Add shadow opacity to dropdowns and pop-ups

[melissaperreault]

PR Summary:

Increase the elevation of dropdowns and pop-ups components by default.

Why are these changes introduced?

Improves the elevation of this type of component in general for Dawn only. Feels aligned to add some depth considering what we introduced on cards hover with larger shadows. We saw this opportunity because of the UI details for the new Variant list section.

Visual impact on existing themes

Navigation dropdowns, pop-up modals, and cart pop-ups will receive a soft shadow of 5%.

Testing steps/scenarios

• Navigate the store and notice the nav dropdown
• Open the search dropdown
• Add a product to cart
• Validate the Dropdowns and pop-ups shadow value in Theme settings

Demo links

• Editor

Checklist

• Added PR summary for release notes
• Requested review from UX (Only for changes that are affecting the experience or perceivable visual details)
• Created a ticket for the help.shopify.com documentation team about updates to theme settings. (Internal-only task)
• Followed theme code principles
• Linted with Theme Check
• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility

[kjellr]

I like this change — I think it makes sense to add a small amount of depth here.

Can we make this 5% instead of 10% though? It's minor, but I feel the more subtle shadow matches the light aesthetic of the theme a little more closely:

10%	5%