fix: improve header visibility in dark terminal themes

[HAOGRE]

Fix: Improve header visibility in dark terminal themes

Problem

In dark terminal themes, the header "✦ ✧ ✦ ✧ CLAUDE CODE USAGE MONITOR ✦ ✧ ✦ ✧" was nearly invisible on certain terminal configurations (particularly iTerm2 with dark backgrounds). The previous color color(117) (light blue, RGB 135,215,255) had insufficient contrast on blue-tinted dark backgrounds.

Root Cause

• color(117) has a perceived brightness of ~196
• Blue is the least visible color to human eyes (sensitivity: green > red > blue)
• Different terminals render ANSI colors differently
• iTerm2 and other terminals with custom color schemes may render bright blue as grayish

Solution

Changed the dark theme header color from:

"header": "color(117)"  # Light blue, insufficient contrast

to:

"header": "bold bright_white"  # Maximum visibility on all dark backgrounds

Changes

• File: src/claude_monitor/terminal/themes.py (line 134)
• Before: "header": "color(117)" - Light blue with 14:1 contrast ratio
• After: "header": "bold bright_white" - Bold bright white for maximum visibility

Benefits

1. ✅ Universal compatibility: Works on all dark terminal themes
2. ✅ Maximum contrast: WCAG AAA compliant
3. ✅ Bold emphasis: Draws attention to the application title
4. ✅ Industry standard: Most CLI tools use white/bright white for important headers

Screenshots

Before — header is nearly invisible on an iTerm2 dark background (--theme dark):

After — header is clearly visible with bold bright white (same terminal, same theme):

Testing

• Tested in iTerm2 (dark theme) — see screenshots above
• Tested in VS Code Terminal (dark theme)
• Tested in Terminal.app (dark mode)
• Verified light theme unaffected (change only touches get_dark_background_theme())
• Verified no other components broken

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Related: This is a complementary fix to PR #204 (which addressed Apple Terminal detection). While PR #204 fixed theme detection for Apple Terminal, this PR fixes the actual color contrast issue that affects visibility regardless of terminal type.

🤖 Generated with Claude Code

https://claude.ai/code/session_01WitcsgcVw81J9hKwdCbZRF

[coderabbitai]

📝 Walkthrough

Walkthrough

The dark background theme's "header" style in themes.py was changed from a light-blue ANSI color to "bold bright_white". No other theme mappings or public interfaces were modified.

Changes

Theme color update

Layer / File(s)	Summary
Dark theme header color change src/claude_monitor/terminal/themes.py	The "header" style in get_dark_background_theme changed from "color(117)" to "bold bright_white".

Estimated code review effort: 1 (Trivial) | ~2 minutes

Estimated code review effort

Estimated code review effort: 1 (Trivial) | ~2 minutes

Suggested reviewers: Maciek-roboblog

Poem

A single hue was swapped with care,
Bright white now bold, a header fair,
One line, one change, no fuss, no fright,
The dark theme shines a crisper light. 🐰✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: improving header visibility in dark terminal themes.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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