JupyterLab Theme Customization

CustomizeJLabTheme.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Modifying a JupyterLab theme\n",
    "\n",
    "Suppose you want to modify the colors and other styles for a particular JupyterLab theme (which we'll call the \"base theme\").\n",
    "\n",
    "Download the `variables.css` file from the base theme into the same directory as this notebook. For example, for the stock dark theme, download https://github.com/jupyterlab/jupyterlab/blob/master/packages/theme-dark-extension/style/variables.css by clicking on the \"Raw\" button and saving the resulting page.\n",
    "\n",
    "To change some parameters in the theme:\n",
    "1. Change the JupyterLab theme to the base theme using the Settings menu.\n",
    "2. Open the `variables.css` you downloaded above and modify whatever parameters you want. You can do this editing in JupyterLab or in a separate editor.\n",
    "3. Run the following code cell to read in the `variables.css` file and apply the changes.\n",
    "\n",
    "Your changes are applied every time you run or rerun the cell below (saving the `variables.css` file alone will not apply your changes).\n",
    "\n",
    "Your customizations are contained in a cell output of this notebook. Clearing outputs in this notebook will remove your customizations and revert back to the base theme."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from IPython.display import display, HTML\n",
    "with open('variables.css') as f:\n",
    "    css = f.read().replace(';', ' !important;')\n",
    "display(HTML('<style type=\"text/css\">%s</style>Customized changes loaded.'%css))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.6.5"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}

@jasongrout Do you know how these changes can be made permanent? I've looked through the Jupyter Lab folder in site-packages but I only find index.css and editing that file doesn't seem to have any effect.

A more permanent solution is probably best left to a theme extension.

I agree with @ian-r-rose. Make a new theme extension using your new variables.css file and install it wherever you like!

Hi @jasongrout, may you specify if it's possible to install a theme extension without having to rebuild the whole extensions stack?

Referring to jupyterlab/jupyterlab#4064, I am afraid this route only works for single users in control of their environment, but not for users of a central system, in need of a custom theme.

Thanks

Hello, i've tested and apparently it did not work

I've made the test with the file given here:

jupyterlab/jupyterlab#3844 (comment)

I run the cell with the code, the file IS on the folder of the notebook and IS in .CSS, but when i execute it, nothing happens. Just the message "Customized changes loaded" but nothing happens. Did the code broke or something? pls help. thanks