diff --git a/unpacked/jax/output/HTML-CSS/jax.js b/unpacked/jax/output/HTML-CSS/jax.js
index 41a9f39f9..d4e4c33ba 100644
--- a/unpacked/jax/output/HTML-CSS/jax.js
+++ b/unpacked/jax/output/HTML-CSS/jax.js
@@ -1136,14 +1136,20 @@
       if (w > 0 && w*this.em < min) {w = min/this.em}
       if (h+d > 0 && (h+d)*this.em < min) {f = 1/(h+d)*(min/this.em); h *= f; d *= f}
       if (!color) {color = "solid"} else {color = "solid "+color}
-      color = this.Em(w)+" "+color;
-      var H = (f === 1 ? this.Em(h+d) : min+"px"), D = this.Em(-d);
+      var style = {display: "inline-block", overflow:"hidden", verticalAlign:this.Em(-d)};
+      if (w > h+d) {
+        style.borderTop = this.Px(h+d)+" "+color;
+        style.width = this.Em(w);
+        style.height = (this.msieRuleBug && h+d > 0 ? this.Em(h+d) : 0);
+      } else {
+        style.borderLeft = this.Px(w)+" "+color;
+        style.width = (this.msieRuleBug && w > 0 ? this.Em(w) : 0);
+        style.height = this.Em(h+d);
+      }
       var rule = this.addElement(span,"span",{
-        style: {borderLeft: color, display: "inline-block", overflow:"hidden",
-                width:0, height:H, verticalAlign:D},
-        bbox: {h:h, d:d, w:w, rw:w, lw:0, exactW:true}, noAdjust:true, HH:h+d, isMathJax:true
+        style: style, noAdjust:true, HH:h+d, isMathJax:true,
+        bbox: {h:h, d:d, w:w, rw:w, lw:0, exactW:true}
       });
-      if (this.msieRuleBug && w > 0) {rule.style.width = this.Em(w)}
       if (span.isBox || span.className == "mspace") {span.bbox = rule.bbox, span.HH = h+d}
       return rule;
     },