I think this will fix types?

src/css.ts

@@ -1,5 +1,7 @@
 import {keyframes, StyleRule} from '@vanilla-extract/css'
 import {compile} from 'stylis'
+import {QwikStyledComponent} from './qwik-styled'
+import {ClassNames} from './ve-style'
 
 export const veClassRE = /^[a-zA-Z0-9_./]*[a-z0-9]{6}\d+$/
 export const veMultiClassRE = /^([a-zA-Z0-9_./]*[a-z0-9]{6}\d+( |$)){2,}/
@@ -22,7 +24,7 @@ const changeAnimName = (rule: StyleRule, name: string, real: string) => {
 }
 export const css = (
 	tpl: TemplateStringsArray,
-	...expr: string[]
+	...expr: (StyleRule | QwikStyledComponent | ClassNames)[]
 ): StyleRule => {
 	let output = tpl[0]
 	for (let i = 1; i < tpl.length; i++) {

src/qwik-styled.ts

@@ -122,7 +122,7 @@ export type Tags =
 
 export type QwikStyledComponent<Tag extends Tags = 'div'> = FunctionComponent<
 	QwikIntrinsicElements[Tag]
-> & {class: string} & string
+> & {class: string}
 
 export const isStyled = (o: any): o is QwikStyledComponent =>
 	typeof o === 'function' && 'class' in o