Iteration I2: Administrative Pages. The h1 tag for the admin#index view has contradictory text size classes text-lg and text-4xl. The image in the book is text-lg, which seems to take precedence if you add both.
<h1 class="mx-auto text-lg font-bold text-4xl">Welcome</h1>
Should be
<h1 class="mx-auto text-lg font-bold">Welcome</h1>
If the correct class is text-4xl, the image in the book will also need to be updated.