I was recently asked to contribute in a latex project which is already relatively large. The main project is in one folder lets call it "project". There ist also another folder called "style", which includes some .cls files and some images. I already found out, how to download submodules recursively via git and now I have a project structure like this:

parent_folder
 |
 +- project
  |
  +- project.tex
 +- style
  |
  +- stylesheet.cls

In project, there is a file project.tex which uses stylesheet.cls like this:

\documentclass[a4paper,11pt]{stylesheet}

When I try to compile project.tex I get an error:

Missing input file: 'stylesheet.cls'

I tried using \documentclass[a4paper,11pt]{style/stylesheet}, but the same error occures. Has anybody an idea how to fix this, whithout changing the whole project structure? Is there something like a latex-makefile? I'm quite new to latex, sorry if I'm asking stupid questions...