diff --git a/packages/sdk/src/engine/model.ts b/packages/sdk/src/engine/model.ts
index 6c61b9e41..58a0cb361 100644
--- a/packages/sdk/src/engine/model.ts
+++ b/packages/sdk/src/engine/model.ts
@@ -138,16 +138,42 @@ function toKebab(prop: string): string {
 }
 
 /** Parse style attribute string → camelCase map (custom props kept as-is). */
+// fallow-ignore-next-line complexity
 function parseStyleAttr(styleAttr: string): Record<string, string> {
   const result: Record<string, string> = {};
-  for (const decl of styleAttr.split(";")) {
+  const flush = (decl: string): void => {
     const idx = decl.indexOf(":");
-    if (idx === -1) continue;
+    if (idx === -1) return;
     const rawProp = decl.slice(0, idx).trim();
     const value = decl.slice(idx + 1).trim();
-    if (!rawProp || !value) continue;
+    if (!rawProp || !value) return;
     result[toCamel(rawProp)] = value;
+  };
+  // Split on ';' only when outside quotes and balanced parens, so a value that
+  // carries a semicolon survives intact: data URIs, url(), and quoted strings
+  // (`url("data:image/svg+xml;base64,…")`, `content: "a;b"`). A naive
+  // split(";") truncates those. Mirrors the same-package class-style tokenizer
+  // (cssWriter.ts parseDeclarations) and the server patchStyleAttrString path.
+  let depth = 0;
+  let quote: string | null = null;
+  let start = 0;
+  for (let i = 0; i < styleAttr.length; i++) {
+    const ch = styleAttr[i]!;
+    if (quote) {
+      if (ch === "\\") i++; // skip escaped char
+      else if (ch === quote) quote = null;
+      continue;
+    }
+    if (ch === '"' || ch === "'") quote = ch;
+    else if (ch === "(") depth++;
+    else if (ch === ")") depth = Math.max(0, depth - 1);
+    else if (ch === ";" && depth === 0) {
+      flush(styleAttr.slice(start, i));
+      start = i + 1;
+    }
   }
+  // Trailing declaration; also recovers the tail if a quote was left unterminated.
+  flush(styleAttr.slice(start));
   return result;
 }
 
diff --git a/packages/sdk/src/engine/mutate.test.ts b/packages/sdk/src/engine/mutate.test.ts
index 4334787c4..c89f06359 100644
--- a/packages/sdk/src/engine/mutate.test.ts
+++ b/packages/sdk/src/engine/mutate.test.ts
@@ -324,14 +324,14 @@ describe("removeElement", () => {
 
 // ─── setElementStyles (model helper) ──────────────────────────────────────────
 
-describe("setElementStyles key normalization", () => {
-  function elWith(style: string): Element {
-    const parsed = parseMutable(`<div data-hf-id="hf-x" data-hf-root style="${style}"></div>`);
-    const el = parsed.document.querySelector('[data-hf-id="hf-x"]');
-    if (!el) throw new Error("fixture element missing");
-    return el;
-  }
+function elWith(style: string): Element {
+  const parsed = parseMutable(`<div data-hf-id="hf-x" data-hf-root style="${style}"></div>`);
+  const el = parsed.document.querySelector('[data-hf-id="hf-x"]');
+  if (!el) throw new Error("fixture element missing");
+  return el;
+}
 
+describe("setElementStyles key normalization", () => {
   it("removes a hyphenated property when value is null", () => {
     const el = elWith("transform-origin: center center; opacity: 0.5");
     setElementStyles(el, { "transform-origin": null });
@@ -366,6 +366,41 @@ describe("setElementStyles key normalization", () => {
   });
 });
 
+describe("setElementStyles preserves semicolons inside values", () => {
+  it("keeps a data-URI value intact when editing a sibling property", () => {
+    // A naive split(";") truncates the url() at the ';' inside the data URI,
+    // dropping the background when an unrelated property is edited. Mirrors the
+    // class-style coverage in mutate.cssstyle.test.ts.
+    const el = elWith(
+      "background: url(data:image/svg+xml;base64,PHN2Zz09) no-repeat; opacity: 0.5",
+    );
+    setElementStyles(el, { opacity: "1" });
+    const styles = getElementStyles(el);
+    expect(styles.background).toBe("url(data:image/svg+xml;base64,PHN2Zz09) no-repeat");
+    expect(styles.opacity).toBe("1");
+    expect(el.getAttribute("style")).toContain("base64,PHN2Zz09");
+  });
+
+  it("keeps a quoted value containing a semicolon intact", () => {
+    const el = elWith("content: 'a;b'; opacity: 0.5");
+    setElementStyles(el, { opacity: "1" });
+    const styles = getElementStyles(el);
+    expect(styles.content).toBe("'a;b'");
+    expect(styles.opacity).toBe("1");
+  });
+
+  it("removes a semicolon-bearing property cleanly", () => {
+    const el = elWith(
+      "background: url(data:image/svg+xml;base64,PHN2Zz09); opacity: 0.5",
+    );
+    setElementStyles(el, { background: null });
+    const styles = getElementStyles(el);
+    expect(styles.background).toBeUndefined();
+    expect(styles.opacity).toBe("0.5");
+    expect(el.getAttribute("style")).toBe("opacity: 0.5");
+  });
+});
+
 // ─── setVariableValue ─────────────────────────────────────────────────────────
 
 describe("setVariableValue", () => {