I hope that i'm posting this in the right place.
As the title mention, i have a problem with customising the moodle mobile app with a CSS stylesheet. I tried to put the stylesheet in moodle/theme/mytheme/style and moodle/theme folder and added the URL to that stylesheet in the admin > mobile appearance part.
But when i go on my phone, there are no modifications at all. I tried on https://integration.apps.moodledemo.net/ and there, i saw that the stylesheet is blocked due to missing header about CORS policy.
So i then added in webservice/upload.php and webservice/lib.php those lines of code: