fix: characters escaping (#4472)

src/language-css/printer-postcss.js

@@ -410,9 +410,6 @@ function genericPrint(path, options, print) {
         const iNextNode = node.groups[i + 1];
         const iNextNextNode = node.groups[i + 2];
 
-        if (isPostcssSimpleVar(iNode, iNextNode)) {
-          continue;
-        }
         // Ignore after latest node (i.e. before semicolon)
         if (!iNextNode) {
           continue;
@@ -433,6 +430,16 @@ function genericPrint(path, options, print) {
           continue;
         }
 
+        // Ignore `\` (i.e. `$variable: \@small;`)
+        if (iNode.value === "\\") {
+          continue;
+        }
+
+        // Ignore `$$` (i.e. `background-color: $$(style)Color;`)
+        if (isPostcssSimpleVar(iNode, iNextNode)) {
+          continue;
+        }
+
         if (
           (iPrevNode &&
             iPrevNode.type === "value-comment" &&