Unable to call custom.css file



I’m trying to call my cutom.css file in the header.ejs file. At first I had the file in a separate dir so I thought the dir was written wrong, but even after I moved it to the root directory, it still won’t load. Gives me a 404 error. By the way, other stylesheets (like BS and font awesome CDNs) are working fine. Please help!

Here’s my code:
link rel=“stylesheet” href="/custom.css"

And the directory:
fgraciolli:~/workspace $ ls
app.js custom.css data/ models/ mongod* node_modules/ package.json views/

And the error:
GET https://the-editoria-fgraciolli.c9users.io/custom.css 404 (Not Found)