<button id="pwaBtn" style="display:none; background:#00d2ff; color:white; padding:15px 25px; border-radius:12px; border:none; font-weight:bold; cursor:pointer; font-family:sans-serif; box-shadow: 0 4px 10px rgba(0,0,0,0.1);">
   INSTALAR APP
</button>

<script>
    if("serviceWorker" in navigator){ navigator.serviceWorker.register("sw.js"); }
    let link = document.createElement("link"); 
    link.rel = "manifest"; 
    link.href = "manifest.json"; 
    document.head.appendChild(link);
    
    let deferredPrompt;
    window.addEventListener("beforeinstallprompt", (e) => {
        e.preventDefault(); 
        deferredPrompt = e;
        document.getElementById("pwaBtn").style.display = "block";
    });

    document.getElementById("pwaBtn").addEventListener("click", async () => {
        if(deferredPrompt){
            deferredPrompt.prompt();
            const { outcome } = await deferredPrompt.userChoice;
            if(outcome === "accepted") deferredPrompt = null;
        }
    });
</script>