Refactor Website CSS: eliminate duplication, add CSS variables

[Copilot]

Changes proposed in this pull request

• Replaced hardcoded #2b3137 with --ifm-background-dark CSS variable (3 instances)
• Replaced hardcoded 1060px with --content-max-width CSS variable (2 instances)
• Removed unused docs/styles.module.css containing duplicate shield styles
• Removed unused styles import from introduction.mdx
• Fixed trailing whitespace in custom.css

Related issue(s)

• N/A (Code quality improvements)

Copilot generated summary

Copilot summary

This PR improves CSS maintainability in the Website folder by consolidating duplicate values into CSS variables and removing unused code. The dark gray background color (#2b3137) and content max-width (1060px) were hardcoded in multiple locations and are now defined as reusable CSS variables (--ifm-background-dark and --content-max-width). An unused duplicate CSS file containing shield styles was removed along with its orphaned import.

Files changed:

• Website/src/css/custom.css - Added CSS variables, fixed formatting
• Website/src/pages/styles.module.css - Updated to use CSS variables
• Website/docs/styles.module.css - Removed (duplicate, unused)
• Website/docs/introduction.mdx - Removed unused import

To-Do

• Update documentation to reflect this changes
• Update changelog to reflect this changes

Contributing

By submitting this pull request, I confirm the following:

• I have read and understood the contributing guidelines and the code of conduct.
• I have have added my name, username or email to the contributors list or don't want to.
• The code or resource is compatible with the GNU General Public License v3.0.

Original prompt

Review the CSS inside the Website folder.

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