fix some style bugs

diff --git a/dygraph.js b/dygraph.js
index e8afb2b..2c0e202 100644 (file)
--- a/dygraph.js
+++ b/dygraph.js
@@ -2363,7 +2363,19 @@ Dygraph.prototype.annotations = function() {
 Dygraph.addAnnotationRule = function() {
   if (Dygraph.addedAnnotationCSS) return;
 
-  var mysheet=document.styleSheets[0]
+  var mysheet;
+  if (document.styleSheets.length > 0) {
+    mysheet = document.styleSheets[0];
+  } else {
+    var styleSheetElement = document.createElement("style");
+    styleSheetElement.type = "text/css";
+    document.getElementsByTagName("head")[0].appendChild(styleSheetElement);
+    for(i = 0; i < document.styleSheets.length; i++) {
+      if (document.styleSheets[i].disabled) continue;
+      mysheet = document.styleSheets[i];
+    }
+  }
+
   var rule = "border: 1px solid black; " +
              "background-color: white; " +
              "text-align: center;";