Setting TopBar background colour in Shopify embedded App

Question

I've been trying to figure out how to change the TopBar background colour by following the instructions in the doc here: https://polaris.shopify.com/components/structure/app-provider/theme to no avail.

I've added colours in the theme constant but no changes in the rendered page.

Am I missing something? Any ideas?

Here is the code I use:

import React, {useCallback, useState} from 'react';
import {AppProvider, Avatar, Icon, VisuallyHidden, ActionList, Frame, TopBar} from '@shopify/polaris';
import {ArrowLeftMinor, QuestionMarkMajor} from '@shopify/polaris-icons';

export default function TopBarExample() {
    const [isUserMenuOpen, setIsUserMenuOpen] = useState(false);
    const [isSecondaryMenuOpen, setIsSecondaryMenuOpen] = useState(false);
    const [isSearchActive, setIsSearchActive] = useState(false);
    const [searchValue, setSearchValue] = useState('');

    const toggleIsUserMenuOpen = useCallback(
        () => setIsUserMenuOpen((isUserMenuOpen) => !isUserMenuOpen),
        [],
    );

    const toggleIsSecondaryMenuOpen = useCallback(
        () => setIsSecondaryMenuOpen((isSecondaryMenuOpen) => !isSecondaryMenuOpen),
        [],
    );

    const handleSearchResultsDismiss = useCallback(() => {
        setIsSearchActive(false);
        setSearchValue('');
    }, []);

    const handleSearchChange = useCallback((value) => {
        setSearchValue(value);
        setIsSearchActive(value.length > 0);
    }, []);

    const handleNavigationToggle = useCallback(() => {
        console.log('toggle navigation visibility');
    }, []);

    const theme = {
        colors: {
            surface: '#FFFFFF',
            onSurface: '#212B36',
            interactive: '#da94a4',
            secondary: '#da94a4',
            primary: '#da94a4',
            critical: '#da94a4',
            warning: '#da94a4',
            highlight: '#da94a4',
            success: '#da94a4',
            decorative: '#da94a4',
            background: '#da94a4'
        },
        logo: {
            width: 124,
            topBarSource:
                'https://cdn.ad360.media/shopify/images/ad360_black_horizontal_300px.png',
            url: 'https://www.ad360.media',
            accessibilityLabel: 'Ad360 Shopify App'
        },
    };

    const userMenuMarkup = (
        <TopBar.UserMenu
            actions={[
                {
                    items: [{content: 'Back to Shopify', icon: ArrowLeftMinor}],
                },
                {
                    items: [{content: 'Community forums'}],
                },
            ]}
            name="Menadex"
            detail="Ad360"
            initials="D"
            open={isUserMenuOpen}
            onToggle={toggleIsUserMenuOpen}
        />
    );

    const searchResultsMarkup = (
        <ActionList
            items={[{content: 'Shopify help center'}, {content: 'Community forums'}]}
        />
    );

    const searchFieldMarkup = (
        <TopBar.SearchField
            onChange={handleSearchChange}
            value={searchValue}
            placeholder="Search"
            showFocusBorder
        />
    );

    const secondaryMenuMarkup = (
        <TopBar.Menu
            activatorContent={
                <span>
          <Icon source={QuestionMarkMajor} />
          <VisuallyHidden>Secondary menu</VisuallyHidden>
        </span>
            }
            open={isSecondaryMenuOpen}
            onOpen={toggleIsSecondaryMenuOpen}
            onClose={toggleIsSecondaryMenuOpen}
            actions={[
                {
                    items: [{content: 'Community forums'}],
                },
            ]}
        />
    );

    const topBarMarkup = (
        <TopBar
            showNavigationToggle
            userMenu={userMenuMarkup}
            secondaryMenu={secondaryMenuMarkup}
            searchResultsVisible={isSearchActive}
            searchField={searchFieldMarkup}
            searchResults={searchResultsMarkup}
            onSearchResultsDismiss={handleSearchResultsDismiss}
            onNavigationToggle={handleNavigationToggle}
        />
    );

    return (
        <div style={{height: '250px'}}>
            <AppProvider
                theme={theme}
                i18n={{
                    Polaris: {
                        Avatar: {
                            label: 'Avatar',
                            labelWithInitials: 'Avatar with initials {initials}',
                        },
                        Frame: {skipToContent: 'Skip to content'},
                        TopBar: {
                            toggleMenuLabel: 'Toggle menu',
                            SearchField: {
                                clearButtonLabel: 'Clear',
                                search: 'Search',
                            },
                        },
                    },
                }}
            >
                <Frame topBar={topBarMarkup} />
            </AppProvider>
        </div>
    );
}