Add id_prefix parameter to render_argument(), render_group(), and
render_mutex_group() methods. Update render_group_section() to pass
the prefix through to child methods.

This enables unique argument IDs per subcommand (e.g., "load-L" vs
"shell-L") when multiple argparse directives exist on the same page.

- Background for .argparse-argument-name (like code.literal)
- scroll-margin-top for .argparse-argument-wrapper
- Headerlink visibility (hidden by default, visible on hover)
- :target highlight when navigating via URL fragment
- .nv styling in .argparse-argument-meta for default values

Add tests for _generate_argument_id() covering:
- Short/long options, positional arguments
- Multiple names, empty names, prefix handling

Add parametrized HTML rendering tests using NamedTuple:
- MockTranslator and render_argument_to_html() helper
- Verify wrapper div, headerlink, styled defaults
- Test balanced div tags and ID patterns

- Set --color-inline-code-background to #eeeeee in light mode
- Use color-mix with 50% white for .argparse-argument-name in light mode

- Use monokai background (#272822) for both light and dark modes
- Add dark mode media query for prefers-color-scheme support
- Adjust padding to .325rem .6rem and border-radius to .2rem
- Add width: fit-content to .argparse-argument-name
- Set headerlink color to #9ca0a5 in light mode for dark background
- Remove color-mix override (same background for both modes now)

- Use :hover:not(:visited) for headerlink hover states
- Set light mode hover color to #cfd0d0

Add background, border-radius, padding, and font-family to
.argparse-argument-meta .nv to match inline code appearance.

Replace overrides of Furo's --color-inline-code-background with a
custom --argparse-code-background variable (#272822 monokai) to
avoid affecting other inline code styling on the site.

- Increase .argparse-argument-name padding to .485rem .875rem
- Add .argparse-argument-help with padding-block-start for spacing
- Remove unused type: ignore comments in test_nodes.py

- Extract shared font-family into combined .cli-* selector rule
- Merge .cli-option-long and .cli-option-short (identical color)
- Combine hover and :target headerlink visibility rules
- Replace hardcoded #272822 with var(--argparse-code-background)

Use absolute positioning to place the ¶ link outside the dt element
to the right, rather than inline. Hover trigger moved to the wrapper
element so the link appears when hovering anywhere on the argument block.

…ding

Document the new linkable arguments feature with headerlinks,
visual styling improvements, and default value badges