Suggestion: use a primary "accent" color for buttons

[Simon-Laux]

Currently the install & download buttons look like they were disabled, most notable in the darker themes:

maybe something like this:

(maybe a more vibrant color than this?)

[garredow]

Added option for custom accent color in https://github.com/garredow/kaiware/commit/d4d4225429db8c328de4345f202e6f3c49a847f7