tyle.transition = `transform ${transitionSpeed} ease-in-out, opacity ${transitionSpeed} ease-in-out`;
      }

      document.addEventListener("DOMContentLoaded", async () => {
        refreshButton = document.getElementById("refresh-button");
        refreshButton.addEventListener("click", handleManualRefresh);

        createParticles();
        initializeCharts();
        await fetchHeartRateData();
        startLiveTimestamp();
        startCountdown();

        setInterval(fetchHeartRateData, 60000);
 