docs: snapshot pre-OIDC state and fix sidebar overlap on scroll

Create documentation snapshot (23-10-2025) for legacy OIDC setup before
Authorization Code Flow + PKCE migration. Add link from current docs to
legacy version for users on older Nebraska versions.

Also fix sidebar title being hidden when navbar shrinks on scroll:
- Add dynamic padding compensation to sidebar when navbar shrinks
- Use shared transition timing variables for smooth animations
- Compensation scalar (0.9) ensures title remains visible
- Simplify docs-section padding to consistent 130px across breakpoints

Signed-off-by: Ervin Rácz <ervin.racz@protonmail.com>

Author: ervcz

content/docs/.gitignore

@@ -1 +1 @@
-_index.md
+/_index.md

content/docs/23-10-2025/_index.md

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+---
+content_type: flatcar
+title: Flatcar Container Linux
+main_menu: true
+weight: 39
+---
+
+Flatcar Container Linux is a container optimized OS that ships a minimal OS
+image, which includes only the tools needed to run containers. The OS is
+shipped through an immutable filesystem and includes automatic atomic
+updates.
+
+
+### Getting Started
+
+If you're new to Flatcar and if you're looking for a brief introduction on getting Flatcar up and running, please have a look at our [quickstart guide][quick-start].
+
+### Installing Flatcar
+
+Flatcar Container Linux runs on most cloud providers, virtualization
+platforms and bare metal servers. 
+
+#### Cloud Providers
+ * [Amazon EC2][ec2]
+ * [Microsoft Azure][azure]
+ * [Google Compute Engine][gce]
+ * [Equinix Metal][equinix-metal]
+ * [VMware][vmware]
+ * [DigitalOcean][digital-ocean]
+ * [Hetzner][hetzner]
+ * [OpenStack][openstack]
+ * [Brightbox][brightbox]
+ * [Scaleway][scaleway] (community support)
+ * [OVHcloud][ovhcloud] (community support)
+ * [Akamai/Linode][akamai]
+ * [STACKIT][stackit]
+
+#### Virtualization options
+It's easy to run a local Flatcar VM on your laptop for testing and debugging
+purposes. You can use any of the following options.
+
+ * [QEMU][qemu]
+ * [libVirt][libvirt]
+ * [VirtualBox][virtualbox] (community support)
+ * [Vagrant][vagrant] (community support)
+ * [Hyper-V][hyper-v] (community support)
+ * [KubeVirt][kubevirt] (community support)
+ * [Proxmox VE][proxmoxve] (community support)
+
+#### Bare Metal
+You can install Flatcar on bare metal machines in different ways: using ISO
+images, booting from PXE or iPXE, and even by running an installation
+script on an existing Linux system.
+
+ * [Installing from ISO images][boot-iso]
+ * [Booting with PXE][pxe]
+ * [Booting with iPXE][ipxe]
+ * [Installing with flatcar-install][install-to-disk]
+
+If you want to provide metadata to your baremetal machines, we recommend
+using [Matchbox][matchbox].
+
+#### Upgrading from CoreOS Container Linux
+
+Flatcar Container Linux is a drop-in replacement of CoreOS Container Linux.
+If you are a CoreOS Container Linux user looking for a replacement,
+checkout our guides to [migrate from CoreOS Container
+Linux][migrate-from-container-linux], or you can [update from CoreOS
+Container Linux][update-from-container-linux] directly.
+
+### Provisioning Tools
+
+[Ignition][ignition-what] is the recommended way to provision Flatcar
+Container Linux at first boot.  Ignition uses a JSON configuration file,
+and it is recommended to generate it from the [Container Linux
+Config][container-linux-config] YAML format, which has additional features.
+The [Container Linux Config Transpiler][config-transpiler] converts a
+Container Linux Config to an Ignition config.
+
+ * [Understanding the Boot Process][ignition-boot]
+ * [Configuring the Network with Ignition][ignition-network]
+ * [Using metadata during provisioning][ignition-metadata]
+ * [Getting started with Butane][config-intro]
+ * [Examples of using Butane][config-examples]
+ * [Using Terraform to provision Flatcar Container Linux][terraform]
+ * [Extending the base OS with systemd-sysext images][sysext]
+
+### Setting Flatcar Up and Common Operations
+
+Follow these guides to connect your machines together as a cluster,
+configure machine parameters, create users, inject multiple SSH keys, and
+more.
+
+#### Customizing Flatcar
+ * [Using networkd to customize networking][networkd-customize]
+ * [Using systemd drop-in units][systemd-drop-in]
+ * [Using environment variables in systemd units][environment-variables-systemd]
+ * [Using systemd and udev rules][udev-rules]
+ * [Using NVIDIA GPUs on Flatcar][using-nvidia]
+ * [Scheduling tasks with systemd timers][tasks-with-systemd]
+ * [Configuring DNS][dns]
+ * [Configuring date & timezone][date-timezone]
+ * [Adding users][users]
+ * [Kernel modules / sysctl parameters][parameters]
+ * [Adding swap][swap]
+ * [Power management][power-management]
+ * [ACPI][acpi]
+
+#### Managing Releases and Updates
+ * [Switching release channels][release-channels]
+ * [Configuring the update strategy][update-strategies]
+ * [Flatcar update configuration specification][update-conf]
+ * [Verifying Flatcar Images with GPG][verify-container-linux]
+ * [Nebraska][nebraska]
+
+#### Creating Clusters
+ * [Cluster architectures][cluster-architectures]
+ * [Clustering machines][clustering-machines]
+ * [Using Amazon EC2 Container Service][ec2-container-service]
+
+#### Managing Storage
+ * [Using RAID for the root filesystem][filesystem-placement]
+ * [Adding disk space][disk-space]
+ * [Mounting storage][mounting-storage]
+ * [iSCSI configuration][iscsi]
+ * [ZFS Extension][zfsextension]
+
+#### Additional security options
+ * [Setting up LUKS disk encryption][luks-encryption]
+ * [Customizing the SSH daemon][ssh-daemon]
+ * [Configuring SSSD on Flatcar Container Linux][sssd-container-linux]
+ * [Hardening a Flatcar Container Linux machine][hardening-container-linux]
+ * [Trusted Computing Hardware Requirements][hardware-requirements]
+ * [Adding Cert Authorities][cert-authorities]
+ * [Using SELinux][selinux]
+ * [Disabling SMT][disabling-smt]
+ * [Enabling FIPS][enabling-fips]
+ * [Using the audit subsystem][audit-system]
+
+#### Debugging Flatcar
+ * [Install debugging tools][debugging-tools]
+ * [Working with btrfs][btrfs]
+ * [Reading the system log][system-log]
+ * [Collecting crash logs][crash-log]
+ * [Manual Flatcar Container Linux rollbacks][container-linux-rollbacks]
+
+### Container Runtimes
+Flatcar Container Linux supports all of the popular methods for running
+containers, and you can choose to interact with the containers at a
+low-level, or use a higher level orchestration framework. Listed below are
+some guides to help you choose and make use of the different runtimes.
+
+ * [Getting started with Docker][docker]
+ * [Customizing Docker][customizing-docker]
+ * [Using systemd to manage Docker containers][manage-docker-containers]
+ * [Use a custom Docker or containerd version][use-a-custom-docker-or-containerd-version]
+ * [Authenticating to Container registries][registry-authentication]
+ * [Getting started with Kubernetes][kubernetes]
+ * [High availability Kubernetes][ha-kubernetes]
+
+### Developer guides and Reference
+APIs and troubleshooting guides for working with Flatcar Container Linux.
+
+* [Developer guides][developer-guides]: Comprehensive guides on developing for Flatcar, working with the SDK, and on building and extending OS images.
+* [Integrations][integrations]
+* [Migrating from cloud-config to Container Linux Config][migrating-from-cloud-config]
+* [Flatcar Supply Chain Security (SLSA and SPDX SBOM)][supply-chain-security] detailing security mechanisms employed at build / release time as well as at run-time to ensure validity of inputs processed and outputs shipped.
+
+### Tutorial
+Flatcar tutorial to deep dive into some Flatcar fundamental concepts.
+* [Introduction][tutorial-introduction]
+* [Hands-on 1: Discovering][tutorial-hands-on-1]
+* [Hands-on 2: Provisioning][tutorial-hands-on-2]
+* [Hands-on 3: Deploying][tutorial-hands-on-3]
+* [Hands-on 4: Updating][tutorial-hands-on-4]
+
+[quick-start]: installing
+[supply-chain-security]: reference/supply-chain
+[ignition-what]: provisioning/ignition/
+[ignition-boot]: provisioning/ignition/boot-process
+[ignition-network]: provisioning/ignition/network-configuration
+[ignition-metadata]: provisioning/ignition/dynamic-data
+[container-linux-config]: provisioning/cl-config/
+[config-transpiler]: provisioning/config-transpiler/
+[config-intro]: provisioning/config-transpiler/getting-started
+[config-dynamic-data]: provisioning/config-transpiler/dynamic-data
+[config-examples]: provisioning/config-transpiler/examples
+[matchbox]: https://matchbox.psdn.io/
+[ipxe]: installing/bare-metal/booting-with-ipxe
+[pxe]: installing/bare-metal/booting-with-pxe
+[install-to-disk]: installing/bare-metal/installing-to-disk
+[boot-iso]: installing/bare-metal/booting-with-iso
+[filesystem-placement]: setup/storage/raid
+[migrate-from-container-linux]: migrating-from-coreos/
+[update-from-container-linux]: migrating-from-coreos/update-from-container-linux
+[ec2]: installing/cloud/aws-ec2
+[digital-ocean]: installing/cloud/digitalocean
+[gce]: installing/cloud/gcp
+[azure]: installing/cloud/azure
+[qemu]: installing/vms/qemu
+[equinix-metal]: installing/cloud/equinix-metal
+[libvirt]: installing/vms/libvirt
+[virtualbox]: installing/vms/virtualbox
+[vagrant]: installing/vms/vagrant
+[hyper-v]: installing/vms/hyper-v
+[kubevirt]: installing/vms/kubevirt
+[proxmoxve]: installing/community-platforms/proxmoxve
+[vmware]: installing/cloud/vmware
+[cluster-architectures]: setup/clusters/architectures
+[update-strategies]: setup/releases/update-strategies
+[clustering-machines]: setup/clusters/discovery
+[verify-container-linux]: setup/releases/verify-images
+[networkd-customize]: setup/customization/network-config-with-networkd
+[systemd-drop-in]: setup/systemd/drop-in-units
+[environment-variables-systemd]: setup/systemd/environment-variables
+[dns]: setup/customization/configuring-dns
+[date-timezone]: setup/customization/configuring-date-and-timezone
+[users]: setup/customization/adding-users
+[parameters]: setup/customization/other-settings
+[disk-space]: setup/storage/adding-disk-space
+[mounting-storage]: setup/storage/mounting-storage
+[power-management]: setup/customization/power-management
+[registry-authentication]: container-runtimes/registry-authentication
+[iscsi]: setup/storage/iscsi
+[swap]: setup/storage/adding-swap
+[zfsextension]: setup/storage/zfs
+[ec2-container-service]: setup/clusters/booting-on-ecs/
+[manage-docker-containers]: setup/systemd/getting-started
+[udev-rules]: setup/systemd/udev-rules
+[update-conf]: setup/releases/update-conf
+[release-channels]: setup/releases/switching-channels
+[tasks-with-systemd]: setup/systemd/timers
+[luks-encryption]: setup/security/luks
+[ssh-daemon]: setup/security/customizing-sshd
+[sssd-container-linux]: setup/security/sssd
+[hardening-container-linux]: setup/security/hardening-guide
+[hardware-requirements]: setup/security/trusted-computing-hardware-requirements
+[cert-authorities]: setup/security/adding-certificate-authorities
+[selinux]: setup/security/selinux
+[disabling-smt]: setup/security/disabling-smt
+[enabling-fips]: setup/security/fips
+[audit-system]: setup/security/audit
+[debugging-tools]: setup/debug/install-debugging-tools
+[btrfs]: setup/debug/btrfs-troubleshooting
+[system-log]: setup/debug/reading-the-system-log
+[crash-log]: setup/debug/collecting-crash-logs
+[container-linux-rollbacks]: setup/debug/manual-rollbacks
+[docker]: container-runtimes/getting-started-with-docker
+[customizing-docker]: container-runtimes/customizing-docker
+[use-a-custom-docker-or-containerd-version]: container-runtimes/use-a-custom-docker-or-containerd-version
+[developer-guides]: reference/developer-guides/
+[integrations]: reference/integrations/
+[migrating-from-cloud-config]: provisioning/cl-config/from-cloud-config
+[containerd-for-kubernetes]: container-runtimes/switching-from-docker-to-containerd-for-kubernetes
+[terraform]: provisioning/terraform/
+[hetzner]: installing/cloud/hetzner
+[sysext]: provisioning/sysext/
+[acpi]: setup/customization/ACPI
+[openstack]: installing/cloud/openstack
+[brightbox]: installing/cloud/brightbox
+[kubernetes]: container-runtimes/getting-started-with-kubernetes
+[ha-kubernetes]: container-runtimes/high-availability-kubernetes
+[using-nvidia]: setup/customization/using-nvidia
+[tutorial-introduction]: tutorial/
+[tutorial-hands-on-1]: tutorial/hands-on-1
+[tutorial-hands-on-2]: tutorial/hands-on-2
+[tutorial-hands-on-3]: tutorial/hands-on-3
+[tutorial-hands-on-4]: tutorial/hands-on-4
+[scaleway]: installing/community-platforms/scaleway
+[ovhcloud]: installing/community-platforms/ovhcloud
+[akamai]: installing/cloud/akamai
+[nebraska]: nebraska
+[stackit]: installing/cloud/stackit

content/docs/23-10-2025/container-runtimes/_index.md

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+---
+title: Container Runtimes
+description: >
+  Flatcar Container Linux supports all of the popular methods for running
+  containers, and you can choose to interact with the containers at a
+  low-level, or use a higher level orchestration framework. These guides
+  can help you choose and use the different container runtimes supported.
+weight: 60
+---
+

content/docs/23-10-2025/contribute/_index.md

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+---
+title: How to Contribute
+content_type: contribute
+weight: 130
+---
+
+Flatcar documentation is released under the [Apache 2.0 License][asl], and we welcome contributions. Check out the [help-wanted tag][help-wanted] in this project's Issues list for good places to start participating.
+
+Submit fixes and additions in the form of [GitHub *Pull Requests* (PRs)][pull-requests]. The general process is the typical git fork-branch-PR-review-merge cycle:
+
+1. Fork this repository into your GitHub account
+2. Make changes in a topic branch or your fork's `master`
+3. Send a Pull Request from that topic branch to flatcar/flatcar-website
+4. Maintainers will review the PR and either merge it or make comments
+
+Cognizance of the tribal customs described and linked to below will help get your contributions incorporated with the greatest of ease.
+
+## Clear commit messages
+
+Commit messages follow a format that makes clear **what** changed and **why** it changed. The first line of each commit message should clearly state what module or file changed, summarize the change very briefly, and should end, without a period, somewhere short of 70 characters. After a blank line, the body of the commit message should then explain why the change was needed, with lines wrapped at 72 characters wide and sentences normally punctuated. Cite related issues or previous revisions as appropriate. For example:
+
+```
+ignition: Update etcd example to use %m
+
+Make the etcd configuration example use ignition's %m instead of the
+ETCD_NAME environment variable. Fixes #123.
+```
+
+This format can be described somewhat more formally as:
+
+```
+<module or file name>: <what changed>
+<BLANK LINE>
+<why this change was made>
+<BLANK LINE>
+[<footer>]
+```
+
+Where the optional `[<footer>]` might include `signed-off-by` lines and other metadata.
+
+## Style guide
+
+The [style guide][style] prescribes the conventions of formatting and English style preferred in Flatcar project documentation.
+
+## Translations
+
+We happily accept accurate translations. Please send the documents as a pull request and follow two guidelines:
+
+1. Name the files identically to the originals, but put them beneath a directory named for the translation's `gettext` locale. For example: `JA_JP/doc`, `ZH_CN/doc,` or `KO_KN/doc`.
+
+2. Add an explanation about the translated document to the top of the file: "These documents were translated into Esperanto by Community Member <person@example.com> and last updated on 2015-12-01. If you find inaccuracies or problems please file an issue on GitHub."
+
+
+[asl]: https://github.com/flatcar/flatcar-docs/blob/main/LICENSE
+[flatcar-docs]: https://flatcar.org/docs/latest/
+[help-wanted]: https://github.com/flatcar/Flatcar/labels/kind%2Fdocs
+[pull-requests]: https://help.github.com/articles/using-pull-requests/
+[style]: docs