Preview:
#page .page-section {position: sticky!important; top: 0px!important} html {scroll-behavior: smooth} 

Here is the code from this tutorial with a little bit of a shadow to create even more depth between these pages sections. 

#page .page-section {position: sticky!important; top: 0px; box-shadow: 5px 5px 15px rgba(0,0,0,0.8)!important} html {scroll-behavior: smooth}
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Tip: You can change the style, width & colours of the snippet with the inspect tool before clicking Download!

Click to optimize width for Twitter