'Return to' button results in a secondary white flash after page initially loads

On the Imera tab, click on the Bestiary 'Learn More'.  Select 'Mammals', then select 'Vir'. 

I added the following code to the code block at the bottom of the page to add 2 buttons. 

<div class="multi-button center">
<div class="sqs-block-button-container" data-animation-role="button">
  <a href="/bestiary-main-page" class="sqs-button-element--secondary sqs-block-button-element">
     Return to Bestiary 
  </a>
</div>

<div class="sqs-block-button-container" data-animation-role="button">
  <a href="/mammal-information-pages" class="sqs-button-element--secondary sqs-block-button-element">
    Return to Mammals
  </a>
</div>
</div>

The 'Return to Bestiary' button works fine and back button navigation on the bestiary page returns me to the 'Vir' page.

Issues:

1. The 'Return to Mammals' button appears to load the Mammal page, then flashes white before loading correctly. 
2. In addition, once the Mammal page finalizes loading, the back button doesn't take me back to the Vir page but leaves me on the Mammal page.

How can I get rid of the secondary white flash? And get the back button functioning correctly?

Hi,

What is site url? We can check easier

Sorry, I thought it was available because it asked for it when I filled out the form.  The site is not published yet.  Will I need to publish it?

Vir Information - Fantasy Creature — The Imerian (squarespace.com)  

Thank you for responding to my inquiry.  🙂