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sibling/padding-consistency

Status: active

Default severity: info

What it checks

The rule groups nodes by their parent dom_order and, within each group of two or more siblings, checks the four padding longhands (padding-top, padding-right, padding-bottom, padding-left) independently. For each property, it computes the median value among siblings that have a parseable pixel value for that property. Any sibling whose value deviates from the median by more than 4 CSS pixels fires a violation.

The rule MUST skip:

  • sibling groups smaller than 2 (nothing to compare);
  • siblings where the property value does not parse as a pixel length.

Even-count medians pick the lower of the two middle values, matching the tie-break used by sibling/height-consistency.

Why it matters

Card grids, nav bars, and list items that share a parent but disagree on padding look sloppy. The 4px threshold catches real mismatches (12px vs 24px) while ignoring subpixel rendering differences. The fix is emitted at confidence: low because Plumb cannot know whether to change the outlier or update the siblings.

Example violation

{
  "rule_id": "sibling/padding-consistency",
  "severity": "info",
  "message": "`html > body > div.cards > div:nth-child(3)` has padding-top 28px; sibling median is 16px (12px drift).",
  "selector": "html > body > div.cards > div:nth-child(3)",
  "viewport": "desktop",
  "dom_order": 5,
  "fix": {
    "kind": {
      "kind": "description",
      "text": "Match sibling padding-top (16px) to keep padding consistent. Drift: 12px."
    },
    "description": "Bring `html > body > div.cards > div:nth-child(3)` padding-top in line with its siblings (16px).",
    "confidence": "low"
  },
  "doc_url": "https://plumb.aramhammoudeh.com/rules/sibling-padding-consistency",
  "metadata": {
    "property": "padding-top",
    "rendered_padding_px": 28.0,
    "sibling_median_px": 16.0,
    "deviation_px": 12
  }
}

Configuration

The rule has no plumb.toml knobs today. The deviation threshold (4 CSS px) is baked into the rule and pinned by a unit test.

Suppression

Disable the rule for an entire run:

[rules."sibling/padding-consistency"]
enabled = false

Bump or lower the severity:

[rules."sibling/padding-consistency"]
severity = "warning"

See also