diff --git a/cms/static/cms/js/require-config.js b/cms/static/cms/js/require-config.js
index 05c935425f..1755ac4bb4 100644
--- a/cms/static/cms/js/require-config.js
+++ b/cms/static/cms/js/require-config.js
@@ -95,7 +95,7 @@
             // end of Annotation tool files
 
             // externally hosted files
-            mathjax: '//cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',  // eslint-disable-line max-len
+            mathjax: '//cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',  // eslint-disable-line max-len
             'youtube': [
                 // youtube URL does not end in '.js'. We add '?noext' to the path so
                 // that require.js adds the '.js' to the query component of the URL,
diff --git a/cms/static/cms/js/spec/main.js b/cms/static/cms/js/spec/main.js
index 1490f36faf..26b09c9c3a 100644
--- a/cms/static/cms/js/spec/main.js
+++ b/cms/static/cms/js/spec/main.js
@@ -55,7 +55,7 @@
             'domReady': 'xmodule_js/common_static/js/vendor/domReady',
             'URI': 'xmodule_js/common_static/js/vendor/URI.min',
             'mock-ajax': 'xmodule_js/common_static/js/vendor/mock-ajax',
-            mathjax: '//cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',   // eslint-disable-line max-len
+            mathjax: '//cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',   // eslint-disable-line max-len
             'youtube': '//www.youtube.com/player_api?noext',
             'coffee/src/ajax_prefix': 'xmodule_js/common_static/coffee/src/ajax_prefix',
             'js/spec/test_utils': 'js/spec/test_utils'
diff --git a/cms/static/cms/js/spec/main_squire.js b/cms/static/cms/js/spec/main_squire.js
index b4eb462775..49850e0999 100644
--- a/cms/static/cms/js/spec/main_squire.js
+++ b/cms/static/cms/js/spec/main_squire.js
@@ -48,7 +48,7 @@
             'draggabilly': 'xmodule_js/common_static/js/vendor/draggabilly',
             'domReady': 'xmodule_js/common_static/js/vendor/domReady',
             'URI': 'xmodule_js/common_static/js/vendor/URI.min',
-            mathjax: '//cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',   // eslint-disable-line max-len
+            mathjax: '//cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',   // eslint-disable-line max-len
             'youtube': '//www.youtube.com/player_api?noext',
             'coffee/src/ajax_prefix': 'xmodule_js/common_static/coffee/src/ajax_prefix'
         },
diff --git a/common/lib/xmodule/xmodule/css/capa/display.scss b/common/lib/xmodule/xmodule/css/capa/display.scss
index 2d0fd65ccf..8e24e08b66 100644
--- a/common/lib/xmodule/xmodule/css/capa/display.scss
+++ b/common/lib/xmodule/xmodule/css/capa/display.scss
@@ -975,7 +975,7 @@ div.problem .action {
     }
     .submit {
       @include margin-right($baseline / 2);
-      float: left;
+      @include float(left);
     }
   }
 
diff --git a/common/static/common/js/discussion/mathjax_include.js b/common/static/common/js/discussion/mathjax_include.js
index 942dc54b58..34594f86ca 100644
--- a/common/static/common/js/discussion/mathjax_include.js
+++ b/common/static/common/js/discussion/mathjax_include.js
@@ -42,6 +42,6 @@ if (typeof MathJax === 'undefined') {
             });
         };
     };
-    vendorScript.src = 'https://cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-MML-AM_SVG';
+    vendorScript.src = 'https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?config=TeX-MML-AM_SVG';
     document.body.appendChild(vendorScript);
 }
diff --git a/common/templates/mathjax_include.html b/common/templates/mathjax_include.html
index c41818c3e5..7c8d0c99ca 100644
--- a/common/templates/mathjax_include.html
+++ b/common/templates/mathjax_include.html
@@ -76,4 +76,4 @@
 <!-- This must appear after all mathjax-config blocks, so it is after the imports from the other templates.
      It can't be run through static.url because MathJax uses crazy url introspection to do lazy loading of
      MathJax extension libraries -->
-<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-MML-AM_SVG"></script>
+<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?config=TeX-MML-AM_SVG"></script>
diff --git a/common/test/acceptance/pages/lms/teams.py b/common/test/acceptance/pages/lms/teams.py
index 4a06c5905a..d8722f15c2 100644
--- a/common/test/acceptance/pages/lms/teams.py
+++ b/common/test/acceptance/pages/lms/teams.py
@@ -6,7 +6,7 @@ Teams pages.
 from common.test.acceptance.pages.lms.course_page import CoursePage
 from common.test.acceptance.pages.lms.discussion import InlineDiscussionPage
 from common.test.acceptance.pages.common.paging import PaginatedUIMixin
-from common.test.acceptance.pages.common.utils import confirm_prompt
+from common.test.acceptance.pages.common.utils import confirm_prompt, click_css
 
 from common.test.acceptance.pages.lms.fields import FieldsMixin
 
@@ -502,7 +502,7 @@ class TeamPage(CoursePage, PaginatedUIMixin, BreadcrumbsMixin):
 
     def click_leave_team_link(self, remaining_members=0, cancel=False):
         """ Click on Leave Team link"""
-        self.q(css='.leave-team-link').first.click()
+        click_css(self, '.leave-team-link', require_notification=False)
         confirm_prompt(self, cancel, require_notification=False)
 
         if cancel is False:
diff --git a/common/test/acceptance/tests/lms/test_teams.py b/common/test/acceptance/tests/lms/test_teams.py
index 41e376cd94..6983f72096 100644
--- a/common/test/acceptance/tests/lms/test_teams.py
+++ b/common/test/acceptance/tests/lms/test_teams.py
@@ -1042,8 +1042,21 @@ class CreateTeamTest(TeamFormActions):
         Then I should see the error message and highlighted fields.
         """
         self.verify_and_navigate_to_create_team_page()
-        self.team_management_page.submit_form()
 
+        # `submit_form` clicks on a button, but that button doesn't always
+        # have the click event handler registered on it in time. That's why
+        # this test is flaky. Unfortunately, I don't know of a straightforward
+        # way to write something that waits for that event handler to be bound
+        # to the button element. So I used time.sleep as well, even though
+        # the bok choy docs explicitly ask us not to:
+        # http://bok-choy.readthedocs.io/en/latest/guidelines.html
+        # Sorry! For the story to address this anti-pattern, see TNL-5820
+        time.sleep(0.5)
+        self.team_management_page.submit_form()
+        self.team_management_page.wait_for(
+            lambda: self.team_management_page.validation_message_text,
+            "Validation message text never loaded."
+        )
         self.assertEqual(
             self.team_management_page.validation_message_text,
             'Check the highlighted fields below and try again.'
@@ -1150,6 +1163,13 @@ class CreateTeamTest(TeamFormActions):
         self.assertTrue(self.browse_teams_page.get_pagination_header_text().startswith('Showing 0 out of 0 total'))
 
         self.verify_and_navigate_to_create_team_page()
+
+        # We add a sleep here to allow time for the click event handler to bind
+        # to the cancel button. Using time.sleep in bok-choy tests is,
+        # generally, an anti-pattern. So don't copy this :).
+        # For the story to address this anti-pattern, see TNL-5820
+        time.sleep(0.5)
+
         self.team_management_page.cancel_team()
 
         self.assertTrue(self.browse_teams_page.is_browser_on_page())
@@ -1940,6 +1960,13 @@ class TeamPageTest(TeamsTabBase):
             }
         ]
         with self.assert_events_match_during(event_filter=self.only_team_events, expected_events=expected_events):
+            # I think we're seeing the same problem that we're seeing in
+            # CreateTeamTest.test_user_can_see_error_message_for_missing_data.
+            # We click on the "leave team" link after it's loaded, but before
+            # its JavaScript event handler is added. Adding this sleep gives
+            # enough time for that event handler to bind to the link. Sorry!
+            # For the story to address this anti-pattern, see TNL-5820
+            time.sleep(0.5)
             self.team_page.click_leave_team_link()
         self.assert_team_details(num_members=0, is_member=False)
         self.assertTrue(self.team_page.join_team_button_present)
diff --git a/lms/static/js/instructor_dashboard/membership.js b/lms/static/js/instructor_dashboard/membership.js
index e45bb8998b..94b104ad26 100644
--- a/lms/static/js/instructor_dashboard/membership.js
+++ b/lms/static/js/instructor_dashboard/membership.js
@@ -12,7 +12,11 @@ such that the value can be defined later than this assignment (file load order).
 (function() {
     'use strict';
     var AuthListWidget, BatchEnrollment, BetaTesterBulkAddition,
-        MemberListWidget, Membership, emailStudents, plantTimeout, statusAjaxError;
+        MemberListWidget, Membership, emailStudents, plantTimeout, statusAjaxError,
+        /* eslint-disable */
+        __hasProp = {}.hasOwnProperty,
+        __extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };
+        /* eslint-enable */
 
     plantTimeout = function() {
         return window.InstructorDashboard.util.plantTimeout.apply(this, arguments);
@@ -38,10 +42,8 @@ such that the value can be defined later than this assignment (file load order).
                 add_btn_label: 'Add Member',
                 add_handler: function() {}
             });
-            templateHtml = $('#member-list-widget-template').html();
-            edx.HtmlUtils.setHtml(
-                this.$container, window.Mustache.render(templateHtml, edx.HtmlUtils.HTML(memberListParams))
-            );
+            templateHtml = window.Mustache.render($('#member-list-widget-template').html(), memberListParams);
+            edx.HtmlUtils.setHtml(this.$container, edx.HtmlUtils.HTML(templateHtml));
             this.$('input[type="button"].add').click(function() {
                 condition = typeof memberListParams.add_handler === 'function';
                 return condition ? memberListParams.add_handler(memberlistwidget.$('.add-field').val()) : undefined;
@@ -64,7 +66,7 @@ such that the value can be defined later than this assignment (file load order).
                 item = rowArray[i];
                 $td = $('<td>');
                 if (item instanceof jQuery) {
-                    edx.HtmlUtils.append($td, item);
+                    edx.HtmlUtils.append($td, edx.HtmlUtils.HTML(item));
                 } else {
                     $td.text(item);
                 }
@@ -86,13 +88,14 @@ such that the value can be defined later than this assignment (file load order).
         return memberListWidget;
     }());
 
-    AuthListWidget = (function() {
-        function authListWidget($container, rolename, $errorSection) {
+    AuthListWidget = (function(_super) {
+        __extends(AuthListWidget, _super);  // eslint-disable-line no-use-before-define
+        function AuthListWidget($container, rolename, $errorSection) {  // eslint-disable-line no-shadow
             var msg,
                 authlistwidget = this;
             this.rolename = rolename;
             this.$errorSection = $errorSection;
-            authListWidget.super.constructor.call(this, $container, {
+            AuthListWidget.__super__.constructor.call(this, $container, {  // eslint-disable-line no-underscore-dangle
                 title: $container.data('display-name'),
                 info: $container.data('info-text'),
                 labels: [gettext('Username'), gettext('Email'), gettext('Revoke access')],
@@ -112,13 +115,13 @@ such that the value can be defined later than this assignment (file load order).
             this.reload_list();
         }
 
-        authListWidget.prototype.re_view = function() {
+        AuthListWidget.prototype.re_view = function() {
             this.clear_errors();
             this.clear_input();
             return this.reload_list();
         };
 
-        authListWidget.prototype.add_handler = function(input) {
+        AuthListWidget.prototype.add_handler = function(input) {
             var authlistwidgetaddhandler = this;
             if ((input != null) && input !== '') {
                 return this.modify_member_access(input, 'allow', function(error) {
@@ -134,7 +137,7 @@ such that the value can be defined later than this assignment (file load order).
             }
         };
 
-        authListWidget.prototype.reload_list = function() {
+        AuthListWidget.prototype.reload_list = function() {
             var authlistwidgetreloadlist = this;
             return this.get_member_list(function(error, memberList) {
                 if (error !== null) {
@@ -163,19 +166,19 @@ such that the value can be defined later than this assignment (file load order).
             });
         };
 
-        authListWidget.prototype.clear_errors = function() {
+        AuthListWidget.prototype.clear_errors = function() {
             var ref, result;
             result = (this.$error_section) != null ? ref.text('') : undefined;
             return result;
         };
 
-        authListWidget.prototype.show_errors = function(msg) {
+        AuthListWidget.prototype.show_errors = function(msg) {
             var ref, result;
             result = (this.$error_section) != null ? ref.text(msg) : undefined;
             return result;
         };
 
-        authListWidget.prototype.get_member_list = function(cb) {
+        AuthListWidget.prototype.get_member_list = function(cb) {
             var authlistwidgetgetmemberlist = this;
             return $.ajax({
                 type: 'POST',
@@ -190,7 +193,7 @@ such that the value can be defined later than this assignment (file load order).
             });
         };
 
-        authListWidget.prototype.modify_member_access = function(uniqueStudentIdentifier, action, cb) {
+        AuthListWidget.prototype.modify_member_access = function(uniqueStudentIdentifier, action, cb) {
             var authlistwidgetmemberaccess = this;
             return $.ajax({
                 type: 'POST',
@@ -210,7 +213,7 @@ such that the value can be defined later than this assignment (file load order).
             });
         };
 
-        authListWidget.prototype.member_response = function(data) {
+        AuthListWidget.prototype.member_response = function(data) {
             var msg;
             this.clear_errors();
             this.clear_input();
@@ -233,7 +236,7 @@ such that the value can be defined later than this assignment (file load order).
             }
         };
 
-        return authListWidget;
+        return AuthListWidget;
     }(MemberListWidget));
 
     this.AutoEnrollmentViaCsv = (function() {
diff --git a/lms/static/lms/js/spec/main.js b/lms/static/lms/js/spec/main.js
index 85aa5f43ae..2a4b77f506 100644
--- a/lms/static/lms/js/spec/main.js
+++ b/lms/static/lms/js/spec/main.js
@@ -51,7 +51,7 @@
             'squire': 'xmodule_js/common_static/js/vendor/Squire',
             'jasmine-imagediff': 'xmodule_js/common_static/js/vendor/jasmine-imagediff',
             'domReady': 'xmodule_js/common_static/js/vendor/domReady',
-            mathjax: '//cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',  // eslint-disable-line max-len
+            mathjax: '//cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?config=TeX-MML-AM_SVG&delayStartupUntil=configured',  // eslint-disable-line max-len
             'youtube': '//www.youtube.com/player_api?noext',
             'coffee/src/ajax_prefix': 'xmodule_js/common_static/coffee/src/ajax_prefix',
             'js/instructor_dashboard/student_admin': 'js/instructor_dashboard/student_admin',