Actually, while this solution works, it does not fix the problem, it fixes the symptom.
And the problem is that your layout/theme.liquid misses the tag, the one like https://github.com/Shopify/dawn/blob/release/11.0.0-rc/layout/theme.liquid#L2 – probably overwritten when the element was pasted.
Because of this there is a bunch of CSS code which does not work as intended.
If you add back the , you’d be able to undo the “solution” code because theme own CSS will work fine.
Also, there is a countdown JS code which can’t find the countdown element and floods console with errors – probably should be removed as well.