diff --git a/src/index.js b/src/index.js
index 7cc2bf6..0304360 100644
--- a/src/index.js
+++ b/src/index.js
@@ -17,6 +17,7 @@ const viewportUnitRe = /^([+-]?[0-9.]+)(vh|vw|vmin|vmax)$/;
 const percentRe = /^([+-]?(?:\d*\.)?\d+(?:[Ee][+-]?\d+)?%)$/;
 const unsupportedUnitRe = /^([+-]?(?:\d*\.)?\d+(?:[Ee][+-]?\d+)?(ch|em|ex|cm|mm|in|pc|pt))$/;
 const cssPartRe = /::?part\(([^)]+)\)/;
+const rootRe = /:root/;
 const shorthandBorderProps = [
   "border-radius",
   "border-width",
@@ -100,16 +101,20 @@ const transform = (css, options) => {
       }
 
       if (
-        rule.selectors[s].indexOf(".") !== 0 ||
-        (rule.selectors[s].indexOf(":") !== -1 &&
-          (options != null && options.parsePartSelectors
-            ? !cssPartRe.test(rule.selectors[s])
-            : true)) ||
-        rule.selectors[s].indexOf("[") !== -1 ||
-        rule.selectors[s].indexOf("~") !== -1 ||
-        rule.selectors[s].indexOf(">") !== -1 ||
-        rule.selectors[s].indexOf("+") !== -1 ||
-        rule.selectors[s].indexOf(" ") !== -1
+        rootRe.test(rule.selectors[s])
+          ? false
+          : (
+            rule.selectors[s].indexOf(".") !== 0 ||
+            (rule.selectors[s].indexOf(":") !== -1 &&
+              (options != null && options.parsePartSelectors
+                ? !cssPartRe.test(rule.selectors[s])
+                : true)) ||
+            rule.selectors[s].indexOf("[") !== -1 ||
+            rule.selectors[s].indexOf("~") !== -1 ||
+            rule.selectors[s].indexOf(">") !== -1 ||
+            rule.selectors[s].indexOf("+") !== -1 ||
+            rule.selectors[s].indexOf(" ") !== -1
+          )
       ) {
         continue;
       }