diff --git a/src/core/classes/modal-lateral-transition.ts b/src/core/classes/modal-lateral-transition.ts
index 45fafb626..95476b607 100644
--- a/src/core/classes/modal-lateral-transition.ts
+++ b/src/core/classes/modal-lateral-transition.ts
@@ -27,7 +27,7 @@ export function CoreModalLateralTransitionEnter(baseEl: HTMLElement): Animation
 
     const otherAnimations: Animation[] = [];
 
-    const backdrop = baseEl.querySelector('ion-backdrop');
+    const backdrop = baseEl.shadowRoot?.querySelector('ion-backdrop');
     if (backdrop) {
         const backdropAnimation = createAnimation()
             .addElement(backdrop)
@@ -36,7 +36,7 @@ export function CoreModalLateralTransitionEnter(baseEl: HTMLElement): Animation
         otherAnimations.push(backdropAnimation);
     }
 
-    const wrapper = baseEl.querySelector('.modal-wrapper');
+    const wrapper = baseEl.shadowRoot?.querySelector('.modal-wrapper');
     if (wrapper) {
         const wrapperAnimation = createAnimation()
             .addElement(wrapper)
@@ -64,7 +64,7 @@ export function CoreModalLateralTransitionLeave(baseEl: HTMLElement): Animation
 
     const otherAnimations: Animation[] = [];
 
-    const backdrop = baseEl.querySelector('ion-backdrop');
+    const backdrop = baseEl.shadowRoot?.querySelector('ion-backdrop');
     if (backdrop) {
         const backdropAnimation = createAnimation()
             .addElement(backdrop)
@@ -73,7 +73,7 @@ export function CoreModalLateralTransitionLeave(baseEl: HTMLElement): Animation
         otherAnimations.push(backdropAnimation);
     }
 
-    const wrapper = baseEl.querySelector('.modal-wrapper');
+    const wrapper = baseEl.shadowRoot?.querySelector('.modal-wrapper');
     if (wrapper) {
         const wrapperAnimation = createAnimation()
             .addElement(wrapper)
diff --git a/src/theme/theme.base.scss b/src/theme/theme.base.scss
index c6ef546ae..2cd899729 100644
--- a/src/theme/theme.base.scss
+++ b/src/theme/theme.base.scss
@@ -680,7 +680,7 @@ body.core-iframe-fullscreen ion-router-outlet {
 }
 
 // Modals.
-.core-modal-fullscreen .modal-wrapper {
+.core-modal-fullscreen::part(content) {
     position: absolute;
     @include position(0 !important, null, null, 0 !important);
     display: block;
@@ -690,11 +690,11 @@ body.core-iframe-fullscreen ion-router-outlet {
 
 .core-modal-transparent {
 
-    ion-backdrop {
+    &::part(backdrop) {
         backdrop-filter: blur(8px);
     }
 
-    .modal-wrapper {
+    &::part(content) {
         backdrop-filter: blur(12px);
         --background: rgba(10, 10, 10, 0.2);
 
@@ -717,7 +717,7 @@ body.core-iframe-fullscreen ion-router-outlet {
     --ion-safe-area-left: 0px;
     --ion-safe-area-right: 0px;
 
-    .modal-wrapper {
+    &::part(content) {
         @include margin-horizontal(var(--modal-lateral-margin), null);
 
         position: absolute;
@@ -729,7 +729,7 @@ body.core-iframe-fullscreen ion-router-outlet {
         box-shadow: 0 28px 48px rgba(0, 0, 0, 0.4);
     }
 
-    ion-backdrop {
+    &::part(backdrop) {
         visibility: visible;
     }
 
@@ -740,10 +740,10 @@ body.core-iframe-fullscreen ion-router-outlet {
 
 .core-modal-transparent-no-filter {
     @extend .core-modal-transparent;
-    ion-backdrop {
+    &::part(backdrop) {
         backdrop-filter: none;
     }
-    .modal-wrapper {
+    &::part(content) {
         backdrop-filter: none;
     }
 }
@@ -1107,7 +1107,7 @@ ion-checkbox,
 input[type=checkbox] {
     --border-radius: 2px;
     --border-color-checked: var(--text-color);
-    --background-checked: var(--text-color);
+    --checkbox-background-checked: var(--text-color);
     --checkmark-color: var(--contrast-background);
     --border-width: 2px;
     --outer-border-width: 2px;
@@ -1318,7 +1318,7 @@ mark, .matchtext {
 }
 
 .core-scanning-qr {
-    .ion-page, .modal-wrapper {
+    .ion-page, ion-modal::part(content) {
         background-color: transparent !important;
         --background: transparent;
     }
@@ -1887,14 +1887,14 @@ ion-modal {
         --box-shadow: none !important;
         pointer-events: none;
 
-        ion-backdrop {
+        &::part(backdrop) {
             display: none;
         }
     }
 }
 
 ion-popover {
-    .popover-wrapper .popover-content {
+    &::part(content) {
         border-radius: var(--modal-radius);
     }
     &.md {
@@ -1903,7 +1903,7 @@ ion-popover {
 
         // Never show backdrop on popovers on Android
         // @todo Apply box shadow on ios and make it transparent too. The main problem is the box arrow.
-        ion-backdrop {
+        &::part(backdrop) {
             background: transparent;
         }
     }
diff --git a/src/theme/theme.light.scss b/src/theme/theme.light.scss
index 4778e4428..60dc20775 100644
--- a/src/theme/theme.light.scss
+++ b/src/theme/theme.light.scss
@@ -146,7 +146,7 @@ html {
     --core-header-buttons-background: var(--core-header-toolbar-background);
     --core-header-buttons-color: var(--core-header-toolbar-color);
 
-    ion-header {
+    ion-header, ion-header.header-md {
         box-shadow: var(--core-header-shadow, none);
         transition: box-shadow 0.5s;