diff --git a/web_app/static/index.html b/web_app/static/index.html
index 0d56371..69569a5 100644
--- a/web_app/static/index.html
+++ b/web_app/static/index.html
@@ -116,7 +116,10 @@ <h2 id="contentHeading">Lyrics</h2>
                                 </div>
                             </div>
 
-                            <button id="generateBtn" class="primary-btn">Generate Poster</button>
+                            <button id="generateBtn" class="primary-btn">
+                                <span class="btn-text">Generate Poster</span>
+                                <div class="spinner btn-spinner" style="display: none;"></div>
+                            </button>
                         </div>
                     </div>
 
diff --git a/web_app/static/script.js b/web_app/static/script.js
index 441a4ed..d2e7b10 100644
--- a/web_app/static/script.js
+++ b/web_app/static/script.js
@@ -613,7 +613,20 @@ function handleLyricLineClick(lineNumber) {
 async function generatePoster() {
     if (!currentMetadata) return;
 
-    loadingOverlay.style.display = 'flex';
+    const btn = document.getElementById('generateBtn');
+    const btnText = btn.querySelector('.btn-text');
+    const btnSpinner = btn.querySelector('.btn-spinner');
+
+    btn.disabled = true;
+    btnText.style.display = 'none';
+    btnSpinner.style.display = 'block';
+
+    const resetBtn = () => {
+        btn.disabled = false;
+        btnText.style.display = 'inline';
+        btnSpinner.style.display = 'none';
+    };
+
 
     const indexingToggle = document.getElementById('indexingToggle');
     const accentToggle = document.getElementById('accentToggle');
@@ -635,7 +648,7 @@ async function generatePoster() {
         const end = endVal;
 
         if (isNaN(start) || isNaN(end) || start >= end) {
-            loadingOverlay.style.display = 'none';
+            resetBtn();
             showToast("Please enter a valid range (Start must be less than End).", "error");
             return;
         }
@@ -669,13 +682,17 @@ async function generatePoster() {
             posterContainer.innerHTML = '';
             posterContainer.appendChild(img);
             showDownloadButton(imageUrl, data.filename);
-            loadingOverlay.style.display = 'none';
+            resetBtn();
+        };
+        img.onerror = () => {
+            showToast('Failed to load the generated poster image.', 'error');
+            resetBtn();
         };
 
     } catch (error) {
         console.error("Generation failed", error);
         showToast(`Error: ${error.message}`, "error");
-        loadingOverlay.style.display = 'none';
+        resetBtn();
     }
 }
 
diff --git a/web_app/static/style.css b/web_app/static/style.css
index 468eb76..1ef50bb 100644
--- a/web_app/static/style.css
+++ b/web_app/static/style.css
@@ -908,4 +908,21 @@ input:focus {
 
 .result-action svg {
     pointer-events: none;
-}
\ No newline at end of file
+}
+.primary-btn:disabled {
+    background-color: var(--accent-hover);
+    opacity: 0.7;
+    cursor: not-allowed;
+    transform: none;
+}
+
+.btn-spinner {
+    width: 20px;
+    height: 20px;
+    border-width: 2px;
+    border-top-color: #1a1a1f; /* Match button text color */
+    border-right-color: rgba(26, 26, 31, 0.2);
+    border-bottom-color: rgba(26, 26, 31, 0.2);
+    border-left-color: rgba(26, 26, 31, 0.2);
+    margin: 0; /* Override margin from .spinner */
+}