How to create a custom JupyterLab css theme extension? - themes

Question

I'm looking for a straight forward way to apply custom CSS to the Jupyter Lab notebook. I've tried following the documentation and am getting the following error:
Missing extension module "lib/index.js"
after running jupyter labextension install .
Jupyter Lab relies on the Themes to adjust the notebook formatting. This seems like a reasonable way of making custom themes reusable, but I'm having a heck of a time figuring out how to make and apply the set of changes I'd like to make.
Following the documentation for Themes linked above:
To quickly create a theme based on the JupyterLab Light Theme, follow
the instructions in the contributing guide and then run jlpm run
create:theme from the repository root directory. Once you select a
name, title and a description, a new theme folder will be created in
the current directory. You can move that new folder to a location of
your choice, and start making desired changes.
The steps in the contributing guide led me to do the following:
Cloned the JupyterLab repo from GitHub using Fork.
pip install -e .
jlpm install
jlpm run build
jlpm run build:core
jupyter lab build
All from my local directory where I cloned the repo. This had the side effect of installing the latest alpha build of JupyterLab, which isn't what I want. I need to be using a stable release so I uninstalled jupyterlab through conda, and then reinstalled it.
I then repeated the above using the 0.35.4 tag of JupyterLab. I only mention this in unlikely event that the double install screwed things up somewhere.
Then, looking at the theme authoring documentation, I first:
npm install, which runs without incident
npm run build, which complains about that ../application/tsconfig.json isn't found which I think is ok because I don't think I'm using any TypeScript (??)
jupyter labextension install . which fails because lib/index.js isn't found.
I presume this is because lib/index.js is listed under "main".
I'm not sure what parts of this config to change and what to leave the same if my only goal is to change the .css files in the style directory.
Here's my full package.json file:
{
"name": "FirstTheme",
"version": "0.19.1",
"description": "My first Theme",
"homepage": "https://github.com/jupyterlab/jupyterlab",
"bugs": {
"url": "https://github.com/jupyterlab/jupyterlab/issues"
},
"license": "BSD-3-Clause",
"author": "Project Jupyter",
"files": [
"lib/*.d.ts",
"lib/*.js.map",
"lib/*.js",
"static/*.css",
"static/*.ttf",
"static/*.eot",
"static/*.woff",
"static/*.woff2"
],
"main": "lib/index.js",
"types": "lib/index.d.ts",
"directories": {
"lib": "lib/"
},
"repository": {
"type": "git",
"url": "https://github.com/jupyterlab/jupyterlab.git"
},
"scripts": {
"build": "tsc -b",
"build:src": "tsc -b src",
"build:webpack": "webpack",
"clean": "rimraf lib && rimraf static",
"prepublishOnly": "npm run build",
"watch": "tsc -b --watch",
"watch:src": "tsc -b src --watch",
"watch:webpack": "webpack --watch"
},
"dependencies": {
"#jupyterlab/application": "^0.19.1",
"#jupyterlab/apputils": "^0.19.1",
"ajv": "^6.7.0",
"font-awesome": "~4.7.0"
},
"devDependencies": {
"css-loader": "~0.28.7",
"mini-css-extract-plugin": "^0.4.0",
"npm-run-all": "~4.1.1",
"rimraf": "~2.6.2",
"svg-url-loader": "~2.3.1",
"svgo": "~1.0.4",
"svgo-loader": "~2.1.0",
"typedoc": "~0.12.0",
"typescript": "~3.1.1",
"url-loader": "~1.0.1",
"webpack": "~4.12.0",
"webpack-cli": "^3.0.3"
},
"publishConfig": {
"access": "public"
},
"jupyterlab": {
"extension": true,
"themeDir": "static"
}
}