🚀

Author: vslinko

index.js

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+const postcss = require('postcss')
+const crypto = require('crypto')
+
+const declPatterns = [
+	/(margin|padding)-(left|right|top|bottom)/,
+	/font-size/,
+]
+
+function updateDecl(decl) {
+	const hash = parseInt(crypto.createHash('sha1').update(JSON.stringify(decl)).digest('hex'), 16)
+	const matches = /^(\d+)([a-z]+)$/i.exec(decl.value)
+
+	if (!matches) return
+
+	const diff = hash % 5
+
+	decl.replaceWith(decl.clone({
+		value: `${Number(matches[1]) + diff}${matches[2]}`
+	}))
+}
+
+module.exports = postcss.plugin('postcss-pixel-imperfect', (opts) => (css) => {
+	declPatterns.forEach((declPattern) => {
+		css.walkDecls(declPattern, updateDecl)
+	})
+})

package.json

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+{
+  "name": "postcss-pixel-imperfect",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "node test.js"
+  },
+  "author": "Viacheslav Slinko <vslinko@yahoo.com>",
+  "license": "MIT",
+  "devDependencies": {
+    "postcss": "^5.0.21",
+    "tape": "^4.6.0"
+  }
+}

test.js

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+const test = require('tape')
+const postcss = require('postcss')
+const plugin = require('./index')
+
+function run(t, input, output, opts = {}) {
+	return postcss([ plugin(opts) ])
+		.process(input)
+    .then( result => {
+      t.deepEqual(result.css, output)
+      t.deepEqual(result.warnings().length, 0)
+			t.end()
+    })
+}
+
+test('some', (t) => {
+	run(t, `
+		.header {
+			font-size: 1pt;
+			margin-top: 10px;
+			margin-bottom: 10px;
+		}
+	`, `
+		.header {
+			font-size: 4pt;
+			margin-top: 10px;
+			margin-bottom: 13px;
+		}
+	`)
+})