Refactor collapsible colors into theme constants with day/night palettes

[Copilot]

The collapsible element used hard-coded colors (#8A3B12, #59230B, white) that sat outside the text/accent theme system, and its readability depended on the page's time-of-day gradient. This PR moves those colors into explicit constants so the element matches the page palette and stays legible at all hours.

• New constants in src/ssr.ts, set alongside textColor/accentColor/focusColor:
  • collapsibleBg
  • collapsibleHoverBg
  • collapsibleText
• Day/night variants use the existing hour branch (day is 07:00–17:59):
  • Night: dark warm brown #2B1D12, hover #4A3220, text #fff4cc (same cream as the night accent).
  • Day: cream #FFF1D6, hover #FFDFA3, text #2B1D12.
• Applied to:
  • .collapsible
  • .active and :hover
  • the :after +/− icon
  • .content
• Contrast: the colors are opaque, so they don't depend on the gradient or the containerBg overlay. By my estimate, text contrast is roughly 10–14:1 in both states, including hover. This has not been measured with a tool.

let collapsibleBg = "#2B1D12";
let collapsibleHoverBg = "#4A3220";
let collapsibleText = "#fff4cc";
// day branch overrides: "#FFF1D6" / "#FFDFA3" / "#2B1D12"

The focus ring colors are unchanged and still contrast with the new backgrounds (white at night, black by day). Not checked in a browser.

[Copilot]

🟢 Approval recommended

The styling is consistently applied and all foreground/background combinations exceed WCAG contrast requirements.

0 open findings

What changed in this PR

Refactors collapsible styling into day/night theme colors for consistent readability.

Changes:

• Adds theme-specific collapsible background, hover, and text colors.
• Applies the palette to buttons, icons, and expanded content.
• Maintains accessible contrast across all states.

File	Description
src/​ssr.ts	Defines and applies day/night collapsible palettes.

🧠 Review effort: Balanced

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