github wiki replacement / mkdocs-docs (#2147)

* Add wiki based on mkdocs

* wording fixes

* fix github bg color on narrow

* Fix left sidebar section headers being bigger than pages

* fix hover accent

* fix list rendering on fractional layout

* fix videos

* fix automatic full links

* remove redundant commented css

* improve dark mode contrast

* update pygments for better child node coloring

* update logo

* remove blank lines

* add systemd language hint

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

docs/wiki/FAQ.md

@@ -0,0 +1,65 @@
+### How to disable client-side decorations/make windows rectangular?
+
+Uncomment the [`prefer-no-csd` setting](./Configuration:-Miscellaneous.md#prefer-no-csd) at the top level of the config, and then restart your apps.
+Then niri will ask windows to omit client-side decorations, and also inform them that they are being tiled (which makes some windows rectangular, even if they cannot omit the decorations).
+
+Note that currently this will prevent edge window resize handles from showing up.
+You can still resize windows by holding <kbd>Mod</kbd> and the right mouse button.
+
+### Why are transparent windows tinted? / Why is the border/focus ring showing up through semitransparent windows?
+
+Uncomment the [`prefer-no-csd` setting](./Configuration:-Miscellaneous.md#prefer-no-csd) at the top level of the config, and then restart your apps.
+Niri will draw focus rings and borders *around* windows that agree to omit their client-side decorations.
+
+By default, focus ring and border are rendered as a solid background rectangle behind windows.
+That is, they will show up through semitransparent windows.
+This is because windows using client-side decorations can have an arbitrary shape.
+
+You can also override this behavior with the [`draw-border-with-background` window rule](./Configuration:-Window-Rules.md#draw-border-with-background).
+
+### How to enable rounded corners for all windows?
+
+Put this window rule in your config:
+
+```kdl
+window-rule {
+    geometry-corner-radius 12
+    clip-to-geometry true
+}
+```
+
+For more information, check the [`geometry-corner-radius` window rule](./Configuration:-Window-Rules.md#geometry-corner-radius).
+
+### How to hide the "Important Hotkeys" pop-up at the start?
+
+Put this into your config:
+
+```kdl
+hotkey-overlay {
+    skip-at-startup
+}
+```
+
+### How to run X11 apps like Steam or Discord?
+
+To run X11 apps, you can use [xwayland-satellite](https://github.com/Supreeeme/xwayland-satellite).
+Check [the Xwayland wiki page](./Xwayland.md) for instructions.
+
+Keep in mind that you can run many Electron apps such as VSCode natively on Wayland by passing the right flags, e.g. `code --ozone-platform-hint=auto`
+
+### Why doesn't niri integrate Xwayland like other compositors?
+
+A combination of factors:
+
+- Integrating Xwayland is quite a bit of work, as the compositor needs to implement parts of an X11 window manager.
+- You need to appease the X11 ideas of windowing, whereas for niri I want to have the best code for Wayland.
+- niri doesn't have a good global coordinate system required by X11.
+- You tend to get an endless stream of X11 bugs that take further time and effort away from other tasks.
+- There aren't actually that many X11-only clients nowadays, and xwayland-satellite takes perfect care of most of those.
+- niri isn't a Big Serious Desktop Environment which Must Support All Use Cases (and is Backed By Some Corporation).
+
+All in all, the situation works out in favor of avoiding Xwayland integration.
+
+Also, in the next release niri will have seamless built-in xwayland-satellite integration, that will solve the big rough edge of having to set it up manually.
+
+Besides, I wouldn't be too surprised if, down the road, xwayland-satellite becomes the standard way of integrating Xwayland into new compositors, since it takes on the bulk of the annoying work, and isolates the compositor from misbehaving clients.