Escape is not preserved in class selector

[tophf]

To reproduce:

.dark\:bg-gray-800 {
     display: none;
}

Current behavior:

No \ in the compiled code.

Expected behavior:

\ should be preserved in the compiled code.

Environment information:

• stylus version: using https://stylus-lang.com/try.html
• nodejs version: same

1. There's an inconvenient workaround {'.dark\:bg-gray-800'} or simply .dark\\:bg-gray-800
2. https://stylus-lang.com/try.html needs a fix to preserve the escapes in pasted text:

--- a/docs/.vitepress/components/Runkit.vue
+++ b/docs/.vitepress/components/Runkit.vue
@@ -8,7 +8,7 @@
   const RUNKIT_ID = 'runkit-id';
   const CODE = `
   const stylus = require("stylus"); 
-  const str = \`
+  const str = String.raw\`
   // your stylus code here
   body
     color white