diff --git a/packages/next-yak/loaders/__tests__/classifier.test.ts b/packages/next-yak/loaders/__tests__/classifier.test.ts
new file mode 100644
index 00000000..49a060de
--- /dev/null
+++ b/packages/next-yak/loaders/__tests__/classifier.test.ts
@@ -0,0 +1,133 @@
+import quasiClassifier from '../lib/quasiClassifier.cjs';
+import { describe, it, expect } from "vitest";
+
+describe('quasiClassifier', () => {
+    it('should classify empty quasi', () => {
+        expect(quasiClassifier('', [])).toEqual({
+            empty: true,
+            unknownSelector: false,
+            insideCssValue: false,
+            currentNestingScopes: [],
+        });
+    });
+    it("should recognize a comment as empty", () => {
+        expect(quasiClassifier("/* comment */", [])).toEqual({
+            empty: true,
+            unknownSelector: false,
+            insideCssValue: false,
+            currentNestingScopes: [],
+        });
+    });
+    it("should find incomplete css - unknownSelector", () => {
+        expect(quasiClassifier("{ color: blue;", [])).toEqual({
+            empty: false,
+            unknownSelector: true,
+            insideCssValue: false,
+            currentNestingScopes: [],
+        });
+    });
+    it("should find incomplete css - insideCssValue", () => {
+        expect(quasiClassifier("color: ", [
+            ".foo"
+        ])).toEqual({
+            empty: false,
+            unknownSelector: false,
+            insideCssValue: true,
+            currentNestingScopes: [".foo"],
+        });
+    });
+    it("should find incomplete css - insideCssValue after a media query", () => {
+        expect(quasiClassifier("} .foo { color: ", [
+            "@media (min-width: 640px)"
+        ])).toEqual({
+            empty: false,
+            unknownSelector: false,
+            insideCssValue: true,
+            currentNestingScopes: [".foo"],
+        });
+    });
+    it("should find incomplete css - insideCssValue in a multi value", () => {
+        expect(quasiClassifier("} .foo { transition: 200ms ", [
+            "@media (min-width: 640px)"
+        ])).toEqual({
+            empty: false,
+            unknownSelector: false,
+            insideCssValue: true,
+            currentNestingScopes: [".foo"],
+        });
+    });
+    it("should find nesting scopes", () => {
+        expect(quasiClassifier(`
+            .foo {
+                .bar {
+                    @supports (display: grid) {
+        `, [
+            "@media (min-width: 640px)"
+        ])).toEqual({
+            empty: false,
+            unknownSelector: false,
+            insideCssValue: false,
+            currentNestingScopes: [
+                "@media (min-width: 640px)",
+                ".foo",
+                ".bar",
+                "@supports (display: grid)",
+            ],
+        });
+    });
+    it("should find nesting scopes with properties", () => {
+        expect(quasiClassifier(`
+            .foo {
+                color: purple;
+                .x {
+                    color: green;
+                }
+                .bar {
+                    color: orange;
+                    @supports (display: grid) {
+                        color: blue;
+        `, [
+            "@media (min-width: 640px)"
+        ])).toEqual({
+            empty: false,
+            unknownSelector: false,
+            insideCssValue: false,
+            currentNestingScopes: [
+                "@media (min-width: 640px)",
+                ".foo",
+                ".bar",
+                "@supports (display: grid)",
+            ],
+        });
+    });
+
+    it("should find nesting scopes with properties and closing nestings", () => {
+        expect(quasiClassifier(`
+            .foo {
+                /* }}}}} */
+                color: purple;
+                .x {
+                    color: green;
+                }
+                .bar {
+                    :before {
+                        content: '{';
+                    }
+                    color: orange;
+                    @supports (display: grid) {
+                        color: blue;
+                    }
+                }
+        `, [
+            "@media (min-width: 640px)"
+        ])).toEqual({
+            empty: false,
+            unknownSelector: false,
+            insideCssValue: false,
+            currentNestingScopes: [
+                "@media (min-width: 640px)",
+                ".foo",
+            ],
+        });
+    });
+});
diff --git a/packages/next-yak/loaders/__tests__/tsloader.test.ts b/packages/next-yak/loaders/__tests__/tsloader.test.ts
index ee214473..0a9adb61 100644
--- a/packages/next-yak/loaders/__tests__/tsloader.test.ts
+++ b/packages/next-yak/loaders/__tests__/tsloader.test.ts
@@ -166,13 +166,12 @@ const FancyButton = styled(Button)\`
       const FancyButton = styled(Button)(__styleYak.FancyButton_2);"
     `);
   });
-});
 
-it("should support attrs on intrinsic elements", async () => {
-  expect(
-    await tsloader.call(
-      loaderContext,
-      `
+  it("should support attrs on intrinsic elements", async () => {
+    expect(
+      await tsloader.call(
+        loaderContext,
+        `
 import { styled } from "next-yak";
 
 const headline = styled.input.attrs({
@@ -181,21 +180,21 @@ const headline = styled.input.attrs({
   color: red;
   \`;
 `
-    )
-  ).toMatchInlineSnapshot(`
+      )
+    ).toMatchInlineSnapshot(`
     "import { styled } from \\"next-yak\\";
     import __styleYak from \\"./page.yak.module.css!=!./page?./page.yak.module.css\\";
     const headline = styled.input.attrs({
       type: \\"text\\"
     })(__styleYak.headline_0);"
   `);
-});
+  });
 
-it("should support attrs on wrapped elements", async () => {
-  expect(
-    await tsloader.call(
-      loaderContext,
-      `
+  it("should support attrs on wrapped elements", async () => {
+    expect(
+      await tsloader.call(
+        loaderContext,
+        `
 import { styled } from "next-yak";
 
 const headline = styled.input\`
@@ -208,8 +207,8 @@ const newHeadline = styled(headline).attrs({
   color: black;
   \`;
 `
-    )
-  ).toMatchInlineSnapshot(`
+      )
+    ).toMatchInlineSnapshot(`
     "import { styled } from \\"next-yak\\";
     import __styleYak from \\"./page.yak.module.css!=!./page?./page.yak.module.css\\";
     const headline = styled.input(__styleYak.headline_0);
@@ -217,13 +216,13 @@ const newHeadline = styled(headline).attrs({
       type: \\"text\\"
     })(__styleYak.newHeadline_1);"
   `);
-});
+  });
 
-it("should support css variables with spaces", async () => {
-  expect(
-    await tsloader.call(
-      loaderContext,
-      `
+  it("should support css variables with spaces", async () => {
+    expect(
+      await tsloader.call(
+        loaderContext,
+        `
 import styles from "./page.module.css";
 import { css } from "next-yak";
 import { easing } from "styleguide";
@@ -235,8 +234,8 @@ const headline = css\`
   \${css\`color: blue\`}
   \`;
 `
-    )
-  ).toMatchInlineSnapshot(`
+      )
+    ).toMatchInlineSnapshot(`
     "import styles from \\"./page.module.css\\";
     import { css } from \\"next-yak\\";
     import __styleYak from \\"./page.yak.module.css!=!./page?./page.yak.module.css\\";
@@ -250,13 +249,13 @@ const headline = css\`
       }
     });"
   `);
-});
+  });
 
-it("should convert keyframes", async () => {
-  expect(
-    await tsloader.call(
-      loaderContext,
-      `
+  it("should convert keyframes", async () => {
+    expect(
+      await tsloader.call(
+        loaderContext,
+        `
 import styles from "./page.module.css";
 import { styled, keyframes } from "next-yak";
 
@@ -273,8 +272,8 @@ const FadeInButton = styled.button\`
   animation: 1s \${fadeIn} ease-out;
 \`
 `
-    )
-  ).toMatchInlineSnapshot(`
+      )
+    ).toMatchInlineSnapshot(`
   "import styles from \\"./page.module.css\\";
   import { styled, keyframes } from \\"next-yak\\";
   import __styleYak from \\"./page.yak.module.css!=!./page?./page.yak.module.css\\";
@@ -285,13 +284,13 @@ const FadeInButton = styled.button\`
     }
   });"
 `);
-});
+  });
 
-it("should allow to target components", async () => {
-  expect(
-    await tsloader.call(
-      loaderContext,
-      `
+  it("should allow to target components", async () => {
+    expect(
+      await tsloader.call(
+        loaderContext,
+        `
 import { styled, keyframes } from "next-yak";
 
 const Link = styled.a\`
@@ -317,21 +316,21 @@ const Wrapper = styled.div\`
 \`
 
 `
-    )
-  ).toMatchInlineSnapshot(`
+      )
+    ).toMatchInlineSnapshot(`
     "import { styled, keyframes } from \\"next-yak\\";
     import __styleYak from \\"./page.yak.module.css!=!./page?./page.yak.module.css\\";
     const Link = styled.a(__styleYak.Link_0);
     const Icon = styled.svg(__styleYak.Icon_1);
     const Wrapper = styled.div(__styleYak.Wrapper_2);"
   `);
-});
+  });
 
-it("should allow to target components even if they don't have styles", async () => {
-  expect(
-    await tsloader.call(
-      loaderContext,
-      `
+  it("should allow to target components even if they don't have styles", async () => {
+    expect(
+      await tsloader.call(
+        loaderContext,
+        `
 import { styled, keyframes } from "next-yak";
 
 const Link = styled.a\`
@@ -347,12 +346,65 @@ const Wrapper = styled.div\`
 \`
 
 `
-    )
-  ).toMatchInlineSnapshot(`
+      )
+    ).toMatchInlineSnapshot(`
     "import { styled, keyframes } from \\"next-yak\\";
     import __styleYak from \\"./page.yak.module.css!=!./page?./page.yak.module.css\\";
     const Link = styled.a();
     const Icon = styled.svg(__styleYak.Icon_1);
     const Wrapper = styled.div(__styleYak.Wrapper_2);"
   `);
+  });
+
+  it("should show error when mixin is used in nested selector", async () => {
+    await expect(() =>
+      tsloader.call(
+        loaderContext,
+        `
+import { styled, css } from "next-yak";
+
+const bold = css\`
+  font-weight: bold;
+\`
+
+const Icon = styled.div\`
+  @media (min-width: 640px) {
+    .bar {
+      \${bold}
+    }
+  }
+\`
+`
+      )
+    ).rejects.toThrowErrorMatchingInlineSnapshot(`
+    "/some/special/path/page.tsx: Expressions are not allowed inside nested selectors:
+    line 11: found \\"bold\\" inside \\"@media (min-width: 640px) { .bar {\\""
+  `);
+  });
+
+  it("should show error when mixin is used in nested selector inside a css", async () => {
+    await expect(() =>
+      tsloader.call(
+        loaderContext,
+        `
+import { styled, css } from "next-yak";
+
+const bold = css\`
+  font-weight: bold;
+\`
+
+const Icon = styled.div\`
+  @media (min-width: 640px) {
+    .bar {
+      \${() => css\`\${bold}\`}
+    }
+  }
+\`
+`
+      )
+    ).rejects.toThrowErrorMatchingInlineSnapshot(`
+    "/some/special/path/page.tsx: Expressions are not allowed inside nested selectors:
+    line 11: found Expression inside \\"@media (min-width: 640px) { .bar {\\""
+  `);
+  });
 });
diff --git a/packages/next-yak/loaders/babel-yak-plugin.cjs b/packages/next-yak/loaders/babel-yak-plugin.cjs
index 059f8051..70464cef 100644
--- a/packages/next-yak/loaders/babel-yak-plugin.cjs
+++ b/packages/next-yak/loaders/babel-yak-plugin.cjs
@@ -62,9 +62,9 @@ module.exports = function (babel, options) {
           t.importDeclaration(
             [t.importDefaultSpecifier(t.identifier("__styleYak"))],
             t.stringLiteral(
-              `./${fileName}.yak.module.css!=!./${fileName}?./${fileName}.yak.module.css`
-            )
-          )
+              `./${fileName}.yak.module.css!=!./${fileName}?./${fileName}.yak.module.css`,
+            ),
+          ),
         );
 
         // Process import specifiers
@@ -115,7 +115,7 @@ module.exports = function (babel, options) {
         const isStyledLiteral =
           t.isMemberExpression(tag) &&
           t.isIdentifier(
-            /** @type {babel.types.MemberExpression} */ (tag).object
+            /** @type {babel.types.MemberExpression} */ (tag).object,
           ) &&
           /** @type {babel.types.Identifier} */ (
             /** @type {babel.types.MemberExpression} */ (tag).object
@@ -123,7 +123,7 @@ module.exports = function (babel, options) {
         const isStyledCall =
           t.isCallExpression(tag) &&
           t.isIdentifier(
-            /** @type {babel.types.CallExpression} */ (tag).callee
+            /** @type {babel.types.CallExpression} */ (tag).callee,
           ) &&
           /** @type {babel.types.Identifier} */ (
             /** @type {babel.types.CallExpression} */ (tag).callee
@@ -169,15 +169,15 @@ module.exports = function (babel, options) {
                 astNode.arguments.push(
                   t.memberExpression(
                     t.identifier("__styleYak"),
-                    t.identifier(className)
-                  )
+                    t.identifier(className),
+                  ),
                 );
               }
               return className;
             }
             return false;
           },
-          t
+          t,
         );
 
         let literalSelectorWasUsed = false;
@@ -189,17 +189,21 @@ module.exports = function (babel, options) {
             localIdent(
               variableName,
               literalSelectorIndex,
-              isKeyframesLiteral ? "animation" : "className"
-            )
-          )
+              isKeyframesLiteral ? "animation" : "className",
+            ),
+          ),
         );
 
         // Replace the tagged template expression with a call to the 'styled' function
         const newArguments = new Set();
         const quasis = path.node.quasi.quasis;
-        const quasiTypes = quasis.map((quasi) =>
-          quasiClassifier(quasi.value.raw)
-        );
+        /** @type {string[]} */
+        let currentNestingScopes = [];
+        const quasiTypes = quasis.map((quasi) => {
+          const classification = quasiClassifier(quasi.value.raw, currentNestingScopes);
+          currentNestingScopes = classification.currentNestingScopes;
+          return classification;
+        });
         const expressions = path.node.quasi.expressions;
 
         let cssVariablesInlineStyle;
@@ -226,8 +230,8 @@ module.exports = function (babel, options) {
             const type = quasiTypes[i];
             // expressions after a partial css are converted into css variables
             if (
-              type.partialStart ||
-              type.partialEnd ||
+              type.unknownSelector ||
+              type.insideCssValue ||
               (isMerging && type.empty)
             ) {
               isMerging = true;
@@ -249,7 +253,7 @@ module.exports = function (babel, options) {
                 }
                 const relativePath = relative(
                   rootContext,
-                  resolve(rootContext, resourcePath)
+                  resolve(rootContext, resourcePath),
                 );
                 hashedFile = murmurhash2_32_gc(relativePath);
               }
@@ -257,14 +261,23 @@ module.exports = function (babel, options) {
               cssVariablesInlineStyle.properties.push(
                 t.objectProperty(
                   t.stringLiteral(`--🦬${hashedFile}${this.varIndex++}`),
-                  /** @type {babel.types.Expression} */ (expression)
-                )
+                  /** @type {babel.types.Expression} */ (expression),
+                ),
               );
             } else if (type.empty) {
-              // empty quasis can be ignored
+              // empty quasis can be ignored in typescript
               // e.g. `transition: color ${duration} ${easing};`
+              //                                    ^
             } else {
               if (expressions[i]) {
+                if (quasiTypes[i].currentNestingScopes.length > 0) {
+                  const errorExpression = expressions[i];
+                  const name = errorExpression.type === "Identifier" ? `"${errorExpression.name}"` : "Expression";
+                  const line = errorExpression.loc?.start.line || -1
+                  throw new InvalidPositionError(
+                    `Expressions are not allowed inside nested selectors:\n${line !== -1 ? `line ${line}: ` : ""}found ${name} inside "${quasiTypes[i].currentNestingScopes.join(" { ")} {"`,
+                  );
+                }
                 newArguments.add(expressions[i]);
               }
               break;
@@ -277,9 +290,9 @@ module.exports = function (babel, options) {
             t.objectExpression([
               t.objectProperty(
                 t.stringLiteral(`style`),
-                cssVariablesInlineStyle
+                cssVariablesInlineStyle,
               ),
-            ])
+            ]),
           );
         }
 
@@ -294,7 +307,7 @@ module.exports = function (babel, options) {
             className: localIdent(
               variableName,
               literalSelectorIndex,
-              "className"
+              "className",
             ),
             astNode: styledCall,
           });
@@ -303,3 +316,14 @@ module.exports = function (babel, options) {
     },
   };
 };
+
+class InvalidPositionError extends Error {
+  /**
+   * @param {string} message
+   */
+  constructor(message) {
+    super(message);
+  }
+}
+
+module.exports.InvalidPositionError = InvalidPositionError;
\ No newline at end of file
diff --git a/packages/next-yak/loaders/cssloader.cjs b/packages/next-yak/loaders/cssloader.cjs
index cf2e8557..2236cfb9 100644
--- a/packages/next-yak/loaders/cssloader.cjs
+++ b/packages/next-yak/loaders/cssloader.cjs
@@ -34,7 +34,7 @@ module.exports = async function cssLoader(source) {
       imports.forEach(({ localName, importedName }) => {
         replaces[localName] = constantValues[importedName];
       });
-    })
+    }),
   );
 
   // parse source with babel
@@ -127,7 +127,7 @@ module.exports = async function cssLoader(source) {
       const isStyledLiteral =
         t.isMemberExpression(tag) &&
         t.isIdentifier(
-          /** @type {babel.types.MemberExpression} */ (tag).object
+          /** @type {babel.types.MemberExpression} */ (tag).object,
         ) &&
         /** @type {babel.types.Identifier} */ (
           /** @type {babel.types.MemberExpression} */ (tag).object
@@ -136,7 +136,7 @@ module.exports = async function cssLoader(source) {
       const isStyledCall =
         t.isCallExpression(tag) &&
         t.isIdentifier(
-          /** @type {babel.types.CallExpression} */ (tag).callee
+          /** @type {babel.types.CallExpression} */ (tag).callee,
         ) &&
         /** @type {babel.types.Identifier} */ (
           /** @type {babel.types.CallExpression} */ (tag).callee
@@ -176,7 +176,7 @@ module.exports = async function cssLoader(source) {
           }
           return false;
         },
-        t
+        t,
       );
 
       // Keep the same selector for all quasis belonging to the same css block
@@ -184,14 +184,12 @@ module.exports = async function cssLoader(source) {
       const literalSelector = localIdent(
         variableName,
         literalSelectorIndex,
-        isKeyFrameLiteral ? "keyframes" : "selector"
+        isKeyFrameLiteral ? "keyframes" : "selector",
       );
 
       // Replace the tagged template expression with a call to the 'styled' function
       const quasis = path.node.quasi.quasis;
-      const quasiTypes = quasis.map((quasi) =>
-        quasiClassifier(quasi.value.raw)
-      );
+      const quasiTypes = quasis.map((quasi) => quasiClassifier(quasi.value.raw, []));
 
       for (let i = 0; i < quasis.length; i++) {
         const quasi = quasis[i];
@@ -206,8 +204,8 @@ module.exports = async function cssLoader(source) {
           const type = quasiTypes[i];
           // expressions after a partial css are converted into css variables
           if (
-            type.partialStart ||
-            type.partialEnd ||
+            type.unknownSelector ||
+            type.insideCssValue ||
             (isMerging && type.empty)
           ) {
             isMerging = true;
@@ -243,7 +241,7 @@ module.exports = async function cssLoader(source) {
       if (isStyledLiteral || isStyledCall || isAttrsCall) {
         variableNameToStyledClassName.set(
           variableName,
-          localIdent(variableName, literalSelectorIndex, "selector")
+          localIdent(variableName, literalSelectorIndex, "selector"),
         );
       }
     },
diff --git a/packages/next-yak/loaders/lib/getStyledComponentName.cjs b/packages/next-yak/loaders/lib/getStyledComponentName.cjs
index fcb60683..19478b1c 100644
--- a/packages/next-yak/loaders/lib/getStyledComponentName.cjs
+++ b/packages/next-yak/loaders/lib/getStyledComponentName.cjs
@@ -13,7 +13,7 @@
  */
 const getStyledComponentName = (taggedTemplateExpressionPath) => {
   const variableDeclaratorPath = taggedTemplateExpressionPath.findParent(
-    (path) => path.isVariableDeclarator()
+    (path) => path.isVariableDeclarator(),
   );
   if (
     !variableDeclaratorPath ||
@@ -22,7 +22,7 @@ const getStyledComponentName = (taggedTemplateExpressionPath) => {
   ) {
     throw new Error(
       "Could not find variable declaration for styled component at " +
-        taggedTemplateExpressionPath.node.loc
+        taggedTemplateExpressionPath.node.loc,
     );
   }
   return variableDeclaratorPath.node.id.name;
diff --git a/packages/next-yak/loaders/lib/getYakImports.cjs b/packages/next-yak/loaders/lib/getYakImports.cjs
index 0028f28b..ca4813d1 100644
--- a/packages/next-yak/loaders/lib/getYakImports.cjs
+++ b/packages/next-yak/loaders/lib/getYakImports.cjs
@@ -1,38 +1,47 @@
 // @ts-check
 /**
  * Finds all imports in a given code string which import from a .yak file
- * 
+ *
  * Uses regex to work with typescript and javascript
  * Does not support lazy imports
- * 
+ *
  * @param {string} code
  * @returns { { imports: { localName: string, importedName: string }[], from: string }[] }
  */
 const getYakImports = (code) => {
-    const codeWithoutComments = code.replace(/\/\*[\s\S]*?\*\//g, '');
-    const allImports = codeWithoutComments.matchAll(/(^|\n|;)\s*import\s+(?:(\w+(?:\s+as\s+\w+)?)\s*,?\s*)?(?:{([^}]*)})?\s+from\s+["']([^'"]+\.yak)["'](;|\n)/g);
-    return [...allImports].map(([, , defaultImport, namedImports, from,]) => {
-        // parse named imports to { localName: string, importedName: string }[]
-        const imports = namedImports?.split(',').map((namedImport) => {
-            const [importedName, localName = importedName] = namedImport.replace(/^type\s+/, "").trim().split(/\s+as\s+/);
-            return { localName, importedName };
-        }) ?? [];
-        // parse default import to { localName: string, importedName: string }[]
-        if (defaultImport) {
-            imports.push(parseDefaultImport(defaultImport));
-        }
-        return { imports, from };
-    });
+  const codeWithoutComments = code.replace(/\/\*[\s\S]*?\*\//g, "");
+  const allImports = codeWithoutComments.matchAll(
+    /(^|\n|;)\s*import\s+(?:(\w+(?:\s+as\s+\w+)?)\s*,?\s*)?(?:{([^}]*)})?\s+from\s+["']([^'"]+\.yak)["'](;|\n)/g,
+  );
+  return [...allImports].map(([, , defaultImport, namedImports, from]) => {
+    // parse named imports to { localName: string, importedName: string }[]
+    const imports =
+      namedImports?.split(",").map((namedImport) => {
+        const [importedName, localName = importedName] = namedImport
+          .replace(/^type\s+/, "")
+          .trim()
+          .split(/\s+as\s+/);
+        return { localName, importedName };
+      }) ?? [];
+    // parse default import to { localName: string, importedName: string }[]
+    if (defaultImport) {
+      imports.push(parseDefaultImport(defaultImport));
+    }
+    return { imports, from };
+  });
 };
 
 /**
  * Parses a default import string
  * @param {string} defaultImport
  * @returns {{ localName: string, importedName: string }}
- */   
+ */
 function parseDefaultImport(defaultImport) {
-    const defaultImportArray = defaultImport.split(/\s+as\s+/);
-    return { localName: defaultImportArray[1] ?? defaultImportArray[0], importedName: defaultImportArray[0] }
+  const defaultImportArray = defaultImport.split(/\s+as\s+/);
+  return {
+    localName: defaultImportArray[1] ?? defaultImportArray[0],
+    importedName: defaultImportArray[0],
+  };
 }
 
-module.exports = getYakImports;
\ No newline at end of file
+module.exports = getYakImports;
diff --git a/packages/next-yak/loaders/lib/quasiClassifier.cjs b/packages/next-yak/loaders/lib/quasiClassifier.cjs
index 14bda58c..6462666f 100644
--- a/packages/next-yak/loaders/lib/quasiClassifier.cjs
+++ b/packages/next-yak/loaders/lib/quasiClassifier.cjs
@@ -3,31 +3,85 @@ const stripCssComments = require("./stripCssComments.cjs");
 
 /**
  * Checks a quasiValue and returns its type
- * 
+ *
  * - empty: no expressions, no text
- * - partialStart: starts with a `{`
- * - partialEnd: does not end with a `}` or `;`
- * 
- * @param {string} quasiValue 
+ * - unknownSelector: starts with a `{` e.g. `{ opacity: 0.5; }`
+ * - insideCssValue: does not end with a `{` or `}` or `;` e.g. `color: `
+ *
+ * @param {string} quasiValue
+ * @param {string[]} currentNestingScopes - the current nesting scope
+ *
  * @returns {{
  *  empty: boolean,
- *  partialStart: boolean,
- *  partialEnd: boolean,
+ *  unknownSelector: boolean,
+ *  insideCssValue: boolean,
+ *  currentNestingScopes: string[],
  * }}
  */
-module.exports = function quasiClassifier(quasiValue) {
-    const trimmed = stripCssComments(quasiValue).trim();
-    if (trimmed === "") {
-        return {
-            empty: true,
-            partialStart: false,
-            partialEnd: false,
-        }
-    }
-
+module.exports = function quasiClassifier(quasiValue, currentNestingScopes) {
+  // TODO - for better performance we could move the comment skipping logic
+  // directly in the for loop below instead of calling stripCssComments
+  const trimmedCssString = stripCssComments(quasiValue).trim();
+  if (trimmedCssString === "") {
     return {
-        empty: false,
-        partialStart: trimmed.startsWith("{"),
-        partialEnd: !trimmed.endsWith("}") && !trimmed.endsWith(";"),
+      empty: true,
+      unknownSelector: false,
+      insideCssValue: false,
+      currentNestingScopes,
+    };
+  }
+  /** @type {'"' | "'" | false} */
+  let isInsideString = false;
+  let currentCharacter = "";
+  let newNestingLevel = [...currentNestingScopes];
+  let currentSelector = "";
+  for (let index = 0; index < trimmedCssString.length; index++) {
+    currentCharacter = trimmedCssString[index];
+    if (
+      trimmedCssString[index - 1] !== "\\" &&
+      (currentCharacter === '"' || currentCharacter === "'")
+    ) {
+      if (isInsideString === currentCharacter) {
+        isInsideString = false;
+      } else if (!isInsideString) {
+        isInsideString = currentCharacter;
+      }
+    }
+    if (isInsideString) {
+      continue;
     }
-}
\ No newline at end of file
+    if (currentCharacter === "{") {
+      const selector = currentSelector.trim();
+      if (selector !== "") {
+        newNestingLevel.push(selector);
+      }
+      // after an opening bracket a new selector might start e.g.:
+      // .class {
+      //   .nested-class {
+      currentSelector = "";
+    } else if (currentCharacter === "}") {
+      newNestingLevel.pop();
+      // after a closing bracket a new selector might start e.g.:
+      // .class {
+      //   color: red;
+      // }
+      // .other-class {
+      currentSelector = "";
+    } else if (currentCharacter === ";") {
+      // after a semi-colon a nested selector might start e.g.:
+      // .class {
+      //   color: red;
+      //   .nested-class {
+      currentSelector = "";
+    } else {
+      currentSelector += currentCharacter;
+    }
+  }
+
+  return {
+    empty: false,
+    unknownSelector: trimmedCssString[0] === "{",
+    insideCssValue: currentCharacter !== "{" && currentCharacter !== "}" && currentCharacter !== ";",
+    currentNestingScopes: newNestingLevel,
+  };
+};
diff --git a/packages/next-yak/loaders/lib/replaceQuasiExpressionTokens.cjs b/packages/next-yak/loaders/lib/replaceQuasiExpressionTokens.cjs
index 9388026c..3bc58998 100644
--- a/packages/next-yak/loaders/lib/replaceQuasiExpressionTokens.cjs
+++ b/packages/next-yak/loaders/lib/replaceQuasiExpressionTokens.cjs
@@ -35,10 +35,13 @@ module.exports = function replaceTokensInQuasiExpressions(quasi, replacer, t) {
       }
       replaceExpressionAndMergeQuasis(quasi, i, replacement);
       i--;
-    } 
+    }
     // replace member expressions e.g. ${query.xs}
     // replace deeply nested member expressions e.g. ${query.xs.min}
-    else if (t.isMemberExpression(expression) && t.isIdentifier(expression.object)) {
+    else if (
+      t.isMemberExpression(expression) &&
+      t.isIdentifier(expression.object)
+    ) {
       /** @type {any} */
       let replacement = replacer(expression.object.name);
       if (replacement === false) {
@@ -60,7 +63,7 @@ module.exports = function replaceTokensInQuasiExpressions(quasi, replacer, t) {
       i--;
     }
   }
-}
+};
 
 /**
  * Replace tokens with predefined values
@@ -69,9 +72,16 @@ module.exports = function replaceTokensInQuasiExpressions(quasi, replacer, t) {
  * @param {unknown} replacement
  */
 function replaceExpressionAndMergeQuasis(quasi, expressionIndex, replacement) {
-  const stringReplacement = typeof replacement === "string" ? replacement : replacement == null ? "" : JSON.stringify(replacement);
+  const stringReplacement =
+    typeof replacement === "string"
+      ? replacement
+      : replacement == null
+      ? ""
+      : JSON.stringify(replacement);
   quasi.expressions.splice(expressionIndex, 1);
-  quasi.quasis[expressionIndex].value.raw += stringReplacement + quasi.quasis[expressionIndex + 1].value.raw;
-  quasi.quasis[expressionIndex].value.cooked += stringReplacement + quasi.quasis[expressionIndex + 1].value.cooked;
+  quasi.quasis[expressionIndex].value.raw +=
+    stringReplacement + quasi.quasis[expressionIndex + 1].value.raw;
+  quasi.quasis[expressionIndex].value.cooked +=
+    stringReplacement + quasi.quasis[expressionIndex + 1].value.cooked;
   quasi.quasis.splice(expressionIndex + 1, 1);
-}
\ No newline at end of file
+}
diff --git a/packages/next-yak/loaders/lib/stripCssComments.cjs b/packages/next-yak/loaders/lib/stripCssComments.cjs
index cfc7b016..4898ce9b 100644
--- a/packages/next-yak/loaders/lib/stripCssComments.cjs
+++ b/packages/next-yak/loaders/lib/stripCssComments.cjs
@@ -1,51 +1,58 @@
 /// @ts-check
 // from https://github.com/sindresorhus/strip-css-comments/tree/main
 /**
- * 
- * @param {string} cssString 
+ *
+ * @param {string} cssString
  */
 module.exports = function stripCssComments(cssString) {
-	/** @type {string | false} */
-	let isInsideString = false;
-	let currentCharacter = '';
-	let comment = '';
-	let returnValue = '';
+  /** @type {string | false} */
+  let isInsideString = false;
+  let currentCharacter = "";
+  let comment = "";
+  let returnValue = "";
 
-	for (let index = 0; index < cssString.length; index++) {
-		currentCharacter = cssString[index];
+  for (let index = 0; index < cssString.length; index++) {
+    currentCharacter = cssString[index];
 
-		if (cssString[index - 1] !== '\\' && (currentCharacter === '"' || currentCharacter === '\'')) {
-			if (isInsideString === currentCharacter) {
-				isInsideString = false;
-			} else if (!isInsideString) {
-				isInsideString = currentCharacter;
-			}
-		}
+    if (
+      cssString[index - 1] !== "\\" &&
+      (currentCharacter === '"' || currentCharacter === "'")
+    ) {
+      if (isInsideString === currentCharacter) {
+        isInsideString = false;
+      } else if (!isInsideString) {
+        isInsideString = currentCharacter;
+      }
+    }
 
-		// Find beginning of `/*` type comment
-		if (!isInsideString && currentCharacter === '/' && cssString[index + 1] === '*') {
-			let index2 = index + 2;
+    // Find beginning of `/*` type comment
+    if (
+      !isInsideString &&
+      currentCharacter === "/" &&
+      cssString[index + 1] === "*"
+    ) {
+      let index2 = index + 2;
 
-			// Iterate over comment
-			for (; index2 < cssString.length; index2++) {
-				// Find end of comment
-				if (cssString[index2] === '*' && cssString[index2 + 1] === '/') {
-                    if (cssString[index2 + 2] === '\n') {
-                        index2++;
-                    } else if (cssString[index2 + 2] + cssString[index2 + 3] === '\r\n') {
-                        index2 += 2;
-                    }
-					comment = '';
-					break;
-				}
-				// Store comment text
-				comment += cssString[index2];
-			}
-			// Resume iteration over CSS string from the end of the comment
-			index = index2 + 1;
-			continue;
-		}
-		returnValue += currentCharacter;
-	}
-	return returnValue;
-}
\ No newline at end of file
+      // Iterate over comment
+      for (; index2 < cssString.length; index2++) {
+        // Find end of comment
+        if (cssString[index2] === "*" && cssString[index2 + 1] === "/") {
+          if (cssString[index2 + 2] === "\n") {
+            index2++;
+          } else if (cssString[index2 + 2] + cssString[index2 + 3] === "\r\n") {
+            index2 += 2;
+          }
+          comment = "";
+          break;
+        }
+        // Store comment text
+        comment += cssString[index2];
+      }
+      // Resume iteration over CSS string from the end of the comment
+      index = index2 + 1;
+      continue;
+    }
+    returnValue += currentCharacter;
+  }
+  return returnValue;
+};
diff --git a/packages/next-yak/loaders/tsloader.cjs b/packages/next-yak/loaders/tsloader.cjs
index 83fcd862..45482ba7 100644
--- a/packages/next-yak/loaders/tsloader.cjs
+++ b/packages/next-yak/loaders/tsloader.cjs
@@ -1,6 +1,7 @@
 /// @ts-check
 const babel = require("@babel/core");
 const getYakImports = require("./lib/getYakImports.cjs");
+const InvalidPositionError = require("./babel-yak-plugin.cjs").InvalidPositionError;
 
 /**
  * Loader for typescript files that use yak, it replaces the css template literal with a call to the 'styled' function
@@ -20,34 +21,49 @@ module.exports = async function tsloader(source) {
   const isYakFile = /\.yak\.(j|t)sx?$/.test(resourcePath.matches);
   // The user may import constants from a .yak file
   // e.g. import { primary } from './colors.yak'
-  // 
+  //
   // However .yak files inside .yak files are not be compiled
   // to avoid performance overhead
-  const importedYakConstantNames = isYakFile ? [] : getYakImports(source).map(({ imports }) => imports.map(({ localName }) => localName)).flat(2);
-  const replaces = Object.fromEntries(importedYakConstantNames.map((name) => [name, null]));
+  const importedYakConstantNames = isYakFile
+    ? []
+    : getYakImports(source)
+        .map(({ imports }) => imports.map(({ localName }) => localName))
+        .flat(2);
+  const replaces = Object.fromEntries(
+    importedYakConstantNames.map((name) => [name, null])
+  );
 
-  // Compile the typescript file with babel - this will:
-  // - inject the import to the css-module (with .yak.module.css extension)
-  // - replace the css template literal with styles from the css-module
-  const result = babel.transformSync(source, {
-    filename: resourcePath,
-    configFile: false,
-    plugins: [
-      [
-        "@babel/plugin-syntax-typescript",
-        { isTSX: this.resourcePath.endsWith(".tsx") },
+  /** @type {babel.BabelFileResult | null} */
+  let result = null;
+  try {
+    // Compile the typescript file with babel - this will:
+    // - inject the import to the css-module (with .yak.module.css extension)
+    // - replace the css template literal with styles from the css-module
+    result = babel.transformSync(source, {
+      filename: resourcePath,
+      configFile: false,
+      plugins: [
+        [
+          "@babel/plugin-syntax-typescript",
+          { isTSX: this.resourcePath.endsWith(".tsx") },
+        ],
+        [
+          require.resolve("./babel-yak-plugin.cjs"),
+          {
+            replaces,
+            rootContext,
+          },
+        ],
       ],
-      [
-        require.resolve("./babel-yak-plugin.cjs"),
-        {
-          replaces,
-          rootContext,
-        },
-      ],
-    ],
-  });
+    });
+  } catch (error) {
+    if (error instanceof InvalidPositionError) {
+      return callback(new Error(error.message));
+    }
+    return callback(new Error("babel transform failed"));
+  }
   if (!result?.code) {
-    throw new Error("babel transform failed");
+    return callback(new Error("babel transform failed"));
   }
   return callback(null, result.code, result.map);
 };
diff --git a/packages/next-yak/package.json b/packages/next-yak/package.json
index 76fd1040..0803df6a 100644
--- a/packages/next-yak/package.json
+++ b/packages/next-yak/package.json
@@ -1,6 +1,6 @@
 {
   "name": "next-yak",
-  "version": "0.0.18",
+  "version": "0.0.19",
   "type": "module",
   "types": "./dist/",
   "exports": {