Resolve helper functions in CSS previews (#766)

packages/tailwindcss-language-server/src/server.ts

@@ -767,6 +767,13 @@ async function createProjectService(
                   .default
             ),
           },
+          evaluateTailwindFunctions: {
+            module: firstOptional(
+              () =>
+                require(resolveFrom(configDir, 'tailwindcss/lib/lib/evaluateTailwindFunctions'))
+                  .default
+            ),
+          },
         }
       } catch (_) {
         try {

packages/tailwindcss-language-service/src/util/jit.ts

@@ -18,6 +18,7 @@ export function generateRules(
 
   let root = state.modules.postcss.module.root({ nodes: rules.map(([, rule]) => rule) })
   state.modules.jit.expandApplyAtRules.module(state.jitContext)(root)
+  state.modules.jit.evaluateTailwindFunctions?.module?.(state.jitContext)(root)
 
   let actualRules: Rule[] = []
   root.walkRules((subRule) => {

packages/tailwindcss-language-service/src/util/state.ts

@@ -110,6 +110,7 @@ export interface State {
       generateRules: { module: any }
       createContext: { module: any }
       expandApplyAtRules: { module: any }
+      evaluateTailwindFunctions?: { module: any }
     }
   }
   browserslist?: string[]