diff --git a/src/core/constants.ts b/src/core/constants.ts
index 7e6f45e98..8330e31d9 100644
--- a/src/core/constants.ts
+++ b/src/core/constants.ts
@@ -38,10 +38,18 @@ export class CoreConstants {
     /* eslint-disable max-len */
 
     static readonly SECONDS_YEAR = 31536000;
+    static readonly SECONDS_MONTH = 2592000;
     static readonly SECONDS_WEEK = 604800;
     static readonly SECONDS_DAY = 86400;
     static readonly SECONDS_HOUR = 3600;
     static readonly SECONDS_MINUTE = 60;
+    static readonly MILLISECONDS_YEAR = 31536000000;
+    static readonly MILLISECONDS_MONTH = 2592000000;
+    static readonly MILLISECONDS_WEEK = 604800000;
+    static readonly MILLISECONDS_DAY = 86400000;
+    static readonly MILLISECONDS_HOUR = 3600000;
+    static readonly MILLISECONDS_MINUTE = 60000;
+    static readonly MILLISECONDS_SECOND = 1000;
     static readonly WIFI_DOWNLOAD_THRESHOLD = 104857600; // 100MB.
     static readonly DOWNLOAD_THRESHOLD = 10485760; // 10MB.
     static readonly MINIMUM_FREE_SPACE = 10485760; // 10MB.
@@ -131,7 +139,7 @@ export class CoreConstants {
 
 }
 
-type EnvironmentConfig = {
+export interface EnvironmentConfig {
     app_id: string;
     appname: string;
     versioncode: number;
@@ -167,7 +175,7 @@ type EnvironmentConfig = {
     forceOpenLinksIn: 'app' | 'browser';
 };
 
-type EnvironmentBuild = {
+export interface EnvironmentBuild {
     version: string;
     isProduction: boolean;
     isTesting: boolean;
diff --git a/src/core/singletons/math.ts b/src/core/singletons/math.ts
new file mode 100644
index 000000000..1c32c947f
--- /dev/null
+++ b/src/core/singletons/math.ts
@@ -0,0 +1,32 @@
+// (C) Copyright 2015 Moodle Pty Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/**
+ * Singleton with helper functions for math operations.
+ */
+export class CoreMath {
+
+    /**
+     * Clamp a value between a minimum and a maximum.
+     *
+     * @param value Original value.
+     * @param min Minimum value.
+     * @param max Maximum value.
+     * @return Clamped value.
+     */
+    static clamp(value: number, min: number, max: number): number {
+        return Math.min(Math.max(value, min), max);
+    }
+
+}
diff --git a/src/core/singletons/object.ts b/src/core/singletons/object.ts
index 8f6bf1fa3..0b3dbbc38 100644
--- a/src/core/singletons/object.ts
+++ b/src/core/singletons/object.ts
@@ -21,6 +21,17 @@ export type CoreObjectWithoutEmpty<T> = {
  */
 export class CoreObject {
 
+    /**
+     * Check if two objects have the same shape and the same leaf values.
+     *
+     * @param a First object.
+     * @param b Second object.
+     * @return Whether objects are equal.
+     */
+    static deepEquals(a: unknown, b: unknown): boolean {
+        return JSON.stringify(a) === JSON.stringify(b);
+    }
+
     /**
      * Check whether the given object is empty.
      *
diff --git a/src/theme/globals.variables.scss b/src/theme/globals.variables.scss
index c0c8e0eb4..327dd8f23 100644
--- a/src/theme/globals.variables.scss
+++ b/src/theme/globals.variables.scss
@@ -161,3 +161,12 @@ $screen-breakpoints: (
 ) !default;
 
 $breakpoint-tablet: map-get($screen-breakpoints, tablet), !default;
+
+/*
+ * Z-indexes.
+ *
+ * https://github.com/ionic-team/ionic-framework/blob/master/core/src/themes/ionic.globals.scss
+ */
+
+$z-index-overlay: 1001;
+$z-index-overlay-wrapper: 10;
diff --git a/src/theme/theme.base.scss b/src/theme/theme.base.scss
index 1e33ab0ef..a3b41bb81 100644
--- a/src/theme/theme.base.scss
+++ b/src/theme/theme.base.scss
@@ -37,6 +37,14 @@
     flex-direction: row;
 }
 
+.margin-bottom-sm { margin-bottom: 8px; }
+.margin-bottom-md { margin-bottom: 12px; }
+
+.font-bold { font-weight: bold; }
+.font-italic { font-style: italic; }
+.font-lg { font-size: 1.7rem; }
+.font-sm { font-size: 1.2rem; }
+
 // Correctly inherit ion-text-wrap onto labels.
 ion-item.ion-text-wrap ion-label {
     white-space: normal !important;