html - css3 drop shadow property left right bottom - Stack Overflow
ISOLATING CSS BOX SHADOWS
css - How to create a drop shadow only on one side of an element? - Stack Overflow
3 ways to style CSS box-shadow effects - LogRocket Blog
Derek Briggs on Twitter: "To recap - use a 1px slightly transparent box shadow as a border instead of a traditional css border on elements with shadows to get a gradient border