docs: Add Aster's notebook to showcase.md (#912)

Aster Hu

2024-02-22 916aedce40864a485724d9df78879e8d130beab3

 quartz/styles/variables.scss

@@ -5,4 +5,5 @@
$topSpacing: 6rem;
$fullPageWidth: $pageWidth + 2 * $sidePanelWidth;
$boldWeight: 700;
$semiBoldWeight: 600;
$normalWeight: 400;