CSS Diagnostics Skill

Purpose

Analyze CSS usage across all 44 XHTML chapters to identify:

• Unused selectors (dead code)
• Classes/IDs used in XHTML but missing in CSS
• Conflicting or redundant rules
• Opportunities for stylesheet consolidation

When to Invoke

• User asks "are there unused CSS rules?"
• After completing visual QA audit
• Before final EPUB packaging (to reduce file size)
• User mentions slow rendering or bloated stylesheets
• User asks "which CSS rules are actually used?"

Workflow

Run CSS Coverage Analysis

python3 scripts/css_coverage_analyzer.py \
  --root REBRANDED_OUTPUT \
  --targets docs/REBRANDED_VISUAL_AUDIT.json \
  --out docs/CSS_COVERAGE.md

What it does:

1. Scans all 44 XHTML files for:
   • Classes (class="...")
   • IDs (id="...")
   • Element selectors (h1, p, img, etc.)
2. Parses both CSS files:
   • REBRANDED_OUTPUT/xhtml/styles/style.css (digital)
   • REBRANDED_OUTPUT/xhtml/styles/print-pod.css (POD print)
3. Generates coverage report:
   • Used selectors (appears in both XHTML and CSS)
   • Unused selectors (in CSS but not used in any XHTML)
   • Missing selectors (in XHTML but not defined in CSS)
   • Redundant rules (duplicate declarations)
4. Outputs:
   • docs/CSS_COVERAGE.md (human-readable summary)
   • docs/CSS_COVERAGE.json (detailed machine-readable data)

Interpreting Results

Coverage Summary

CSS Coverage Analysis
=====================

Total selectors defined: 487
Total selectors used: 412
Unused selectors: 75 (15.4%)
Missing definitions: 8 (1.9%)

File sizes:
- style.css: 27.3 KB
- print-pod.css: 9.8 KB
- Combined: 37.1 KB

Metrics:

• <10% unused: Excellent (tight, well-maintained CSS)
• 10-20% unused: Good (normal for evolving projects)
• 20-40% unused: Fair (consider cleanup before publication)
• >40% unused: Poor (significant bloat, requires refactoring)

Unused Selectors

Example output:

Unused Selectors (75 total)
===========================

.legacy-chapter-title { ... }     # Safe to remove
.old-quiz-style { ... }            # Safe to remove
.experimental-layout { ... }       # Safe to remove
.chapter-summary { ... }           # May be used in future chapters

Action items:

1. Review each unused selector
2. Verify it's not used in:
   • Templates (may be used when generating new chapters)
   • Future chapters (planned but not yet created)
   • Print-specific layouts (may only appear in POD version)
3. If confirmed unused:
   • Comment out (for testing)
   • Remove entirely (after testing)

Missing Definitions

Example output:

Missing CSS Definitions (8 total)
=================================

.worksheet-answer-box          # Used in chapters 9, 15, 22
.reflection-prompt             # Used in chapters 11, 16, 27
.smart-goal-template           # Used in chapter 40

Action items:

1. Add definitions to style.css:

   .worksheet-answer-box {
     border: 1px solid #ccc;
     padding: 1em;
     margin: 1em 0;
     background: #f9f9f9;
   }
   

2. Test in visual QA to verify rendering
3. Re-run CSS coverage to confirm

Conflict Detection

Example output:

Potential Conflicts
===================

.chapter-title is defined in:
  - style.css line 147
  - print-pod.css line 89
  (Conflicting font-size values: 2.5rem vs 3rem)

.footnote is defined twice in style.css:
  - Line 203 (font-size: 0.85rem)
  - Line 456 (font-size: 0.9rem)

Action items:

1. Resolve conflicts by:
   • Using media queries (@media print { ... })
   • Removing duplicate definitions
   • Using more specific selectors
2. Test across viewports to ensure no regressions

Optimization Opportunities

After running diagnostics, consider:

1. Remove Unused Selectors

• Backup current CSS: cp style.css style.css.backup
• Remove confirmed dead code
• Re-run visual QA to verify no regressions
• Potential savings: 10-30% file size reduction

2. Consolidate Redundant Rules

/* Before */
h1 { font-family: "Cinzel"; font-weight: 700; }
h2 { font-family: "Cinzel"; font-weight: 700; }
h3 { font-family: "Cinzel"; font-weight: 700; }

/* After */
h1, h2, h3 { font-family: "Cinzel"; font-weight: 700; }

3. Extract Common Patterns

/* Before */
.chapter-intro { margin: 2em 0; padding: 1em; }
.section-intro { margin: 2em 0; padding: 1em; }

/* After */
.intro-block { margin: 2em 0; padding: 1em; }
/* Update XHTML classes accordingly */

4. Split CSS by Usage

If analysis shows clear separation:

• typography.css - Font declarations, text styles
• layout.css - Spacing, positioning, grid
• components.css - Worksheets, quizzes, callouts
• print.css - Print-specific overrides

Example Invocation

User: "The CSS files seem large. Can you check if there's unused code?"

Agent response:

1. Run CSS coverage analyzer
2. Read docs/CSS_COVERAGE.md
3. Summarize findings:

CSS Coverage Analysis Complete
===============================

Current state:
- Total CSS: 37.1 KB (487 selectors)
- Used: 412 selectors (84.6%)
- Unused: 75 selectors (15.4%)
- Missing: 8 selectors (need definitions)

Top opportunities:
1. Remove 75 unused selectors → Save ~5.2 KB (14% reduction)
2. Consolidate 12 redundant rules → Save ~0.8 KB
3. Add 8 missing definitions for worksheet elements

Estimated optimized size: 31.9 KB (14% reduction)

Recommended actions:
1. Review unused selectors in CSS_COVERAGE.md
2. Add missing worksheet/reflection styles
3. Test visual QA after changes
4. Consider splitting into modular CSS files

Full report: docs/CSS_COVERAGE.md

Integration with Other Skills

Run after:

• epub-visual-auditor - Understand which styles are actually rendered

Run before:

• epub-publication-validator - Clean CSS before final validation
• Final packaging - Smaller CSS = faster EPUB load times

Notes

• CSS coverage is computed per XHTML file (not live browser rendering)
• Pseudo-classes (:hover, :focus) may be flagged as unused (ignore these)
• Print-specific rules may only appear when generating PDFs (keep these)
• Some selectors may be defensive (future-proofing) - use judgment before removing
• Re-run coverage after any CSS changes to verify impact