Merge branch 'main' into next

# Conflicts:
#	package.json
#	scripts/release/yarn.lock
#	src/language-css/parser-postcss.js
#	src/language-css/printer-postcss.js
#	src/language-js/print/jsx.js
#	src/language-json/printer-estree-json.js
#	website/yarn.lock
#	yarn.lock

src/language-css/parser-postcss.js

@@ -544,13 +544,21 @@ async function parseNestedCSS(node, options) {
           node.params?.[0] === ":"
         ) {
           node.variable = true;
-          node.value = await parseValue(node.params.slice(1), options);
+          const text = node.params.slice(1);
+          if (text) {
+            node.value = await parseValue(text, options);
+          }
           node.raws.afterName += ":";
         }
 
         // Less variable
         if (node.variable) {
           delete node.params;
+
+          if (!node.value) {
+            delete node.value;
+          }
+
           return node;
         }
       }