
     Position: function (zoom,bbox) {
+      zoom.style.display = "none"; // avoids getting excessive width in Resize()
       var XY = this.Resize(), x = XY.x, y = XY.y, W = bbox.mW;
+      zoom.style.display = "";
       var dx = -W-Math.floor((zoom.offsetWidth-W)/2), dy = bbox.Y;
       zoom.style.left = Math.max(dx,10-x)+"px"; zoom.style.top = Math.max(dy,10-y)+"px";
       if (!ZOOM.msiePositionBug) {ZOOM.SetWH()} // refigure overlay width/height
@@ -233,13 +237,8 @@
       if (ZOOM.onresize) {ZOOM.onresize(event)}
       var div = document.getElementById("MathJax_ZoomFrame"),
           overlay = document.getElementById("MathJax_ZoomOverlay");
-      var xy = ZOOM.getXY(div);
-      var obj = div.parentNode, overflow = ZOOM.getOverflow(obj);
-      while (obj.parentNode && obj !== document.body && overflow === "visible") {
-        obj = obj.parentNode
-        overflow = ZOOM.getOverflow(obj);
-      }
-      if (overflow !== "visible") {
+      var xy = ZOOM.getXY(div), obj = ZOOM.findContainer(div);
+      if (ZOOM.getOverflow(obj) !== "visible") {
         overlay.scroll_parent = obj;  // Save this for future reference.
         var XY = ZOOM.getXY(obj);     // Remove container position
         xy.x -= XY.x; xy.y -= XY.y;
@@ -252,10 +251,17 @@
     },
     SetWH: function () {
       var overlay = document.getElementById("MathJax_ZoomOverlay");
-      overlay.style.width = overlay.style.height = "1px"; // so scrollWidth/Height will be right below
+      overlay.style.display = "none"; // so scrollWidth/Height will be right below
       var doc = overlay.scroll_parent || document.documentElement || document.body;
       overlay.style.width = doc.scrollWidth + "px";
       overlay.style.height = Math.max(doc.clientHeight,doc.scrollHeight) + "px";
+      overlay.style.display = "";
+    },
+    findContainer: function (obj) {
+      var obj = obj.parentNode;
+      while (obj.parentNode && obj !== document.body && ZOOM.getOverflow(obj) === "visible")
+        {obj = obj.parentNode}
+      return obj;
     },
     //
     //  Look up CSS properties (use getComputeStyle if available, or currentStyle if not)
diff --git a/unpacked/jax/output/HTML-CSS/jax.js b/unpacked/jax/output/HTML-CSS/jax.js
index 6c9af25d2..f24706641 100644
--- a/unpacked/jax/output/HTML-CSS/jax.js
+++ b/unpacked/jax/output/HTML-CSS/jax.js
@@ -772,7 +772,10 @@
       this.outerEm = em / jax.HTMLCSS.scale;
       emex.parentNode.removeChild(emex);
 
+      this.zoomScale = parseInt(HUB.config.menuSettings.zscale) / 100;
       this.idPostfix = "-zoom"; jax.root.toHTML(span,span); this.idPostfix = "";
+      this.zoomScale = 1;
+      
       var width = jax.root.HTMLspanElement().bbox.width;
       if (width) {
         //  Handle full-width displayed equations
@@ -954,7 +957,7 @@
       if (length === MML.SIZE.BIG)    {return 2}
       if (length === MML.SIZE.SMALL)  {return .71}
       if (length === "infinity")      {return HTMLCSS.BIGDIMEN}
-      var factor = this.FONTDATA.TeX_factor;
+      var factor = this.FONTDATA.TeX_factor, emFactor = (HTMLCSS.zoomScale||1) / HTMLCSS.em;
       if (length.match(/mathspace$/)) {return HTMLCSS.MATHSPACE[length]*factor}
       var match = length.match(/^\s*([-+]?(?:\.\d+|\d+(?:\.\d*)?))?(pt|em|ex|mu|px|pc|in|mm|cm|%)?/);
       var m = parseFloat(match[1]||"1"), unit = match[2];
@@ -962,12 +965,12 @@
       if (unit === "em") {return m * factor}
       if (unit === "ex") {return m * HTMLCSS.TeX.x_height * factor}
       if (unit === "%")  {return m / 100 * size}
-      if (unit === "px") {return m / HTMLCSS.em}
-      if (unit === "pt") {return m / 10 * factor}                        // 10 pt to an em
-      if (unit === "pc") {return m * 1.2 * factor}                       // 12 pt to a pc
-      if (unit === "in") {return m * this.pxPerInch / HTMLCSS.em}
-      if (unit === "cm") {return m * this.pxPerInch / HTMLCSS.em / 2.54} // 2.54 cm to an inch
-      if (unit === "mm") {return m * this.pxPerInch / HTMLCSS.em / 25.4} // 10 mm to a cm
+      if (unit === "px") {return m * emFactor}
+      if (unit === "pt") {return m / 10 * factor}                      // 10 pt to an em
+      if (unit === "pc") {return m * 1.2 * factor}                     // 12 pt to a pc
+      if (unit === "in") {return m * this.pxPerInch * emFactor}
+      if (unit === "cm") {return m * this.pxPerInch * emFactor / 2.54} // 2.54 cm to an inch
+      if (unit === "mm") {return m * this.pxPerInch * emFactor / 25.4} // 10 mm to a cm
       if (unit === "mu") {return m / 18 * factor * mu} // 18mu to an em for the scriptlevel
       return m*factor*size;  // relative to given size (or 1em as default)
     },
diff --git a/unpacked/jax/output/SVG/jax.js b/unpacked/jax/output/SVG/jax.js
index e9ca93e6d..7b760b0d1 100644
--- a/unpacked/jax/output/SVG/jax.js
+++ b/unpacked/jax/output/SVG/jax.js
@@ -417,13 +417,21 @@
       emex.parentNode.removeChild(emex);
 
       span.appendChild(this.textSVG);
-      this.mathDIV = span;
+      this.mathDIV = span; this.zoomScale = parseInt(HUB.config.menuSettings.zscale) / 100;
       this.idPostfix = "-zoom"; jax.root.toSVG(span,span); this.idPostfix = "";
+      this.zoomScale = 1;
       span.removeChild(this.textSVG);
       
       if (this.operaZoomRefresh)
         {setTimeout(function () {span.firstChild.style.border="1px solid transparent"},1)}
       //
+      // WebKit bug (issue #749)
+      //  
+      if (span.offsetWidth < span.firstChild.offsetWidth) {
+        span.style.minWidth = span.firstChild.offsetWidth + "px";
+        math.style.minWidth = math.firstChild.offsetWidth + "px";
+      }
+      //
       //  Get height and width of zoomed math and original math
       //
       span.style.position = math.style.position = "absolute";
@@ -465,18 +473,19 @@
       if (length === MML.SIZE.SMALL)  {return  710}
       if (length === "infinity")      {return SVG.BIGDIMEN}
       if (length.match(/mathspace$/)) {return 1000*SVG.MATHSPACE[length]}
+      var emFactor = (this.zoomScale || 1) / SVG.em;
       var match = length.match(/^\s*([-+]?(?:\.\d+|\d+(?:\.\d*)?))?(pt|em|ex|mu|px|pc|in|mm|cm|%)?/);
       var m = parseFloat(match[1]||"1") * 1000, unit = match[2];
       if (size == null) {size = 1000};  if (mu == null) {mu = 1}
       if (unit === "em") {return m}
       if (unit === "ex") {return m * SVG.TeX.x_height/1000}
       if (unit === "%")  {return m / 100 * size / 1000}
-      if (unit === "px") {return m / SVG.em}
-      if (unit === "pt") {return m / 10}                             // 10 pt to an em
-      if (unit === "pc") {return m * 1.2}                            // 12 pt to a pc
-      if (unit === "in") {return m * this.pxPerInch / SVG.em}
-      if (unit === "cm") {return m * this.pxPerInch / SVG.em / 2.54} // 2.54 cm to an inch
-      if (unit === "mm") {return m * this.pxPerInch / SVG.em / 25.4} // 10 mm to a cm
+      if (unit === "px") {return m * emFactor}
+      if (unit === "pt") {return m / 10}                               // 10 pt to an em
+      if (unit === "pc") {return m * 1.2}                              // 12 pt to a pc
+      if (unit === "in") {return m * this.pxPerInch * emFactor}
+      if (unit === "cm") {return m * this.pxPerInch * emFactor / 2.54} // 2.54 cm to an inch
+      if (unit === "mm") {return m * this.pxPerInch * emFactor / 25.4} // 10 mm to a cm
       if (unit === "mu") {return m / 18 * mu}
       return m*size / 1000;  // relative to given size (or 1em as default)
     },