Fixed issue with negative classes not being generated when used with a prefix.

src/lib/generateRules.js

@@ -140,9 +140,11 @@ function* resolveMatchedPlugins(classCandidate, context) {
   let candidatePrefix = classCandidate
   let negative = false
 
-  if (candidatePrefix[0] === '-') {
+  const twConfigPrefix = context.tailwindConfig.prefix || ''
+  const twConfigPrefixLen = twConfigPrefix.length
+  if (candidatePrefix[twConfigPrefixLen] === '-') {
     negative = true
-    candidatePrefix = candidatePrefix.slice(1)
+    candidatePrefix = twConfigPrefix + candidatePrefix.slice(twConfigPrefixLen + 1)
   }
 
   for (let [prefix, modifier] of candidatePermutations(candidatePrefix)) {

tests/05-prefix.test.css

@@ -47,6 +47,9 @@
 .tw-dark .tw-group:hover .custom-component {
   font-weight: 400;
 }
+.tw--ml-4 {
+  margin-left: -1rem;
+}
 .tw-font-bold {
   font-weight: 700;
 }
@@ -71,6 +74,12 @@
   text-align: left;
 }
 @media (min-width: 768px) {
+  .md\:tw--ml-5 {
+    margin-left: -1.25rem;
+  }
+  .md\:hover\:tw--ml-6:hover {
+    margin-left: -1.5rem;
+  }
   .md\:hover\:tw-text-right:hover {
     text-align: right;
   }

tests/05-prefix.test.html

@@ -1,3 +1,6 @@
+<div class="tw--ml-4"></div>
+<div class="md:tw--ml-5"></div>
+<div class="md:hover:tw--ml-6"></div>
 <div class="tw-container"></div>
 <div class="btn-no-prefix"></div>
 <div class="tw-btn-prefix"></div>