diff --git a/app/javascript/mastodon/components/modal_shell/redesign.module.scss b/app/javascript/mastodon/components/modal_shell/redesign.module.scss
new file mode 100644
index 00000000000..01f99a914f0
--- /dev/null
+++ b/app/javascript/mastodon/components/modal_shell/redesign.module.scss
@@ -0,0 +1,38 @@
+@use '@/styles/mastodon/mixins';
+
+.modal {
+  @include mixins.elevation-1;
+
+  border-radius: var(--radius-xl);
+  background: var(--color-bg-primary);
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-md);
+  padding: var(--space-md);
+  pointer-events: auto;
+  user-select: text;
+  overflow: hidden;
+}
+
+.modalElevated {
+  @include mixins.elevation-2;
+}
+
+.title {
+  @include mixins.type-heading-sm;
+}
+
+.actions {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: var(--space-md);
+}
+
+.actionsLeft {
+  justify-content: flex-start;
+}
+
+.actionsRight {
+  justify-content: flex-end;
+}
diff --git a/app/javascript/mastodon/components/modal_shell/redesign.stories.tsx b/app/javascript/mastodon/components/modal_shell/redesign.stories.tsx
new file mode 100644
index 00000000000..ee17187fb1c
--- /dev/null
+++ b/app/javascript/mastodon/components/modal_shell/redesign.stories.tsx
@@ -0,0 +1,57 @@
+import type { Meta, StoryObj } from '@storybook/react-vite';
+
+import { Button } from '../button/redesign';
+
+import type { ModalShellProps } from './redesign';
+import { ModalShell, ModalActions, ModalTitle } from './redesign';
+
+const meta = {
+  title: 'Redesign/Modal',
+  args: {
+    actionAlign: 'stretch',
+    children: 'This is a modal.',
+    elevation: 2,
+    maxWidth: 0,
+  },
+  argTypes: {
+    actionAlign: {
+      control: 'inline-radio',
+      options: ['left', 'right', 'stretch'],
+    },
+    elevation: {
+      control: 'inline-radio',
+      options: [1, 2],
+    },
+  },
+  render({ actionAlign, children, ...props }) {
+    return (
+      <ModalShell {...props}>
+        <ModalTitle>Modal Example</ModalTitle>
+
+        {children
+          .split('\n')
+          .filter((line) => !!line.trim())
+          .map((line, index) => (
+            <p key={index}>{line}</p>
+          ))}
+
+        <ModalActions align={actionAlign}>
+          <Button>Cancel</Button>
+
+          <Button color='neutral'>Save</Button>
+        </ModalActions>
+      </ModalShell>
+    );
+  },
+} satisfies Meta<
+  Pick<ModalShellProps, 'elevation' | 'maxWidth'> & {
+    children: string;
+    actionAlign?: 'left' | 'right' | 'stretch';
+  }
+>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+export const Default: Story = {};
diff --git a/app/javascript/mastodon/components/modal_shell/redesign.tsx b/app/javascript/mastodon/components/modal_shell/redesign.tsx
new file mode 100644
index 00000000000..e224cae091b
--- /dev/null
+++ b/app/javascript/mastodon/components/modal_shell/redesign.tsx
@@ -0,0 +1,101 @@
+import type React from 'react';
+
+import classNames from 'classnames';
+
+import type { PolymorphicProps } from '@/types/polymorphic';
+
+import { NavigationFocusTarget } from '../navigation_focus_target';
+
+import classes from './redesign.module.scss';
+
+export interface ModalShellProps {
+  children: React.ReactNode;
+  className?: string;
+  elevation?: 1 | 2;
+  maxWidth?: number;
+  style?: React.CSSProperties;
+}
+
+export const ModalShell = <As extends React.ElementType>({
+  as: asComp,
+  elevation,
+  className,
+  children,
+  maxWidth,
+  style,
+  ...props
+}: PolymorphicProps<ModalShellProps, As>) => {
+  const Comp = asComp ?? 'div';
+  return (
+    <Comp
+      {...props}
+      className={classNames(
+        className,
+        classes.modal,
+        elevation === 2 && classes.modalElevated,
+      )}
+      style={{
+        maxWidth: maxWidth ? `${maxWidth}px` : undefined,
+        ...style,
+      }}
+    >
+      {children}
+    </Comp>
+  );
+};
+
+type HeadingLevels = 1 | 2 | 3 | 4 | 5 | 6;
+
+type ModalTitleProps = { children: React.ReactNode; level?: HeadingLevels } & (
+  | { noFocus: true }
+  | { noFocus?: false; focusTargetName?: string }
+);
+
+export const ModalTitle: React.FC<
+  ModalTitleProps & React.ComponentPropsWithRef<`h${HeadingLevels}`>
+> = ({ level = 1, children, className, noFocus, ...props }) => {
+  const Header = `h${level}` as const;
+  if (!noFocus) {
+    return (
+      <NavigationFocusTarget as={Header} {...props}>
+        {children}
+      </NavigationFocusTarget>
+    );
+  }
+  return (
+    <Header {...props} className={classNames(className, classes.title)}>
+      {children}
+    </Header>
+  );
+};
+
+export const ModalActions = <As extends React.ElementType>({
+  align,
+  as: asComp,
+  children,
+  className,
+  ...props
+}: PolymorphicProps<
+  {
+    align?: 'left' | 'right' | 'stretch';
+    children?: React.ReactNode;
+    className?: string;
+  },
+  As
+>) => {
+  const Comp = asComp ?? 'div';
+
+  return (
+    <Comp
+      {...props}
+      className={classNames(
+        className,
+        classes.actions,
+        align === 'left' && classes.actionsLeft,
+        align === 'right' && classes.actionsRight,
+      )}
+    >
+      {children}
+    </Comp>
+  );
+};
diff --git a/app/javascript/types/polymorphic.ts b/app/javascript/types/polymorphic.ts
index e58aa7b75ee..32c948b992f 100644
--- a/app/javascript/types/polymorphic.ts
+++ b/app/javascript/types/polymorphic.ts
@@ -38,7 +38,7 @@ type ElementRef<As extends ElementType> =
  * Merge additional props with intrinsic/element props for `as`.
  * Additional props win on conflicts.
  */
-type PolymorphicProps<
+type OldPolymorphicProps<
   As extends ElementType,
   AdditionalProps extends object = object,
 > = AdditionalProps &
@@ -52,7 +52,9 @@ type PolymorphicWithRef<
   DefaultAs extends ElementType,
   AdditionalProps extends object = object,
 > = <As extends ElementType = DefaultAs>(
-  props: PolymorphicProps<As, AdditionalProps> & { ref?: Ref<ElementRef<As>> },
+  props: OldPolymorphicProps<As, AdditionalProps> & {
+    ref?: Ref<ElementRef<As>>;
+  },
 ) => ReactElement | null;
 
 /**
@@ -64,12 +66,22 @@ type PolyRefFunction = <
 >(
   render: ForwardRefRenderFunction<
     ElementRef<DefaultAs>,
-    PolymorphicProps<DefaultAs, AdditionalProps>
+    OldPolymorphicProps<DefaultAs, AdditionalProps>
   >,
 ) => PolymorphicWithRef<DefaultAs, AdditionalProps> &
-  ForwardRefExoticComponent<PolymorphicProps<DefaultAs, AdditionalProps>>;
+  ForwardRefExoticComponent<OldPolymorphicProps<DefaultAs, AdditionalProps>>;
 
 /**
  * Polymorphic `forwardRef` function.
  */
 export const polymorphicForwardRef = forwardRef as PolyRefFunction;
+
+// Use this for modern React 19 props
+
+export type PolymorphicProps<
+  AdditionalProps extends object,
+  As extends React.ElementType,
+> = {
+  as?: As;
+} & Omit<React.ComponentPropsWithoutRef<As>, keyof AdditionalProps | 'as'> &
+  AdditionalProps;