diff --git a/src/addons/qtype/calculated/component/addon-qtype-calculated.html b/src/addons/qtype/calculated/component/addon-qtype-calculated.html
index 9767e13cc..d8910df93 100644
--- a/src/addons/qtype/calculated/component/addon-qtype-calculated.html
+++ b/src/addons/qtype/calculated/component/addon-qtype-calculated.html
@@ -55,7 +55,7 @@
 <!-- Template for units entered using radio buttons. -->
 <ng-template #radioUnits>
     <ion-radio-group [(ngModel)]="question!.unit" [name]="question!.optionsName">
-        <ion-item class="ion-text-wrap" *ngFor="let option of question!.options">
+        <ion-item class="ion-text-wrap" *ngFor="let option of question!.options" lines="none">
             <ion-radio [value]="option.value" [disabled]="option.disabled || question!.input?.readOnly"
                 [color]="question!.input?.correctIconColor">
                 {{ option.text }}
diff --git a/src/addons/qtype/multichoice/component/addon-qtype-multichoice.html b/src/addons/qtype/multichoice/component/addon-qtype-multichoice.html
index bd1b653ad..ec262e32c 100644
--- a/src/addons/qtype/multichoice/component/addon-qtype-multichoice.html
+++ b/src/addons/qtype/multichoice/component/addon-qtype-multichoice.html
@@ -41,7 +41,7 @@
 
     <!-- Radio buttons for single choice. -->
     <ion-radio-group *ngIf="!question.multi" [(ngModel)]="question.singleChoiceModel" [name]="question.optionsName">
-        <ion-item class="ion-text-wrap answer" *ngFor="let option of question.options">
+        <ion-item class="ion-text-wrap answer" *ngFor="let option of question.options" lines="none">
             <ion-radio [value]="option.value" [disabled]="option.disabled"
                 [color]='(option.isCorrect === 1 ? "success": "") + (option.isCorrect === 0 ? "danger": "")'>
                 <div>
diff --git a/src/theme/components/ion-action-sheet.scss b/src/theme/components/ion-action-sheet.scss
index c76df351e..d89728cd3 100644
--- a/src/theme/components/ion-action-sheet.scss
+++ b/src/theme/components/ion-action-sheet.scss
@@ -35,3 +35,16 @@ ion-action-sheet {
         }
     }
 }
+
+// File uploader.
+.action-sheet-button input.core-fileuploader-file-handler-input {
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    min-width: 100%;
+    opacity: 0;
+    z-index: 100;
+    cursor: pointer;
+}
diff --git a/src/theme/components/ion-alert.scss b/src/theme/components/ion-alert.scss
index fef0eec00..74c255a07 100644
--- a/src/theme/components/ion-alert.scss
+++ b/src/theme/components/ion-alert.scss
@@ -1,12 +1,75 @@
+@keyframes scaleFrom0 {
+    from {
+        /* More performant than animating `width` */
+        transform: scaleX(0);
+    }
+}
+
 ion-alert {
+    --border-radius: var(--modal-radius);
+
+    &.md, &.ios {
+        --max-width: 80%;
+
+        @include media-breakpoint-up(md) {
+            --max-width: 384px;
+        }
+    }
+
+    .alert-wrapper {
+        overflow: auto;
+        border-radius: var(--border-radius) !important;
+
+        button.alert-button.alert-button-role-destructive {
+            color: var(--danger);
+        }
+
+    }
+
+    .alert-message {
+        user-select: text;
+        flex-shrink: 0;
+
+        ion-card {
+            margin: 0;
+            margin-top: 10px;
+        }
+
+    }
+
     &.md .alert-button {
         // Remove padding from alert buttons, they already have min accessibility height.
         padding-top: 0px;
         padding-bottom: 0px;
     }
 
+    .alert-button.timed-button{
+        position: relative;
+
+        &::before {
+            content: '';
+            position: absolute;
+            width: 100%;
+            left: 0;
+            right: 0;
+            bottom: 0;
+            top: 0;
+            background-color: var(--primary-tint);
+            animation: scaleFrom0 10s forwards linear;
+            transform-origin: left;
+            @include rtl() {
+                transform-origin: right;
+            }
+            z-index: -1;
+        }
+    }
+
     &.core-alert-force-on-top {
         z-index: 100000 !important;
     }
 
+    &.core-nohead .alert-head,
+    .alert-head:empty {
+        padding-bottom: 0;
+    }
 }
diff --git a/src/theme/components/ion-button.scss b/src/theme/components/ion-button.scss
index 0ff8ee7fa..6a6f7ab71 100644
--- a/src/theme/components/ion-button.scss
+++ b/src/theme/components/ion-button.scss
@@ -17,6 +17,10 @@ ion-button {
         color: inherit;
     }
 
+    &.button-disabled {
+        opacity: var(--mdl-button-disabled-opacity) !important;
+    }
+
     &.button-outline {
         --border-width: var(--core-input-border-width);
         --border-color: var(--core-input-stroke);
diff --git a/src/theme/components/ion-checkbox.scss b/src/theme/components/ion-checkbox.scss
index bff03e79d..f43b45807 100644
--- a/src/theme/components/ion-checkbox.scss
+++ b/src/theme/components/ion-checkbox.scss
@@ -1,5 +1,26 @@
-ion-checkbox {
-    &.checkbox-disabled::part(label) {
-        opacity: 0.8;
+
+// Checkbox.
+ion-checkbox,
+input[type=checkbox] {
+    --border-radius: 2px;
+    --border-width: 2px;
+    --outer-border-width: 2px;
+    --border-style: solid;
+    --size: 20px;
+
+    &:not(.ion-color) {
+        --border-color-checked: var(--text-color);
+        --checkbox-background-checked: var(--text-color);
+        --checkmark-color: var(--contrast-background);
     }
 }
+
+ion-checkbox {
+    &.checkbox-disabled::part(label) {
+        opacity: var(--mdl-input-disabled-opacity);
+    }
+}
+
+.ios input[type=checkbox] {
+    --outer-border-width: 1px;
+}
diff --git a/src/theme/components/ion-datetime.scss b/src/theme/components/ion-datetime.scss
new file mode 100644
index 000000000..c91d916f7
--- /dev/null
+++ b/src/theme/components/ion-datetime.scss
@@ -0,0 +1,14 @@
+ion-item.item-label-stacked ion-datetime-button {
+    margin-top: 8px;
+    margin-bottom: 8px;
+    align-self: self-end;
+}
+
+ion-datetime-button p {
+    margin-top: 4px;
+    margin-bottom: 4px;
+}
+
+ion-datetime.datetime-disabled {
+    opacity: var(--mdl-input-disabled-opacity) !important;
+}
diff --git a/src/theme/components/ion-fab.scss b/src/theme/components/ion-fab.scss
new file mode 100644
index 000000000..f6eee8464
--- /dev/null
+++ b/src/theme/components/ion-fab.scss
@@ -0,0 +1,35 @@
+
+// Hide close button because when present is read on voice over.
+ion-fab[core-fab] {
+    ion-fab-button::part(close-icon) {
+        display: none;
+    }
+}
+
+// The following 4 selectors can probably be removed after Ionic migration to 7+
+ion-fab.fab-horizontal-start {
+    left: calc(10px + var(--ion-safe-area-right, 0px));
+}
+
+&[dir=rtl] ion-fab.fab-horizontal-start {
+    right: calc(10px + var(--ion-safe-area-right, 0px));
+    left: unset
+}
+
+ion-fab.fab-horizontal-end {
+    right: calc(10px + var(--ion-safe-area-right, 0px));
+}
+
+&[dir=rtl] ion-fab.fab-horizontal-end {
+    left: calc(10px + var(--ion-safe-area-right, 0px));
+    right: unset
+}
+
+ion-content.has-collapsible-footer ion-fab {
+    bottom: calc(var(--core-collapsible-footer-height, 0px) + 10px);
+    @include core-transition(all, 200ms);
+}
+
+ion-fab-button {
+    --box-shadow: 0 3px 5px -1px rgb(0 0 0 / 20%), 0 6px 10px 0 rgb(0 0 0 / 14%), 0 1px 18px 0 rgb(0 0 0 / 12%);
+}
diff --git a/src/theme/components/ion-input.scss b/src/theme/components/ion-input.scss
index da82c4ec4..6675453f4 100644
--- a/src/theme/components/ion-input.scss
+++ b/src/theme/components/ion-input.scss
@@ -1,5 +1,5 @@
 ion-input {
     &.input-disabled.md, &.input-disabled.ios {
-        opacity: 0.8;
+        opacity: var(--mdl-input-disabled-opacity);
     }
 }
diff --git a/src/theme/components/ion-item.scss b/src/theme/components/ion-item.scss
index 26c0c28bc..a6c4a2ce4 100644
--- a/src/theme/components/ion-item.scss
+++ b/src/theme/components/ion-item.scss
@@ -19,7 +19,8 @@ ion-item.item {
     }
 
     &.ion-valid,
-    &.ion-invalid {
+    &.ion-invalid,
+    &.item-has-interactive-control {
         &.item-lines-default {
             --border-width: 0 0 1px 0;
         }
diff --git a/src/theme/components/ion-radio.scss b/src/theme/components/ion-radio.scss
index ef14fe5aa..80a361faa 100644
--- a/src/theme/components/ion-radio.scss
+++ b/src/theme/components/ion-radio.scss
@@ -1,5 +1,63 @@
-ion-radio {
-    &.radio-disabled::part(label) {
-        opacity: 0.8;
+
+// Radio.
+ion-radio,
+input[type=radio],
+.select-alert .alert-radio-icon {
+    --border-radius: 50%;
+    --border-width: 2px;
+    --outer-border-width: 2px;
+    --border-style: solid;
+    --size: 20px;
+
+    &:not(.ion-color) {
+        --color: var(--text-color);
+        --color-checked: var(--color);
+    }
+}
+
+.ios ion-radio,
+.ios input[type=radio],
+.select-alert.ios .alert-radio-icon {
+    --border-width: 1px;
+    --outer-border-width: 1px;
+}
+
+.ios ion-radio {
+    &::part(container) {
+        width: var(--size);
+        height: var(--size);
+
+        margin: 0px;
+        border-radius: var(--border-radius);
+        border-width: var(--outer-border-width);
+        border-style: var(--border-style);
+        border-color: var(--color);
+    }
+
+    &::part(mark) {
+        border-radius: var(--inner-border-radius);
+        width: calc(50% + var(--outer-border-width));
+        height: calc(50% + var(--outer-border-width));
+        transform: scale3d(0, 0, 0);
+        transition: transform 280ms cubic-bezier(.4, 0, .2, 1);
+        background: var(--contrast-background);
+        border: 0 !important;
+    }
+
+    &.radio-checked {
+        &::part(container) {
+            border-color: var(--color);
+            background: var(--color);
+        }
+
+        &::part(mark) {
+            transform: scale3d(1, 1, 1);
+        }
+    }
+}
+
+ion-radio {
+    &.radio-disabled::part(label) {
+        opacity: var(--mdl-input-disabled-opacity);
     }
 }
diff --git a/src/theme/components/ion-select.scss b/src/theme/components/ion-select.scss
index 43a07803c..597e47f11 100644
--- a/src/theme/components/ion-select.scss
+++ b/src/theme/components/ion-select.scss
@@ -7,7 +7,7 @@ ion-select {
         opacity: 1;
     }
     &.select-disabled {
-        opacity: 0.8;
+        opacity: var(--mdl-input-disabled-opacity);
     }
 }
 
diff --git a/src/theme/theme.base.scss b/src/theme/theme.base.scss
index 7063ca260..43e6b0cae 100644
--- a/src/theme/theme.base.scss
+++ b/src/theme/theme.base.scss
@@ -111,10 +111,6 @@ button,
     }
 }
 
-ion-fab-button {
-    --box-shadow: 0 3px 5px -1px rgb(0 0 0 / 20%), 0 6px 10px 0 rgb(0 0 0 / 14%), 0 1px 18px 0 rgb(0 0 0 / 12%);
-}
-
 [role="button"],
 .clickable {
     cursor: pointer;
@@ -123,14 +119,14 @@ ion-fab-button {
     [disabled],
     [aria-disabled="true"] {
         cursor: default;
-        opacity: .4;
+        opacity: var(--mdl-button-disabled-opacity);
         pointer-events: none;
     }
 }
 
 button[disabled] {
     cursor: default;
-    opacity: .4;
+    opacity: var(--mdl-button-disabled-opacity);
     pointer-events: none;
 }
 
@@ -188,72 +184,6 @@ div.core-iframe-network-error {
     left: -15%;
 }
 
-ion-alert.core-nohead .alert-head,
-ion-alert .alert-head:empty {
-    padding-bottom: 0;
-}
-
-@keyframes scaleFrom0 {
-    from {
-        /* More performant than animating `width` */
-        transform: scaleX(0);
-    }
-}
-
-ion-alert .alert-button.timed-button{
-    position: relative;
-
-    &::before {
-        content: '';
-        position: absolute;
-        width: 100%;
-        left: 0;
-        right: 0;
-        bottom: 0;
-        top: 0;
-        background-color: var(--primary-tint);
-        animation: scaleFrom0 10s forwards linear;
-        transform-origin: left;
-        @include rtl() {
-            transform-origin: right;
-        }
-        z-index: -1;
-    }
-}
-
-ion-alert {
-    --border-radius: var(--modal-radius);
-
-    &.md, &.ios {
-        --max-width: 80%;
-
-        @include media-breakpoint-up(md) {
-            --max-width: 384px;
-        }
-    }
-
-    .alert-wrapper {
-        overflow: auto;
-        border-radius: var(--border-radius) !important;
-
-        button.alert-button.alert-button-role-destructive {
-            color: var(--danger);
-        }
-
-    }
-
-    .alert-message {
-        user-select: text;
-        flex-shrink: 0;
-
-        ion-card {
-            margin: 0;
-            margin-top: 10px;
-        }
-
-    }
-}
-
 // Ionic list.
 ion-list {
     padding: 0 !important;
@@ -545,103 +475,12 @@ ion-content.limited-width > :not([slot]) {
     min-height: 100%;
 }
 
-// Radio.
-ion-radio,
-input[type=radio],
-.select-alert .alert-radio-icon {
-    --border-radius: 50%;
-    --border-width: 2px;
-    --outer-border-width: 2px;
-    --border-style: solid;
-    --size: 20px;
-
-    &:not(.ion-color) {
-        --color: var(--text-color);
-        --color-checked: var(--color);
-    }
-}
-
-.ios ion-radio,
-.ios input[type=radio],
-.select-alert.ios .alert-radio-icon {
-    --border-width: 1px;
-    --outer-border-width: 1px;
-}
-
-.ios ion-radio {
-    &::part(container) {
-        width: var(--size);
-        height: var(--size);
-
-        margin: 0px;
-        border-radius: var(--border-radius);
-        border-width: var(--outer-border-width);
-        border-style: var(--border-style);
-        border-color: var(--color);
-    }
-
-    &::part(mark) {
-        border-radius: var(--inner-border-radius);
-        width: calc(50% + var(--outer-border-width));
-        height: calc(50% + var(--outer-border-width));
-        transform: scale3d(0, 0, 0);
-        transition: transform 280ms cubic-bezier(.4, 0, .2, 1);
-        background: var(--contrast-background);
-        border: 0 !important;
-    }
-
-    &.radio-checked {
-        &::part(container) {
-            border-color: var(--color);
-            background: var(--color);
-        }
-
-        &::part(mark) {
-            transform: scale3d(1, 1, 1);
-        }
-    }
-}
-
-
-// Checkbox.
-ion-checkbox,
-input[type=checkbox] {
-    --border-radius: 2px;
-    --border-width: 2px;
-    --outer-border-width: 2px;
-    --border-style: solid;
-    --size: 20px;
-
-    &:not(.ion-color) {
-        --border-color-checked: var(--text-color);
-        --checkbox-background-checked: var(--text-color);
-        --checkmark-color: var(--contrast-background);
-    }
-}
-
-.ios input[type=checkbox] {
-    --outer-border-width: 1px;
-}
-
 ion-badge {
     line-height: 1.1;
     padding: 2px 8px;
     border-radius: var(--mdl-shape-borderRadius-lg);
 }
 
-// File uploader.
-.action-sheet-button input.core-fileuploader-file-handler-input {
-    position: absolute;
-    top: 0;
-    bottom: 0;
-    left: 0;
-    right: 0;
-    min-width: 100%;
-    opacity: 0;
-    z-index: 100;
-    cursor: pointer;
-}
-
 .core-anchor, core-format-text a {
     color: var(--core-link-color);
     cursor: pointer;
@@ -721,37 +560,6 @@ textarea:not([core-auto-rows]) {
     height: 200px;
 }
 
-// Hide close button because when present is read on voice over.
-ion-fab[core-fab] {
-    ion-fab-button::part(close-icon) {
-        display: none;
-    }
-}
-
-// The following 4 selectors can probably be removed after Ionic migration to 7+
-ion-fab.fab-horizontal-start {
-    left: calc(10px + var(--ion-safe-area-right, 0px));
-}
-
-[dir=rtl] ion-fab.fab-horizontal-start {
-    right: calc(10px + var(--ion-safe-area-right, 0px));
-    left: unset
-}
-
-ion-fab.fab-horizontal-end {
-    right: calc(10px + var(--ion-safe-area-right, 0px));
-}
-
-[dir=rtl] ion-fab.fab-horizontal-end {
-    left: calc(10px + var(--ion-safe-area-right, 0px));
-    right: unset
-}
-
-ion-content.has-collapsible-footer ion-fab {
-    bottom: calc(var(--core-collapsible-footer-height, 0px) + 10px);
-    @include core-transition(all, 200ms);
-}
-
 .core-media-adapt-width {
     max-width: 100%;
 }
@@ -766,10 +574,8 @@ audio.core-media-adapt-width {
 
 // Disabled items.
 ion-item.item-disabled,
-ion-button.button-disabled,
-ion-item.item-interactive-disabled:not(.item-multiple-inputs) ion-label,
-ion-datetime.datetime-disabled {
-    opacity: .65 !important;
+ion-item.item-interactive-disabled:not(.item-multiple-inputs) ion-label {
+    opacity: var(--mdl-item-disabled-opacity) !important;
 }
 
 ion-item-divider.item,
@@ -803,7 +609,7 @@ ion-input input,
 ion-textarea,
 core-rich-text-editor {
     --placeholder-color: var(--ion-placeholder-color);
-    --placeholder-opacity: .65;
+    --placeholder-opacity: var(--mdl-placeholder-opacity);
 }
 
 // Disable scroll on parent ion contents to enabled PTR on the ones inside the splitview. See split-view component for more info.
@@ -992,18 +798,6 @@ video::-webkit-media-text-track-display {
     display: none !important;
 }
 
-// Ion Datetime
-ion-item.item-label-stacked ion-datetime-button {
-    margin-top: 8px;
-    margin-bottom: 8px;
-    align-self: self-end;
-}
-
-ion-datetime-button p {
-    margin-top: 4px;
-    margin-bottom: 4px;
-}
-
 .x-scrollable {
     overflow-x: auto;
     display: block;
diff --git a/src/theme/theme.design-system.scss b/src/theme/theme.design-system.scss
index 0d10bf1a6..efc3323fa 100644
--- a/src/theme/theme.design-system.scss
+++ b/src/theme/theme.design-system.scss
@@ -140,6 +140,12 @@ html {
     --mdl-shadow-boxShadow-16: 0px 7px 8px 0px rgb(var(--mdl-shadow-boxShadowColor) / 20%),0px 5px 22px 0px rgb(var(--mdl-shadow-boxShadowColor) / 12%),0px 12px 17px 0px rgb(var(--mdl-shadow-boxShadowColor) / 14%);
     --mdl-shadow-boxShadow-24: 0px 11px 15px 0px rgb(var(--mdl-shadow-boxShadowColor) / 20%), 0px 9px 46px 0px rgb(var(--mdl-shadow-boxShadowColor) / 12%), 0px 24px 38px 0px rgb(var(--mdl-shadow-boxShadowColor) / 14%);
 
+    // ***** OPACITY category ***** //
+    --mdl-button-disabled-opacity: 0.6;
+    --mdl-input-disabled-opacity: 0.6;
+    --mdl-item-disabled-opacity: 0.4;
+    --mdl-placeholder-opacity: 0.6;
+
     // ***** ACCESSIBILITY ***** //
     --a11y-sizing-minTargetSize: 44px;
     --a11y-shadow-focus-borderWidth: 2px;
diff --git a/src/theme/theme.scss b/src/theme/theme.scss
index eee5ac6f5..11ccfb456 100644
--- a/src/theme/theme.scss
+++ b/src/theme/theme.scss
@@ -36,6 +36,8 @@ html {
     @import "components/ion-checkbox.scss";
     @import "components/ion-chip.scss";
     @import "components/ion-content.scss";
+    @import "components/ion-datetime.scss";
+    @import "components/ion-fab.scss";
     @import "components/ion-header.scss";
     @import "components/ion-icon.scss";
     @import "components/ion-input.scss";