Goal: Design a sidebar-style table of contents for an article.

Steps:

• Use a Codex Card as the sidebar container.
• Add headings (e.g., “Introduction,” “History”) with Codex’s @heading-small style.
• Insert bullet points or Codex list components for subsections.
• Add a subtle border using Codex’s @border-color-base token.
• Skill: Layout organization, list components, borders.