diff --git a/app.py b/app.py
index 10fa772..6720e49 100644
--- a/app.py
+++ b/app.py
@@ -1,18 +1,30 @@
 import io
 import logging
+import os
 import re
 
 import logfire
-from fastapi import FastAPI, HTTPException
+from fastapi import Depends, FastAPI, Header, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, StreamingResponse
 from pydantic import BaseModel, Field
 from weasyprint import HTML
+from weasyprint.text.fonts import FontConfiguration
 
 # Initialize logging
 logfire.configure()
 logging.basicConfig(level=logging.INFO)
 logging.basicConfig(handlers=[logfire.LogfireLoggingHandler()])
+logger = logging.getLogger("weasyprint")
+logger.handlers.clear()
+logger.setLevel(logging.DEBUG)
+logger.addHandler(logfire.LogfireLoggingHandler())
+
+# Load secret from environment variable
+SECRET_KEY = os.getenv("SECRET_KEY")
+
+if not SECRET_KEY:
+    raise RuntimeError("SECRET_KEY environment variable is not set")
 
 
 class PdfRequest(BaseModel):
@@ -66,7 +78,21 @@ async def pdf_generator(byte_string: bytes):
         chunk = byte_stream.read(4096)
 
 
-@app.post("/pdf")
+def verify_secret_key(x_secret_key: str = Header(...)):
+    """
+    Dependency to verify the secret key from the request header.
+
+    Args:
+        x_secret_key (str): The secret key from the request header.
+
+    Raises:
+        HTTPException: If the secret key is invalid.
+    """
+    if x_secret_key != SECRET_KEY:
+        raise HTTPException(status_code=401, detail="Invalid secret key")
+
+
+@app.post("/pdf", dependencies=[Depends(verify_secret_key)])
 async def pdf(body: PdfRequest):
     """
     Endpoint to convert HTML content to a PDF file.
@@ -78,8 +104,9 @@ async def pdf(body: PdfRequest):
         StreamingResponse: A streaming response with the generated PDF file.
     """
     logging.info("Received request to generate PDF")
+    font_config = FontConfiguration()
     try:
-        byte_string = HTML(string=body.html).write_pdf()
+        byte_string = HTML(string=body.html).write_pdf(font_config=font_config)
     except Exception as e:
         logging.error(f"Error generating PDF: {e}")
         raise HTTPException(status_code=400, detail="Invalid HTML input") from e
diff --git a/poetry.lock b/poetry.lock
index 3fb5f6a..6643725 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1813,32 +1813,6 @@ pygments = ">=2.13.0,<3.0.0"
 [package.extras]
 jupyter = ["ipywidgets (>=7.5.1,<9)"]
 
-[[package]]
-name = "ruff"
-version = "0.0.289"
-description = "An extremely fast Python linter, written in Rust."
-optional = false
-python-versions = ">=3.7"
-files = [
-    {file = "ruff-0.0.289-py3-none-macosx_10_7_x86_64.whl", hash = "sha256:c9a89d748e90c840bac9c37afe90cf13a5bfd460ca02ea93dad9d7bee3af03b4"},
-    {file = "ruff-0.0.289-py3-none-macosx_10_9_x86_64.macosx_11_0_arm64.macosx_10_9_universal2.whl", hash = "sha256:7f7396c6ea01ba332a6ad9d47642bac25d16bd2076aaa595b001f58b2f32ff05"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:7180de86c8ecd39624dec1699136f941c07e723201b4ce979bec9e7c67b40ad2"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:73f37c65508203dd01a539926375a10243769c20d4fcab3fa6359cd3fbfc54b7"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:1c14abcd7563b5c80be2dd809eeab20e4aa716bf849860b60a22d87ddf19eb88"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_ppc64.manylinux2014_ppc64.whl", hash = "sha256:91b6d63b6b46d4707916472c91baa87aa0592e73f62a80ff55efdf6c0668cfd6"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:6479b8c4be3c36046c6c92054762b276fa0fddb03f6b9a310fbbf4c4951267fd"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:c5424318c254bcb091cb67e140ec9b9f7122074e100b06236f252923fb41e767"},
-    {file = "ruff-0.0.289-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:4daa90865796aedcedf0d8897fdd4cd09bf0ddd3504529a4ccf211edcaff3c7d"},
-    {file = "ruff-0.0.289-py3-none-musllinux_1_2_aarch64.whl", hash = "sha256:8057e8ab0016c13b9419bad119e854f881e687bd96bc5e2d52c8baac0f278a44"},
-    {file = "ruff-0.0.289-py3-none-musllinux_1_2_armv7l.whl", hash = "sha256:7eebfab2e6a6991908ff1bf82f2dc1e5095fc7e316848e62124526837b445f4d"},
-    {file = "ruff-0.0.289-py3-none-musllinux_1_2_i686.whl", hash = "sha256:ebc7af550018001a7fb39ca22cdce20e1a0de4388ea4a007eb5c822f6188c297"},
-    {file = "ruff-0.0.289-py3-none-musllinux_1_2_x86_64.whl", hash = "sha256:6e4e6eccb753efe760ba354fc8e9f783f6bba71aa9f592756f5bd0d78db898ed"},
-    {file = "ruff-0.0.289-py3-none-win32.whl", hash = "sha256:bbb3044f931c09cf17dbe5b339896eece0d6ac10c9a86e172540fcdb1974f2b7"},
-    {file = "ruff-0.0.289-py3-none-win_amd64.whl", hash = "sha256:6d043c5456b792be2615a52f16056c3cf6c40506ce1f2d6f9d3083cfcb9eeab6"},
-    {file = "ruff-0.0.289-py3-none-win_arm64.whl", hash = "sha256:04a720bcca5e987426bb14ad8b9c6f55e259ea774da1cbeafe71569744cfd20a"},
-    {file = "ruff-0.0.289.tar.gz", hash = "sha256:2513f853b0fc42f0339b7ab0d2751b63ce7a50a0032d2689b54b2931b3b866d7"},
-]
-
 [[package]]
 name = "shellingham"
 version = "1.5.4"
@@ -2448,4 +2422,4 @@ test = ["pytest"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.12"
-content-hash = "66cbb12603e0d88dfa1bb766130cf82545db47bc4bd93a2f9320d8ed60a7f189"
+content-hash = "607f15adf3b52bd6f9a1fb613ef0bbf94db4dd3fe501450d5c8cd8876a2191a8"
diff --git a/pyproject.toml b/pyproject.toml
index 74d013a..a279d1c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,6 @@ logfire = {extras = ["fastapi"], version = "^2.1.2"}
 pytest = "^8.3.3"
 httpx = "^0.27.2"
 pytest-cov = "^4.0.0"
-ruff = "^0.0.289"
 pre-commit = "^3.4.0"
 
 [build-system]