patched_app.py

from competitions.app import app
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import Response


FULL_WIDTH_CSS = """
<style>
  main .prose,
  main .markdown-body,
  main [class*="max-w-"],
  main [class*="container"],
  .prose,
  .markdown-body {
    max-width: none !important;
  }

  main {
    max-width: none !important;
  }
</style>
"""


class InjectCssMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        response = await call_next(request)
        content_type = response.headers.get("content-type", "")
        if "text/html" not in content_type:
            return response

        body = b""
        async for chunk in response.body_iterator:
            body += chunk

        html = body.decode("utf-8", errors="ignore")
        if "</head>" in html and FULL_WIDTH_CSS not in html:
            html = html.replace("</head>", FULL_WIDTH_CSS + "</head>")

        headers = dict(response.headers)
        headers.pop("content-length", None)
        return Response(
            content=html,
            status_code=response.status_code,
            headers=headers,
            media_type=response.media_type,
        )


app.add_middleware(InjectCssMiddleware)