diff --git a/static/js/chart_controls.js b/static/js/chart_controls.js
index 47e6135..771ba8f 100644
--- a/static/js/chart_controls.js
+++ b/static/js/chart_controls.js
@@ -68,7 +68,7 @@ document.addEventListener("DOMContentLoaded", function () {
             this.textContent = "Przełącz na kategorie";
             window.setCategorySplit(false);
         } else {
-            this.classList.add("outline-light");
+            this.classList.add("btn-outline-light");
             this.classList.remove("btn-outline-light");
             this.setAttribute("aria-pressed", "true");
             this.textContent = "Przełącz na sumy";