diff --git a/packages/core/src/compiler/compositionScoping.test.ts b/packages/core/src/compiler/compositionScoping.test.ts
index 7ba39a5fb..80a63c059 100644
--- a/packages/core/src/compiler/compositionScoping.test.ts
+++ b/packages/core/src/compiler/compositionScoping.test.ts
@@ -1054,4 +1054,13 @@ describe("wrapInlineScriptWithErrorBoundary — <script> breakout", () => {
     expect(body).not.toContain("</script");
     expect(scriptsAfterRoundTrip(body)).toHaveLength(1);
   });
+
+  it("drops the entire stylesheet when PostCSS cannot parse it", () => {
+    const malformedCss = `body { margin: 0; overflow: hidden; }
+:root { --accent: #5ef17c; }
+.stage { position: absolute; inset: 0; }
+.broken { transform: xPercent: -10; }`;
+    const result = scopeCssToComposition(malformedCss, "scene-bad");
+    expect(result).toBe("");
+  });
 });
diff --git a/packages/core/src/compiler/compositionScoping.ts b/packages/core/src/compiler/compositionScoping.ts
index c1fc99620..2ae8d9ee7 100644
--- a/packages/core/src/compiler/compositionScoping.ts
+++ b/packages/core/src/compiler/compositionScoping.ts
@@ -230,7 +230,12 @@ export function scopeCssToComposition(
   const scope =
     scopeSelectorOverride ||
     `[data-composition-id="${escapeCssAttributeValue(trimmedCompositionId)}"]`;
-  const root = postcss.parse(css);
+  let root: postcss.Root;
+  try {
+    root = postcss.parse(css);
+  } catch {
+    return "";
+  }
 
   root.walkRules((rule) => {
     if (isInsideGlobalAtRule(rule)) return;
diff --git a/packages/lint/src/rules/core.test.ts b/packages/lint/src/rules/core.test.ts
index b0b870d80..1bc0a21e8 100644
--- a/packages/lint/src/rules/core.test.ts
+++ b/packages/lint/src/rules/core.test.ts
@@ -777,4 +777,20 @@ describe("core rules", () => {
       expect(result.findings.find((f) => f.code === "timeline_id_mismatch")).toBeDefined();
     });
   });
+
+  describe("css_parse_error — malformed CSS is reported instead of silently swallowed", () => {
+    it("reports a css_parse_error finding for unparseable CSS", async () => {
+      const html = `<html><body>
+        <style>.stage { transform: xPercent: -10; }</style>
+        <div data-composition-id="main" data-width="1920" data-height="1080" data-start="0" data-duration="5"></div>
+        <script src="gsap.min.js"></script>
+        <script>window.__timelines = { main: gsap.timeline({ paused: true }) };</script>
+      </body></html>`;
+      const result = await lintHyperframeHtml(html);
+      const finding = result.findings.find((f) => f.code === "css_parse_error");
+      expect(finding).toBeDefined();
+      expect(finding?.severity).toBe("error");
+      expect(finding?.message).toContain("Missed semicolon");
+    });
+  });
 });
diff --git a/packages/lint/src/rules/core.ts b/packages/lint/src/rules/core.ts
index 3461a5942..8d784da2f 100644
--- a/packages/lint/src/rules/core.ts
+++ b/packages/lint/src/rules/core.ts
@@ -312,7 +312,12 @@ export const coreRules: Array<(ctx: LintContext) => HyperframeLintFinding[]> = [
       let root: postcss.Root;
       try {
         root = postcss.parse(style.content);
-      } catch {
+      } catch (error) {
+        findings.push({
+          code: "css_parse_error",
+          severity: "error",
+          message: `CSS parse error: ${error instanceof Error ? error.message : "unknown"}`,
+        });
         continue;
       }
       root.walkRules((rule) => {
