diff --git a/gratipay/testing/browser.py b/gratipay/testing/browser.py
index f62dff3e55..fbcab08803 100644
--- a/gratipay/testing/browser.py
+++ b/gratipay/testing/browser.py
@@ -113,27 +113,34 @@ def wait_for(self, selector, timeout=2):
                     return element
         raise NeverShowedUp(selector)
 
-    def wait_for_notification(self, type='notice'):
-        """Wait for a certain ``type`` of notification. Dismiss the
-        notification and return the message.
+    def wait_for_notification(self, type='notice', message=None, timeout=2):
+        """Wait for a certain ``type`` of notification, with a certain message
+        (if specified). Dismiss the notification and return the message.
         """
-        n_selector = '.notifications-fixed .notification-{}'.format(type)
-        m_selector = 'span.btn-close'
-        notification = self.wait_for(n_selector).first
-        message = notification.find_by_css('div').html
-        notification.find_by_css(m_selector).first.click()
-        self.wait_to_disappear(n_selector + ' ' + m_selector)
+        notification_selector = '.notifications-fixed .notification-{}'.format(type)
+        close_button_selector = 'span.btn-close'
+        end_time = time.time() + timeout
+        while time.time() < end_time:
+            notification = self.wait_for(notification_selector, timeout).first
+            candidate = notification.find_by_css('div').html
+            if message is None or message == candidate:
+                message = candidate
+                break
+        notification.find_by_css(close_button_selector).first.click()
+        self.wait_to_disappear('#{} {}'.format(notification['id'], close_button_selector))
         return message
 
-    def wait_for_success(self):
-        """Wait for a success notification. Dismiss it and return the message.
+    def wait_for_success(self, message=None):
+        """Wait for a success notification, with a certain message (if
+        specified). Dismiss it and return the message.
         """
-        return self.wait_for_notification('success')
+        return self.wait_for_notification('success', message)
 
-    def wait_for_error(self):
-        """Wait for an error notification. Dismiss it and return the message.
+    def wait_for_error(self, message=None):
+        """Wait for an error notification, with a certain message (if
+        specified). Dismiss it and return the message.
         """
-        return self.wait_for_notification('error')
+        return self.wait_for_notification('error', message)
 
     def __getattr__(self, name):
         try:
diff --git a/js/gratipay/notification.js b/js/gratipay/notification.js
index cc74e14f0d..09c257e2e6 100644
--- a/js/gratipay/notification.js
+++ b/js/gratipay/notification.js
@@ -5,11 +5,22 @@
 Gratipay.notification = function(text, type, timeout, closeCallback) {
     var type = type || 'notice';
     var timeout = timeout || (type == 'error' ? 10000 : 5000);
+    var id = Math.random().toString(36).substring(2, 100);
 
-    var dialog = ['div', { 'class': 'notification notification-' + type }, [ 'div', text ]];
+    // We want the notification to be fixed at the top of the page even while
+    // scrolling, without interfering with the heading that's already at the
+    // top of the page when scrolled the whole way up (logo, sign in, etc.). So
+    // what we do is create two notification divs. One sits behind and pushes
+    // the rest of the page content down, so that the header remains visible.
+    // The other sits in front, and is the one the user actually interacts
+    // with. It stays at the top of the viewport even while scrolling.
+
+    var placeholder = ['div', {'class': 'notification notification-' + type}, ['div', text]];
+    var dialog = ['div', {'class': 'notification notification-' + type, 'id': 'notification-'+id},
+                                                                                    ['div', text]];
     var $dialog = $([
-        Gratipay.jsonml(dialog),
-        Gratipay.jsonml(dialog)
+        Gratipay.jsonml(placeholder),   // pushes the whole page down, but not directly seen
+        Gratipay.jsonml(dialog)         // parked at the top even while scrolling
     ]);
 
     // Close if we're on the page the notification links to.
diff --git a/requirements.txt b/requirements.txt
index f1ecc4593e..5bbcae0225 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -39,7 +39,7 @@
 ./vendor/Faker-0.7.3.tar.gz
 
 ./vendor/six-1.8.0.tar.gz
-./vendor/libsass-0.3.0.tar.gz
+./vendor/libsass-0.12.3.tar.gz
 ./vendor/honcho-cfcc7ebb.tar.gz
 
 ./vendor/environment-1.0.0.tar.gz
diff --git a/vendor/libsass-0.12.3.tar.gz b/vendor/libsass-0.12.3.tar.gz
new file mode 100644
index 0000000000..8c6d88c836
Binary files /dev/null and b/vendor/libsass-0.12.3.tar.gz differ
diff --git a/vendor/libsass-0.3.0.tar.gz b/vendor/libsass-0.3.0.tar.gz
deleted file mode 100644
index e8601ea77d..0000000000
Binary files a/vendor/libsass-0.3.0.tar.gz and /dev/null differ