It’s because most of the page CSS is being added at the very bottom of the page instead of inside of the head where it should be. This means the HTML is visible for a split second, with a lot of styling missing (known as FOUC). I can see it when I visit the page with browser cache disabled.
Attaching a screenshot to show what I see when the page first loads, and where the CSS is for a lot of the default Bricks styles…
