--- a/lib/js/urweb.js	Sun May 06 15:46:25 2012 -0400
+++ b/lib/js/urweb.js	Sun May 06 16:08:48 2012 -0400
@@ -1748,6 +1748,46 @@
 }
 
 
+// CSS validation
+
+function atom(s) {
+    for (var i = 0; i < s.length; ++i) {
+        var c = s[i];
+        if (!isAlnum(c) && c != '+' && c != '-' && c != '.' && c != '%' && c != '#')
+            er("Disallowed character in CSS atom");
+    }
+
+    return s;
+}
+
+function css_url(s) {
+    for (var i = 0; i < s.length; ++i) {
+        var c = s[i];
+        if (!isAlnum(c) && c != ':' && c != '/' && c != '.' && c != '_' && c != '+'
+            && c != '-' && c != '%' && c != '?' && c != '&' && c != '=' && c != '#')
+            er("Disallowed character in CSS URL");
+    }
+
+    return s;
+}
+
+function property(s) {
+    if (s.length <= 0)
+        er("Empty CSS property");
+
+    if (!isLower(s[0]) && s[0] != '_')
+        er("Bad initial character in CSS property");
+
+    for (var i = 0; i < s.length; ++i) {
+        var c = s[i];
+        if (!isLower(c) && !isDigit(c) && c != '_' && c != '-')
+            er("Disallowed character in CSS property");
+    }
+
+    return s;
+}
+
+
 // ID generation
 
 var nextId = 0;