feat(icon): more elegant, adjust the opacity of the expand button to 32%

[ForrestSu]

What's this PR do?

• adjust the opacity of the expand button to 32%

What are the relevant Git tickets?

None

Screenshots (if appropriate)

• Bright Theme effect

• Dark Theme effect

Any background context you want to provide? (if appropriate)

idea: less conspicuous, overall more coordinated

[jwhitley]

That looks really nice. That said, this variation measures out to a WCAG contrast of ~1.7 for both the light and dark variants – far below the accessible minimum contrast of 4.0. I.e. people with vision issues, often just due to age, won't be able to make out that icon.

My suggestion: add an option to toggle back to the original (or at least, higher) contrast icon.