arc42.de Website

Live site is hosted by GitHub Pages.

Status

Uptime stats by UptimeRobot.

Content

• General Info
• Local Development
• Custom CSS
• Form Support
• Spam Protection
• Timeline for Courses
• Credits

How does it work?

General

The site is build and created with Jekyll and Markdown. It uses the MinimalMistakes template, with a few slight modifications

• home.md is the homepage, it's mapped (via permalink) to "/".
• Most content is organized in markdown files under the _pages directory (a convention from Jekyll).

Local development

Prerequisite: Local build uses Docker. You need Docker installed, nothing else — no local Ruby or gems required.

First-time setup (and whenever the Gemfile changes):

make lock     # regenerate Gemfile.lock cleanly inside a one-shot Ruby container
make build    # bake the gems into the Docker image

make lock runs in a clean ruby:3.3-slim container, so the lockfile is deterministic regardless of the host OS / arch. It registers both x86_64-linux and aarch64-linux platforms, which keeps Intel and Apple Silicon developers in sync. You only need to re-run it when you edit the Gemfile.

make build then bundle installs into the image's /usr/local/bundle. The dev server runs against those baked gems — never against anything on the host — so the host can't shadow them.

The Minimal Mistakes theme is vendored into this repository. After make build, make dev starts from the cached Docker image and local theme files; it must not fetch the remote theme at startup.

Start the dev server:

make dev

Starts Jekyll on http://localhost:4000, watching for file changes. No gem installation or remote theme download happens at startup — it runs from the cached image and local repository files.

All useful commands:

• make lock — regenerate Gemfile.lock from scratch (run after Gemfile edits, or once if the lock is broken)
• make build — build (or rebuild) the Docker image with all dependencies
• make dev — start Jekyll locally (requires a prior make build)
• make dev PORT=4001 — start on a different port
• make test-theme — build with Docker networking disabled and assert that local theme files are sufficient
• make down — stop and remove the Docker Compose services
• make clean — remove the generated _site directory
• make rebuild — clean + build + dev (full reset)

Offline theme check

Run this after changing theme files, Jekyll configuration, or Docker dependencies:

make test-theme

The check runs the already-built arc42-jekyll image with Docker networking disabled. It fails if Jekyll logs indicate a remote theme fetch, a missing Liquid include/layout, or if representative generated pages such as /, /overview/, /termine/, /anmeldung/, /about/, /articles/, /recommendations/, /gallery/, or /videos/ are missing.

Internal page routes use directory-style URLs with trailing slashes, for example permalink: /imprint/ and links such as /imprint/. This keeps local Jekyll development, GitHub Pages, and generated links aligned. make test-theme also fails if a future change reintroduces top-level name.html page output, generated internal links without the trailing slash, stale sitemap URLs, or same-site navigation links that point at 0.0.0.0, www.arc42.de, or absolute https://arc42.de/... anchors.

Updating the vendored theme

The site vendors Minimal Mistakes 4.24.0 locally instead of using remote_theme. To update the theme later:

1. Download the exact upstream Minimal Mistakes release you want to use.
2. Copy upstream additions into _layouts, _includes, _sass, _data, and assets/js.
3. Preserve local overrides such as _includes/head.html, _includes/masthead.html, _includes/footer.html, custom timeline includes, custom feature-row includes, and assets/css/main.scss.
4. Run a clean build and smoke-check /, /overview/, /termine/, /anmeldung/, /about/, /articles/, /recommendations/, /gallery/, and /videos/.
5. Start make dev without network access after make build to verify no remote theme fetch is required.

Custom css

• The timeline (in /termine/) is based upon w3schools
  • We configure the timeline with yaml.
• Some buttons are also based upon w3schools definition.

Custom css is located in /assets/css, the required import statement in /assets/css/main.scss

Form support (for "Anmeldung") and

We use formspark.io as backend provider for our "Anmeldung".

Spam protection

For spam protection within the form, we use Botpoison, see especially their getting started with HTML article:

1.Import the @botpoison/browser script.
2. Add your public key to the data-botpoison-public-key attribute.
3. The solution will automatically be attached to the submission (as the _botpoison field).

1: Integrate Botpoison script

A botpoison browser script is required for spam-protection in the Anmeldung-Form, see https://documentation.formspark.io/setup/spam-protection.html#botpoison

We make this a page-specific asset (see https://www.instapaper.com/read/1436398846) by adding the following yaml to anmeldung.md:

---
title: "Anmeldung"
layout: single
permalink: /anmeldung/

botpoison: nospam

---

And then adding the appropriate import statement in _includes/head/custom.html:

{% if page.botpoison %}
 <!-- 1. Import the @botpoison/browser script -->
<script src="https://unpkg.com/@botpoison/browser"></script>
{% endif %}

2: Add required info to form

1. Create the Botpoison publik and secret keys, as explained in Botpoison setup guide
2. In your form's settings, select Botpoison under Spam Protection.
3. Copy the secret key, paste it into the Botpoison secret key field in the Formspark form configuration
4. Add the Botpoison public key to the HTML of the form:

<form
      method="POST"
      action="https://submit-form.com/your-form-id"
      data-botpoison-public-key="your-botpoison-public-key"
      target="_blank"
>

In our concrete case, that looks as follows (file _pages/anmeldung.md)

<form action="https://submit-form.com/AIKiYyJP"
      data-botpoison-public-key="pk_8e195655-38ed-4eec-a445-a1e0d68a488d">

3: Formating of Anmeldung-Email

Formating of the email sent from formspark.io to arc42 is done via handlebar configuration within the Formspark.io website.

<div style="text-align: left;">
  <strong>Neue Anmeldung (über arc42):</strong><br>
  {{data.vorname}} {{data.nachname}} ({{data.email}}) hat<br>

<div style="margin: 16px 0;">
  {{#if data.nachnameTN}}
    <h3>{{data.vornameTN}} {{data.nachnameTN}} ({{data.emailTN}})</h3>
  {{else}}
    <h3>sich selbst</h3>
  {{/if}}
  <br>
für den Kurs {{data.kursdatum}} angemeldet.
</div>
<br>
  Rechnungsadresse: <br>
  <div style="margin: 16px 0;">
  {{data.Rechnungsadresse}} <br>
  </div>
 <br>
  Bemerkung:<br>
  <div style="margin: 16px 0;">
   {{data.comment}} 
  </div>
<br>

</div>

Ensure JavaScript is available

As often, StackOverflow had an answer, we combine a <noscript> tag with a <div> and a small JavaScript function:

<body>
<div id="main_body" style="display: none;">
all content - not displayed...
</div>
</body>

Plus a small JavaScript function to enable the content again...

<script type="text/javascript">
document.getElementById("main_body").style.display="block";
</script>

It does NOT work if users disable JavaScript when already on the form...

Timeline for Courses

The /termine/ page uses a modular timeline system for easy course management:

Adding/Updating Courses

Edit the courses: array in _pages/termine.md front matter:

courses:
  - type: "msa"                    # Course type: msa, msa_online, req4arc, improve, adoc
    date: "2.-5. Dezember 2025"    # Course dates
    location: "München"            # Location (omit for online courses)
    anchor_id: "msa-dec-2025"      # Unique ID for deep linking
    sold_out: true                 # Optional: marks course as sold out
    few_seats: "Nur noch wenige Plätze verfügbar"  # Optional: warning for limited availability
    pricing: "Frühbucherpreis: €2690"  # Optional: custom pricing text

CAREFUL: This configuration is based upon YAML, and is therefore sensitive to spaces and tabs. Ensure you use EXACTLY four spaces for indentation. Otherwise you will waste precious lifetime debugging yaml.

Deep Linking

Each course gets a unique anchor: https://arc42.de/termine/#msa-dec-2025

Course Types

• msa - German MSA courses (in-person)
• msa_online - English MSA courses (online, Wolfgang Reimesch)
• req4arc - REQ4ARC courses
• improve - IMPROVE courses
• adoc - ADOC courses

The system automatically handles left/right timeline positioning and consistent formatting.

Credits

Site theme

Thanx to Michael Rose, creator of the Minimal-Mistakes Jekyll Theme, follow him on Twitter.

Icons + Images:

• Free images can be found at Unsplash
• I generated the various favicon files with RealFavIconGenerator.

---

Licenses

arc42 Template

The arc42 template is licensed under a CreativeCommons Sharealike International 4.0 License.

You are free to:

• Share — copy and redistribute the template in any medium or format
• Adapt — remix, transform, and build upon the material for any purpose, even commercially.

Website Theme: MIT License (MIT)

Copyright (c) 2016ff Michael Rose

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.