Feature: Visual refresh — one charm-reader layout, light + dark themes (ADR-032, #17)
  As a reader who likes a TUI/charm aesthetic
  I want a fresh look with a light and a dark theme
  So that the app feels distinctive and reads well in either mode

  # Direction B (light) + C (dark) are one layout in two palettes (CSS variables),
  # plus a persisted toggle and an OS-preference default. Colours are reviewed via
  # the mockups in docs/sketches/, not unit-tested; these scenarios cover the
  # testable structure. Each maps to a Go test in scenario_coverage_test.go.

  Scenario: Light and dark themes share one layout via CSS variables
    Given the app stylesheet
    When it is rendered
    Then it defines a light palette on the root and a dark palette under data-theme="dark", with no duplicate markup

  Scenario: Without a stored choice the theme follows the OS preference
    Given a visitor with no saved theme
    When the page loads
    Then a prefers-color-scheme dark block applies the dark palette automatically

  Scenario: A persisted toggle switches light and dark
    Given any page
    When it is rendered
    Then it includes a theme-toggle control and a small script that flips data-theme and persists the choice

  Scenario: The expanded card embeds the video player
    Given a summarized video with a valid provider id
    When its card is expanded
    Then the expanded card includes the embedded video player
