[chores] Use theme colors from openwisp-utils variables #1162
Description
Is your feature request related to a problem? Please describe.
Currently, theme colors in this repository are defined explicitly in various UI components and style files. This makes it harder to maintain consistent styling and propagate changes across the OpenWISP project.
Describe the solution you'd like
Refactor the codebase to use the theme color variables defined in openwisp-utils#516, rather than hardcoded color values. This will ensure unified theming and simplify updates to the color palette in the future.