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Fix 0px being converted to unitless 0 and breaking calc calculations #121

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Fix 0px being converted to unitless 0 and breaking calc calculations #121

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bcdcf79
Fix 0px being converted to unitless 0 or 0rem
claude May 25, 2026
87123f3
Use --* propList pattern in 0px custom property regression test
claude May 25, 2026
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39 changes: 23 additions & 16 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,12 +6,18 @@ const defaults = {
rootValue: 16,
unitPrecision: 5,
selectorBlackList: [],
propList: ["font", "font-size", "line-height", "letter-spacing", "word-spacing"],
propList: [
"font",
"font-size",
"line-height",
"letter-spacing",
"word-spacing"
],
replace: true,
mediaQuery: false,
minPixelValue: 0,
exclude: null,
unit: "px",
unit: "px"
};

const legacyOptions = {
Expand All @@ -20,7 +26,7 @@ const legacyOptions = {
selector_black_list: "selectorBlackList",
prop_white_list: "propList",
media_query: "mediaQuery",
propWhiteList: "propList",
propWhiteList: "propList"
};

function convertLegacyOptions(options) {
Expand All @@ -36,7 +42,7 @@ function convertLegacyOptions(options) {
delete options["prop_white_list"];
delete options.propWhiteList;
}
Object.keys(legacyOptions).forEach((key) => {
Object.keys(legacyOptions).forEach(key => {
if (Reflect.has(options, key)) {
options[legacyOptions[key]] = options[key];
delete options[key];
Expand All @@ -48,6 +54,7 @@ function createPxReplace(rootValue, unitPrecision, minPixelValue) {
return (m, $1) => {
if (!$1) return m;
const pixels = parseFloat($1);
if (pixels === 0) return m;
if (pixels < minPixelValue) return m;
const fixedVal = toFixed(pixels / rootValue, unitPrecision);
return fixedVal + "rem";
Expand All @@ -61,12 +68,12 @@ function toFixed(number, precision) {
}

function declarationExists(decls, prop, value) {
return decls.some((decl) => decl.prop === prop && decl.value === value);
return decls.some(decl => decl.prop === prop && decl.value === value);
}

function blacklistedSelector(blacklist, selector) {
if (typeof selector !== "string") return;
return blacklist.some((regex) => {
return blacklist.some(regex => {
if (typeof regex === "string") {
return selector.indexOf(regex) !== -1;
}
Expand All @@ -85,31 +92,31 @@ function createPropListMatcher(propList) {
notExact: filterPropList.notExact(propList),
notContain: filterPropList.notContain(propList),
notStartWith: filterPropList.notStartWith(propList),
notEndWith: filterPropList.notEndWith(propList),
notEndWith: filterPropList.notEndWith(propList)
};
return (prop) => {
return prop => {
if (matchAll) return true;
return (
(hasWild ||
lists.exact.indexOf(prop) > -1 ||
lists.contain.some(function (m) {
lists.contain.some(function(m) {
return prop.indexOf(m) > -1;
}) ||
lists.startWith.some(function (m) {
lists.startWith.some(function(m) {
return prop.indexOf(m) === 0;
}) ||
lists.endWith.some(function (m) {
lists.endWith.some(function(m) {
return prop.indexOf(m) === prop.length - m.length;
})) &&
!(
lists.notExact.indexOf(prop) > -1 ||
lists.notContain.some(function (m) {
lists.notContain.some(function(m) {
return prop.indexOf(m) > -1;
}) ||
lists.notStartWith.some(function (m) {
lists.notStartWith.some(function(m) {
return prop.indexOf(m) === 0;
}) ||
lists.notEndWith.some(function (m) {
lists.notEndWith.some(function(m) {
return prop.indexOf(m) === prop.length - m.length;
})
)
Expand Down Expand Up @@ -146,7 +153,7 @@ module.exports = (options = {}) => {
pxReplace = createPxReplace(
rootValue,
opts.unitPrecision,
opts.minPixelValue,
opts.minPixelValue
);
},
Declaration(decl) {
Expand Down Expand Up @@ -177,7 +184,7 @@ module.exports = (options = {}) => {
if (atRule.params.indexOf(opts.unit) === -1) return;
atRule.params = atRule.params.replace(pxRegex(opts.unit), pxReplace);
}
},
}
};
};
module.exports.postcss = true;
9 changes: 9 additions & 0 deletions spec/pxtorem-spec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,15 @@ describe("pxtorem", function() {

expect(processed).toBe(expected);
});

it("should not convert 0px to unitless 0 for CSS custom properties", function() {
var input = ":root { --tw-ring-offset-width: 0px; }";
var expected = ":root { --tw-ring-offset-width: 0px; }";
var options = { propList: ["--*"] };
var processed = postcss(pxtorem(options)).process(input).css;

expect(processed).toBe(expected);
});
});

describe("value parsing", function() {
Expand Down