fix: handle uppercase pseudo elements

Author: alexander-akait

src/__tests__/guards.js

@@ -89,6 +89,16 @@ test('special pseudo element guard', ':before:after', (t, tree) => {
     });
 });
 
+test('special pseudo element guard (uppercase)', ':BEFORE:AFTER', (t, tree) => {
+    [node(tree), node(tree, 1)].forEach((n) => {
+        t.true(parser.isPseudo(n));
+        t.false(parser.isPseudoClass(n));
+        t.true(parser.isPseudoElement(n));
+        t.true(parser.isContainer(n));
+        t.false(parser.isNamespace(n));
+    });
+});
+
 test('string guard', '"string"', (t, tree) => {
     let n = node(tree);
     t.true(parser.isNode(n));

src/selectors/guards.js

@@ -54,8 +54,8 @@ export function isPseudoElement (node) {
            && node.value
            && (
                node.value.startsWith("::")
-             || node.value === ":before"
-             || node.value === ":after"
+             || node.value.toLowerCase() === ":before"
+             || node.value.toLowerCase() === ":after"
            );
 }
 export function isPseudoClass (node) {