diff --git a/admin.html b/admin.html
index b5c0d2f..d1f59f6 100644
--- a/admin.html
+++ b/admin.html
@@ -455,11 +455,45 @@
     // ===========================
     // IMAGE UPLOAD
     // ===========================
+    async function resizeImage(file, maxPx = 1920, quality = 0.85) {
+      if (file.type === 'image/gif') return file;
+      return new Promise(resolve => {
+        const img = new Image();
+        const url = URL.createObjectURL(file);
+        img.onload = () => {
+          URL.revokeObjectURL(url);
+          const ratio = Math.min(maxPx / img.naturalWidth, maxPx / img.naturalHeight, 1);
+          if (ratio === 1 && file.size < 1.5 * 1024 * 1024) { resolve(file); return; }
+          const canvas = document.createElement('canvas');
+          canvas.width  = Math.round(img.naturalWidth  * ratio);
+          canvas.height = Math.round(img.naturalHeight * ratio);
+          canvas.getContext('2d').drawImage(img, 0, 0, canvas.width, canvas.height);
+          canvas.toBlob(
+            blob => resolve(new File([blob], 'image.jpg', { type: 'image/jpeg' })),
+            'image/jpeg', quality
+          );
+        };
+        img.src = url;
+      });
+    }
+
     async function uploadImgAdmin(input, hiddenId, previewId, labelId) {
       const file = input.files[0];
       if (!file) return;
+
+      const allowed = ['image/jpeg', 'image/png', 'image/gif', 'image/webp'];
+      if (!allowed.includes(file.type)) {
+        showToast('⚠️ Tuetut muodot: JPG, PNG, GIF, WebP');
+        input.value = '';
+        return;
+      }
+
+      const lbl = document.getElementById(labelId);
+      lbl.style.opacity = '0.5';
+
+      const resized = await resizeImage(file);
       const formData = new FormData();
-      formData.append('file', file);
+      formData.append('file', resized, resized.name || 'image.jpg');
       try {
         const res = await fetch('upload.php', { method: 'POST', body: formData });
         if (!res.ok) throw new Error(await res.text());
@@ -468,9 +502,11 @@
         const prev = document.getElementById(previewId);
         prev.src = data.url;
         prev.style.display = 'block';
-        document.getElementById(labelId).classList.add('has-image');
+        lbl.classList.add('has-image');
       } catch (e) {
-        showToast('⚠️ Kuvan lataus epäonnistui.');
+        showToast('⚠️ Kuvan lataus epäonnistui. Tuetut muodot: JPG, PNG, GIF, WebP.');
+      } finally {
+        lbl.style.opacity = '';
       }
     }
 
diff --git a/script.js b/script.js
index e090bc3..0699293 100644
--- a/script.js
+++ b/script.js
@@ -389,11 +389,47 @@ function closeSubmitModal() {
   document.body.style.overflow = '';
 }
 
+async function resizeImage(file, maxPx = 1920, quality = 0.85) {
+  // Älä muuta GIF:ejä (animaatio menisi rikki)
+  if (file.type === 'image/gif') return file;
+  return new Promise(resolve => {
+    const img = new Image();
+    const url = URL.createObjectURL(file);
+    img.onload = () => {
+      URL.revokeObjectURL(url);
+      const ratio = Math.min(maxPx / img.naturalWidth, maxPx / img.naturalHeight, 1);
+      // Jos kuva on jo tarpeeksi pieni, palauta sellaisenaan
+      if (ratio === 1 && file.size < 1.5 * 1024 * 1024) { resolve(file); return; }
+      const canvas = document.createElement('canvas');
+      canvas.width  = Math.round(img.naturalWidth  * ratio);
+      canvas.height = Math.round(img.naturalHeight * ratio);
+      canvas.getContext('2d').drawImage(img, 0, 0, canvas.width, canvas.height);
+      canvas.toBlob(
+        blob => resolve(new File([blob], 'image.jpg', { type: 'image/jpeg' })),
+        'image/jpeg', quality
+      );
+    };
+    img.src = url;
+  });
+}
+
 async function uploadImg(input, hiddenId, previewId, labelId) {
   const file = input.files[0];
   if (!file) return;
+
+  const allowed = ['image/jpeg', 'image/png', 'image/gif', 'image/webp'];
+  if (!allowed.includes(file.type)) {
+    alert('Tuetut kuvamuodot: JPG, PNG, GIF, WebP');
+    input.value = '';
+    return;
+  }
+
+  const lbl = document.getElementById(labelId);
+  lbl.style.opacity = '0.5';
+
+  const resized = await resizeImage(file);
   const formData = new FormData();
-  formData.append('file', file);
+  formData.append('file', resized, resized.name || 'image.jpg');
   try {
     const res = await fetch('upload.php', { method: 'POST', body: formData });
     if (!res.ok) throw new Error(await res.text());
@@ -402,9 +438,11 @@ async function uploadImg(input, hiddenId, previewId, labelId) {
     const prev = document.getElementById(previewId);
     prev.src = data.url;
     prev.style.display = 'block';
-    document.getElementById(labelId).classList.add('has-image');
+    lbl.classList.add('has-image');
   } catch (e) {
-    alert('Kuvan lataus epäonnistui: ' + e.message);
+    alert('Kuvan lataus epäonnistui. Tuetut muodot: JPG, PNG, GIF, WebP (max 8 MB).');
+  } finally {
+    lbl.style.opacity = '';
   }
 }