diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..8f11002
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,9 @@
+.git
+.gitignore
+.dockerignore
+Dockerfile
+img/gallery/backup_orig/
+img/logo_dialysezentrum_orig.png
+files/flyer_template.html
+files/flyer_map.png
+
diff --git a/Dockerfile b/Dockerfile
index 2d8401f..d9797f2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,23 +1,24 @@
-FROM php:8.5-apache
-
-# Install common extensions (example)
-# RUN docker-php-ext-install
-
-# Enable Apache modules if needed
-RUN a2enmod rewrite
-
-# Copy application code
-COPY . /var/www/html/
-
-# Disable the legacy HTTPS redirect rules from .htaccess so the container stays on plain HTTP
-# RUN sed -i '/RewriteCond %{HTTP_HOST} !^www\\.dialyse-berlin\\.net  \[NC\]/,+2d; /RewriteCond %{HTTP_HOST} ^www\\.dialyse-berlin\\.net  \[NC\]/,+2d' /var/www/html/.htaccess || true \
-#    && a2dismod ssl || true
-
-# Set permissions
-RUN chown -R www-data:www-data /var/www/html
-
-# Optional: install Composer dependencies if you have a composer.json
-# COPY --from=composer:latest /usr/bin/composer /usr/bin/composer
-# RUN composer install --no-dev --optimize-autoloader
-
-EXPOSE 80
\ No newline at end of file
+FROM php:8.5-apache-trixie
+
+# Install system dependencies and PHP GD extension (with FreeType & JPEG/PNG support)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        libfreetype6-dev \
+        libjpeg62-turbo-dev \
+        libpng-dev \
+    && docker-php-ext-configure gd --with-freetype --with-jpeg \
+    && docker-php-ext-install -j"$(nproc)" gd \
+    && rm -rf /var/lib/apt/lists/*
+
+# Use official production php.ini and configure timezone & security settings
+RUN mv "$PHP_INI_DIR/php.ini-production" "$PHP_INI_DIR/php.ini" \
+    && printf "date.timezone = Europe/Berlin\nexpose_php = Off\nsession.cookie_httponly = 1\nsession.use_strict_mode = 1\n" > "$PHP_INI_DIR/conf.d/99-custom.ini"
+
+# Enable Apache modules and harden server signature
+RUN a2enmod rewrite headers expires deflate \
+    && printf "ServerTokens Prod\nServerSignature Off\n" > /etc/apache2/conf-available/security-hardening.conf \
+    && a2enconf security-hardening
+
+# Copy application code
+COPY --chown=www-data:www-data . /var/www/html/
+
+EXPOSE 80
\ No newline at end of file
diff --git a/captcha.php b/captcha.php
index be75678..e00ab5b 100644
--- a/captcha.php
+++ b/captcha.php
@@ -30,5 +30,4 @@ header("Pragma: no-cache");
 header("Accept-Ranges: bytes");
 header("Content-type: image/png");
 ImageTtfText($img, $ttfsize, $angle, $t_x, $t_y, $color, $ttf, $captchaText);
-ImagePNG($img);
-ImageDestroy($img);
\ No newline at end of file
+ImagePNG($img);
\ No newline at end of file