diff --git a/app.py b/app.py
index 78a749a..6d45723 100644
--- a/app.py
+++ b/app.py
@@ -12,6 +12,41 @@ from datetime import datetime
 from flask import Flask, render_template, request, jsonify, redirect, url_for, send_file
 from fpdf import FPDF
 
+def image_dimensions(filepath):
+    """Liest Pixelmasse aus PNG/JPEG/WebP ohne externe Libs."""  # noqa: E501
+    with open(filepath, 'rb') as f:
+        head = f.read(24)
+    if head[:8] == b'\x89PNG\r\n\x1a\n':
+        import struct
+        return struct.unpack('>II', head[16:24])
+    if head[:2] == b'\xff\xd8':
+        import struct
+        with open(filepath, 'rb') as f:
+            data = f.read(8192)
+        i = 2
+        while i < len(data) - 1:
+            if data[i] != 0xFF:
+                i += 1
+                continue
+            marker = data[i+1]
+            if marker in (0xC0, 0xC1, 0xC2):
+                h, w = struct.unpack('>HH', data[i+5:i+9])
+                return w, h
+            length = struct.unpack('>H', data[i+2:i+4])[0]
+            i += 2 + length
+    if head[:4] == b'RIFF' and head[8:12] == b'WEBP':
+        import struct
+        with open(filepath, 'rb') as f:
+            data = f.read(64)
+        if data[12:16] == b'VP8 ' and len(data) >= 30:
+            w, h = struct.unpack('<HH', data[26:30])
+            return (w & 0x3FFF) * 2, (h & 0x3FFF) * 2
+        if data[12:16] == b'VP8L' and len(data) >= 25:
+            bits = struct.unpack('<I', data[21:25])[0]
+            return (bits & 0x3FFF) + 1, ((bits >> 14) & 0x3FFF) + 1
+    return None, None
+
+
 app = Flask(__name__)
 app.config['MAX_CONTENT_LENGTH'] = 5 * 1024 * 1024
 CONFIG_FILE = 'druckkalkulation_config.yaml'
@@ -256,8 +291,12 @@ def invoice_pdf():
     logo_name = config.get('logo', '')
     logo_path = os.path.join('static', logo_name) if logo_name else ''
     if logo_name and os.path.exists(logo_path):
-        pdf.image(logo_path, x=155, y=8, w=40)
-        logo_bottom = 50
+        pdf.image(logo_path, x=155, y=5, w=40)
+        img_w, img_h = image_dimensions(logo_path)
+        if img_w and img_h:
+            logo_bottom = 5 + 40 * (img_h / img_w) + 3
+        else:
+            logo_bottom = 5 + 25 + 3
     else:
         pdf.set_font("Arial", "B", 18)
         pdf.set_xy(150, 15)