Fix sprockets compilation error related to filter: progid:

```
Invalid CSS after "...);filter:progid": expected ";", was ": DXImageTransf..."
```

Author: kle-roy

debug/simplemde.css

@@ -427,7 +427,7 @@ span.CodeMirror-selectedtext { background: none; }
 	background: -o-linear-gradient(left, rgba(255, 255, 255, 1) 0%, rgba(125, 185, 232, 0.01) 100%);
 	background: -ms-linear-gradient(left, rgba(255, 255, 255, 1) 0%, rgba(125, 185, 232, 0.01) 100%);
 	background: linear-gradient(to right, rgba(255, 255, 255, 1) 0%, rgba(125, 185, 232, 0.01) 100%);
-	filter: progid: DXImageTransform.Microsoft.gradient( startColorstr='#ffffff', endColorstr='#037db9e8', GradientType=1);
+	filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffffff', endColorstr='#037db9e8', GradientType=1);
 	position: fixed;
 	top: 0;
 	left: 0;
@@ -444,7 +444,7 @@ span.CodeMirror-selectedtext { background: none; }
 	background: -o-linear-gradient(left, rgba(125, 185, 232, 0.01) 0%, rgba(254, 254, 255, 1) 99%, rgba(255, 255, 255, 1) 100%);
 	background: -ms-linear-gradient(left, rgba(125, 185, 232, 0.01) 0%, rgba(254, 254, 255, 1) 99%, rgba(255, 255, 255, 1) 100%);
 	background: linear-gradient(to right, rgba(125, 185, 232, 0.01) 0%, rgba(254, 254, 255, 1) 99%, rgba(255, 255, 255, 1) 100%);
-	filter: progid: DXImageTransform.Microsoft.gradient( startColorstr='#037db9e8', endColorstr='#ffffff', GradientType=1);
+	filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#037db9e8', endColorstr='#ffffff', GradientType=1);
 	position: fixed;
 	top: 0;
 	right: 0;
@@ -643,6 +643,7 @@ span.CodeMirror-selectedtext { background: none; }
 .CodeMirror .CodeMirror-code .cm-strikethrough {
 	text-decoration: line-through;
 }
+
 .CodeMirror .cm-spell-error:not(.cm-url):not(.cm-comment) {
 	 background: rgba(255, 0, 0, .15);
 }