diff --git a/index.html b/index.html
index 8add3b0..bcbf4b2 100644
--- a/index.html
+++ b/index.html
@@ -49,6 +49,13 @@
       </header>
 
       <main>
+        <!-- Install prompt -->
+        <div class="install-banner" id="install-banner">
+          <span class="install-banner-icon">📲</span>
+          <span id="install-banner-text"></span>
+          <button class="install-banner-close" id="install-banner-close" aria-label="Dismiss">✕</button>
+        </div>
+
         <!-- Emoji picker -->
         <div class="emoji-section">
           <div
@@ -244,6 +251,33 @@
             </div>
           </div>
 
+          <div class="field">
+            <label>Display Mastodon option</label>
+            <div
+              class="theme-toggle"
+              id="mastodon-vis-toggle"
+              role="group"
+              aria-label="Show or hide the Mastodon option"
+            >
+              <button
+                class="theme-btn"
+                data-mastodon-vis="show"
+                type="button"
+                aria-pressed="true"
+              >
+                Show
+              </button>
+              <button
+                class="theme-btn"
+                data-mastodon-vis="hide"
+                type="button"
+                aria-pressed="false"
+              >
+                Hide
+              </button>
+            </div>
+          </div>
+
           <div class="field">
             <label>Appearance</label>
             <div
diff --git a/script.js b/script.js
index 7431cd4..044e8ad 100644
--- a/script.js
+++ b/script.js
@@ -1,6 +1,6 @@
 // ── State ────────────────────────────────────────────────────────────────────
 let emoji = "💬";
-let settings = { username: "", apiKey: "", theme: "auto", mastodonPost: false };
+let settings = { username: "", apiKey: "", theme: "auto", mastodonPost: false, showMastodon: true };
 
 // ── DOM ──────────────────────────────────────────────────────────────────────
 const $ = (id) => document.getElementById(id);
@@ -20,7 +20,9 @@ const sApikey = $("s-apikey");
 const eyeBtn = $("eye-btn");
 const saveBtn = $("save-btn");
 const themeToggle = $("theme-toggle");
+const mastodonVisToggle = $("mastodon-vis-toggle");
 const mastodonToggle = $("mastodon-toggle");
+const mastodonRow = mastodonToggle.closest(".field");
 
 // ── Settings ─────────────────────────────────────────────────────────────────
 function applyTheme(theme) {
@@ -44,12 +46,25 @@ function updateThemeToggle(theme) {
   });
 }
 
+function applyMastodonVisibility(show) {
+  mastodonRow.style.display = show ? "" : "none";
+}
+
+function updateMastodonVisToggle(show) {
+  mastodonVisToggle.querySelectorAll(".theme-btn").forEach((btn) => {
+    const active = (btn.dataset.mastodonVis === "show") === show;
+    btn.classList.toggle("active", active);
+    btn.setAttribute("aria-pressed", active ? "true" : "false");
+  });
+}
+
 function loadSettings() {
   try {
     const raw = localStorage.getItem("spo-settings");
     if (raw) settings = { ...settings, ...JSON.parse(raw) };
   } catch {}
   applyTheme(settings.theme);
+  applyMastodonVisibility(settings.showMastodon ?? true);
   updateBadge();
   mastodonToggle.checked = settings.mastodonPost ?? false;
 }
@@ -80,6 +95,7 @@ function openModal() {
   sUsername.value = settings.username;
   sApikey.value = settings.apiKey;
   updateThemeToggle(settings.theme);
+  updateMastodonVisToggle(settings.showMastodon ?? true);
   overlay.classList.add("open");
   document.body.style.overflow = "hidden";
   // Focus first empty field
@@ -121,6 +137,15 @@ mastodonToggle.addEventListener("change", () => {
   try { localStorage.setItem("spo-settings", JSON.stringify(settings)); } catch {}
 });
 
+mastodonVisToggle.addEventListener("click", (e) => {
+  const btn = e.target.closest(".theme-btn");
+  if (!btn) return;
+  const show = btn.dataset.mastodonVis === "show";
+  settings.showMastodon = show;
+  applyMastodonVisibility(show);
+  updateMastodonVisToggle(show);
+});
+
 themeToggle.addEventListener("click", (e) => {
   const btn = e.target.closest(".theme-btn");
   if (!btn) return;
@@ -280,6 +305,36 @@ if ("serviceWorker" in navigator) {
   navigator.serviceWorker.register("sw.js").catch(() => {});
 }
 
+// ── Install banner ────────────────────────────────────────────────────────────
+(function () {
+  const isPWA =
+    window.matchMedia("(display-mode: standalone)").matches ||
+    navigator.standalone === true;
+  if (isPWA) return;
+
+  try {
+    if (localStorage.getItem("spo-install-dismissed")) return;
+  } catch {}
+
+  const ua = navigator.userAgent;
+  let msg = null;
+  if (/iPad|iPhone|iPod/.test(ua)) {
+    msg = 'Tap Share ↑ at the bottom of Safari, then "Add to Home Screen" to install this app.';
+  } else if (/Android/.test(ua)) {
+    msg = 'Tap the ⋮ menu in Chrome, then "Add to Home Screen" to install this app.';
+  }
+  if (!msg) return;
+
+  const banner = $("install-banner");
+  $("install-banner-text").textContent = msg;
+  banner.classList.add("visible");
+
+  $("install-banner-close").addEventListener("click", () => {
+    banner.classList.remove("visible");
+    try { localStorage.setItem("spo-install-dismissed", "1"); } catch {}
+  });
+})();
+
 // ── Init ──────────────────────────────────────────────────────────────────────
 loadSettings();
 
diff --git a/style.css b/style.css
index 66d9e33..d644ea4 100644
--- a/style.css
+++ b/style.css
@@ -608,6 +608,43 @@ input::placeholder {
   opacity: 0.8;
 }
 
+/* ── Install banner ────────────────────────────────────────────────────── */
+.install-banner {
+  display: none;
+  gap: 10px;
+  align-items: flex-start;
+  background: var(--accent-dim);
+  border: 1.5px solid color-mix(in srgb, var(--accent) 30%, transparent);
+  border-radius: var(--r);
+  padding: 12px 14px;
+  font-size: 0.875rem;
+  color: var(--text);
+  line-height: 1.5;
+}
+
+.install-banner.visible {
+  display: flex;
+}
+
+.install-banner-icon {
+  font-size: 1.1rem;
+  flex-shrink: 0;
+  margin-top: 1px;
+}
+
+.install-banner-close {
+  background: none;
+  border: none;
+  cursor: pointer;
+  color: var(--muted);
+  font-size: 0.8rem;
+  padding: 2px 0 0;
+  margin-left: auto;
+  flex-shrink: 0;
+  line-height: 1;
+  -webkit-tap-highlight-color: transparent;
+}
+
 /* ── Theme segmented control ───────────────────────────────────────────── */
 .theme-toggle {
   display: flex;