diff --git a/lib/desktop.sh b/lib/desktop.sh
index 1af12db..35debac 100644
--- a/lib/desktop.sh
+++ b/lib/desktop.sh
@@ -19,7 +19,9 @@ desktop_session_file() {
     # whichever GNOME one is installed (gnome.desktop, gnome-xorg.desktop).
     local f
     if [[ "$(desktop_kind)" == gnome ]]; then
-        for f in /usr/share/wayland-sessions/gnome*.desktop /usr/share/xsessions/gnome*.desktop; do
+        # The plain session, not GNOME Classic (gnome-classic.desktop, from gnome-shell-extensions) or Xorg's.
+        for f in /usr/share/wayland-sessions/gnome.desktop /usr/share/xsessions/gnome.desktop \
+            /usr/share/wayland-sessions/gnome-wayland.desktop; do
             [[ -f "$f" ]] && { basename "$f"; return; }
         done
         echo gnome.desktop
@@ -35,3 +37,14 @@ choose_login_manager() {
     elif [[ "${WANTED[single]:-0}" == 1 ]]; then LOGIN_MANAGER=sddm
     else LOGIN_MANAGER=plasmalogin; fi
 }
+
+desktop_installed() {
+    # desktop_installed kde|gnome: its session is installed (both can be: the
+    # menu then offers the theme of each).
+    local name=plasma f
+    [[ "$1" == gnome ]] && name=gnome
+    for f in /usr/share/wayland-sessions/$name*.desktop /usr/share/xsessions/$name*.desktop; do
+        [[ -f "$f" ]] && return 0
+    done
+    return 1
+}
diff --git a/lib/gnome-theme.sh b/lib/gnome-theme.sh
new file mode 100644
index 0000000..8f69c81
--- /dev/null
+++ b/lib/gnome-theme.sh
@@ -0,0 +1,120 @@
+#!/bin/bash
+# SteamOS look for GNOME, the counterpart of lib/vapor-theme.sh: the Vapor
+# palette from CachyOS's cachyos-vapor package (also the Steam Deck
+# wallpapers), as dark mode, a blue accent, the wallpaper and libadwaita/GTK4
+# colors. Settings go through gsettings and its undo journal (lib/state.sh).
+# Sourced by steamify.sh; not meant to be run on its own.
+
+GNOME_THEME_MARK="/* Steamify GNOME theme */"
+GNOME_THEME_CSS="${XDG_CONFIG_HOME:-$HOME/.config}/gtk-4.0/gtk.css"
+GNOME_THEME_SHELL_DIR="${XDG_DATA_HOME:-$HOME/.local/share}/themes/SteamifyVapor/gnome-shell"
+# The Ubuntu-style look: the dock (Ubuntu Dock is Dash to Dock) and the User
+# Themes extension, which loads the shell theme. (Desktop Icons NG and
+# AppIndicator come with the conversion, lib/desktop-shortcut.sh.)
+GNOME_THEME_PACKAGES=(gnome-shell-extensions)
+GNOME_THEME_EXTENSIONS=(user-theme@gnome-shell-extensions.gcampax.github.com dash-to-dock@micxgx.gmail.com
+    steamify-desktop-start@steamify.github.io)
+# CachyOS's dash-to-dock package (106) doesn't load on GNOME 51: upstream's release, from extensions.gnome.org's tag.
+DOCK_URL="https://github.com/micheleg/dash-to-dock/releases/download/extensions.gnome.org-v110/dash-to-dock@micxgx.gmail.com.zip"
+DOCK_SHA256=3e60680fe7217b905aac4f10deb042e39fcf49168c9b8fdcc5a711bdd49bd3d2
+GNOME_USER_EXTENSIONS="${XDG_DATA_HOME:-$HOME/.local/share}/gnome-shell/extensions"
+GNOME_THEME_WALLPAPER="/usr/share/wallpapers/Steam Deck Logo Default.jpg"
+
+gnometheme_status() {
+    grep -qsF "$GNOME_THEME_MARK" "$GNOME_THEME_CSS"
+}
+
+gnometheme_extensions_install() {
+    # The dock (pinned upstream release) and the start-on-the-desktop extension, in the user's own extensions folder.
+    local zip dir="$GNOME_USER_EXTENSIONS/dash-to-dock@micxgx.gmail.com"
+    if [[ ! -f "$dir/metadata.json" ]] || ! grep -q '"version": 110' "$dir/metadata.json"; then
+        zip="$(mktemp --suffix=.zip)"
+        if curl -fsSL --max-time 60 "$DOCK_URL" -o "$zip" && [[ "$(sha256sum < "$zip")" == "$DOCK_SHA256  -" ]]; then
+            rm -rf "$dir"; mkdir -p "$dir"
+            python3 -c 'import sys,zipfile;zipfile.ZipFile(sys.argv[1]).extractall(sys.argv[2])' "$zip" "$dir"
+            glib-compile-schemas "$dir/schemas" 2>/dev/null
+        else
+            warn "Couldn't download the dock (Dash to Dock 110); it stays off."
+        fi
+        rm -f "$zip"
+    fi
+    dir="$GNOME_USER_EXTENSIONS/steamify-desktop-start@steamify.github.io"
+    mkdir -p "$dir"
+    patch_file steamify-desktop-start.js > "$dir/extension.js"
+    patch_file steamify-desktop-start.json > "$dir/metadata.json"
+}
+
+gnometheme_shell() {
+    # The top bar and dash colors: a shell theme, loaded by User Themes, and the dock beside it.
+    sudo pacman -S --needed --noconfirm "${GNOME_THEME_PACKAGES[@]}" >/dev/null 2>&1 ||
+        { warn "Couldn't install the dock and the shell theme extension; the colors of apps are set."; return 0; }
+    gnometheme_extensions_install
+    mkdir -p "$GNOME_THEME_SHELL_DIR"
+    patch_file steamify-gnome-shell.css > "$GNOME_THEME_SHELL_DIR/gnome-shell.css"
+    gset gnometheme org.gnome.shell.extensions.user-theme name "'SteamifyVapor'" || true
+    # Like Ubuntu's dock: on the left, full height, always there, in Vapor's panel color.
+    local d=org.gnome.shell.extensions.dash-to-dock
+    gset gnometheme $d dock-position "'LEFT'" || true
+    gset gnometheme $d extend-height true || true
+    gset gnometheme $d dock-fixed true || true
+    gset gnometheme $d transparency-mode "'FIXED'" || true
+    gset gnometheme $d custom-background-color true || true
+    gset gnometheme $d background-color "'#24272c'" || true
+    gset gnometheme $d background-opacity 0.95 || true
+    gset gnometheme $d running-indicator-style "'DOTS'" || true
+    gset gnometheme $d custom-theme-shrink true || true
+    local uuid enabled
+    for uuid in "${GNOME_THEME_EXTENSIONS[@]}"; do
+        enabled="$(gs get org.gnome.shell enabled-extensions 2>/dev/null)" || return 0
+        [[ "$enabled" == *"$uuid"* ]] && continue
+        if [[ "$enabled" == "@as []" || "$enabled" == "[]" ]]; then enabled="['$uuid']"
+        else enabled="${enabled%]}, '$uuid']"; fi
+        gset gnometheme org.gnome.shell enabled-extensions "$enabled"
+    done
+}
+
+gnometheme_enable() {
+    if ! pacman -Q cachyos-vapor >/dev/null 2>&1; then
+        info "Installing cachyos-vapor (its wallpapers and colors)..."
+        sudo pacman -S --needed --noconfirm cachyos-vapor || { err "Installing cachyos-vapor failed."; return 1; }
+        # Only remove it again on disable if we were the ones installing it.
+        state_set gnometheme installed_pkg 1
+    fi
+    info "Applying the SteamOS look to GNOME..."
+    gset gnometheme org.gnome.desktop.interface color-scheme "'prefer-dark'"
+    gset gnometheme org.gnome.desktop.interface accent-color "'blue'" || true
+    gset gnometheme org.gnome.desktop.interface gtk-theme "'Vapor'" || true
+    if [[ -f "$GNOME_THEME_WALLPAPER" ]]; then
+        local uri="file://${GNOME_THEME_WALLPAPER// /%20}"
+        gset gnometheme org.gnome.desktop.background picture-uri "'$uri'"
+        gset gnometheme org.gnome.desktop.background picture-uri-dark "'$uri'" || true
+        gset gnometheme org.gnome.desktop.background picture-options "'zoom'"
+    fi
+    # GTK4/libadwaita apps ignore GTK themes: their colors come from this file.
+    mkdir -p "$(dirname "$GNOME_THEME_CSS")"
+    if [[ -f "$GNOME_THEME_CSS" ]] && ! gnometheme_status; then
+        cp -a "$GNOME_THEME_CSS" "$STATE_DIR/gnometheme-gtk4.css"
+    fi
+    { echo "$GNOME_THEME_MARK"; patch_file steamify-gnome-gtk4.css; } > "$GNOME_THEME_CSS"
+    gnometheme_shell
+    ok "SteamOS theme for GNOME on (apps pick up the colors when they start again)."
+}
+
+gnometheme_disable() {
+    info "Restoring GNOME's previous look..."
+    grevert gnometheme
+    rm -rf "${GNOME_THEME_SHELL_DIR%/gnome-shell}" "$GNOME_USER_EXTENSIONS/steamify-desktop-start@steamify.github.io" \
+        "$GNOME_USER_EXTENSIONS/dash-to-dock@micxgx.gmail.com"
+    if [[ -f "$STATE_DIR/gnometheme-gtk4.css" ]]; then
+        mv -f "$STATE_DIR/gnometheme-gtk4.css" "$GNOME_THEME_CSS"
+    else
+        gnometheme_status && rm -f "$GNOME_THEME_CSS"
+    fi
+    if [[ -n "$(state_get gnometheme installed_pkg)" ]]; then
+        # Fails, and stays installed, when the KDE theme or another package needs it.
+        sudo pacman -R --noconfirm cachyos-vapor >/dev/null 2>&1 ||
+            info "Keeping cachyos-vapor installed (another package needs it)."
+    fi
+    state_clear gnometheme
+    ok "Previous GNOME look restored."
+}
diff --git a/lib/menu.sh b/lib/menu.sh
index d697dca..7276c00 100644
--- a/lib/menu.sh
+++ b/lib/menu.sh
@@ -5,7 +5,7 @@
 
 # Menu order. Components are turned on in this order and off in reverse;
 # gaming must come first (single user builds on it).
-COMPONENTS=(gaming boot silent glyphs nvidia bigpicture nvsilent theme single launcher steamgame notify extended_controller_support vram cec machine poweroff kpin hdmi bios)
+COMPONENTS=(gaming boot silent glyphs nvidia bigpicture nvsilent theme gnometheme single launcher steamgame notify extended_controller_support vram cec machine poweroff kpin hdmi bios)
 # One-off actions rather than on/off components: never preselected, never
 # re-applied, not listed as on or off.
 ACTIONS=(bios)
@@ -26,7 +26,7 @@ NO_PRESELECT=(boot silent nvsilent cec kpin hdmi extended_controller_support)
 # FEATURE_BASELINE.
 FEATURE_BASELINE=2.1.0
 declare -A FEATURE_VERSION=(
-    [gaming]=2.9.0 [boot]=2.1.0 [silent]=2.11.0 [nvidia]=2.12.0 [bigpicture]=2.10.0 [nvsilent]=2.11.0 [theme]=2.1.0 [glyphs]=2.1.0 [single]=2.1.0
+    [gaming]=2.9.0 [boot]=2.1.0 [silent]=2.11.0 [nvidia]=2.12.0 [bigpicture]=2.10.0 [nvsilent]=2.11.0 [theme]=2.1.0 [gnometheme]=2.12.0 [glyphs]=2.1.0 [single]=2.1.0
     [launcher]=2.1.0 [cec]=2.7.0 [machine]=2.9.0 [poweroff]=2.2.0 [vram]=2.3.0 [notify]=2.5.0 [steamgame]=2.5.1 [extended_controller_support]=2.10.0
     [kpin]=2.1.0 [hdmi]=2.1.0
 )
@@ -39,6 +39,7 @@ declare -A LABEL=(
     [nvsilent]="Start Steam silently: in the tray at login, no window (untick: Steam's normal window)"
     [bigpicture]="Steam starts in Big Picture: the controller-friendly Steam (untick: Steam's normal window)"
     [theme]="Install SteamOS theme: Vapor look (cachyos-vapor)"
+    [gnometheme]="Install SteamOS theme for GNOME: Vapor look (dark, blue accent, Steam Deck wallpaper)"
     [glyphs]="Install Steam Deck/Machine icons: Deck button icons in gaming mode"
     [single]="Single user mode: no password, lock screen or log out (SDDM)"
     [launcher]="Steamify shortcut: the app on the desktop, Steamify Terminal in the launcher"
@@ -60,8 +61,10 @@ component_available() {
         # The SteamOS conversion is offered on NVIDIA PCs too: it installs the patched gamescope there (lib/gamescope-nvidia.sh)
         # and turns off "Gaming on NVIDIA" (lib/nvidia.sh), which is not offered any more (nvidia_available).
         nvidia|bigpicture|nvsilent) nvidia_available ;;
-        # Plasma only: the Vapor theme and single user mode (KDE Wallet, screen locker, Plasma's menu). Not on GNOME.
-        theme|single) [[ "$(desktop_kind)" == kde ]] ;;
+        # Plasma's Vapor theme and single user mode (KDE Wallet, screen locker, Plasma's menu): when Plasma is installed.
+        # The GNOME theme: when GNOME is. With both installed, each shows.
+        theme|single) desktop_installed kde ;;
+        gnometheme) desktop_installed gnome ;;
         machine|poweroff) machine_available ;;
         vram) vram_available ;;
         # Steamify in the Steam library is for gaming mode's controller: not needed for Big Picture on the desktop (NVIDIA PCs;
diff --git a/lib/state.sh b/lib/state.sh
index 818ee09..14a38ac 100644
--- a/lib/state.sh
+++ b/lib/state.sh
@@ -59,6 +59,40 @@ krevert() {
     rm -f "$journal"
 }
 
+gs() {
+    # gsettings, also without a session (the installer's chroot): then in a
+    # session bus of its own, which writes the user's dconf database.
+    if user_session; then gsettings "$@"; else dbus-run-session -- gsettings "$@"; fi
+}
+
+gset() {
+    # gset <component> <schema> <key> <value>: gsettings (GNOME), recording the
+    # old value in the component's journal like kset does. <value> is in
+    # GVariant text form ('prefer-dark', true, 5). A key the schema lacks
+    # (newer GNOME only) is skipped, returning 1.
+    local component="$1" schema="$2" key="$3" value="$4"
+    local journal="$STATE_DIR/$component.gjournal" old id
+    gs get "$schema" "$key" >/dev/null 2>&1 || return 1
+    mkdir -p "$STATE_DIR"
+    id="$(printf '%s\t%s' "$schema" "$key")"
+    if ! grep -qxF -- "$id" <(cut -f1-2 "$journal" 2>/dev/null); then
+        old="$(gs get "$schema" "$key")"
+        printf '%s\t%s\n' "$id" "$(printf '%s' "$old" | base64 -w0)" >> "$journal"
+    fi
+    gs set "$schema" "$key" "$value"
+}
+
+grevert() {
+    # grevert <component>: put back every gsettings key the component changed.
+    local journal="$STATE_DIR/$1.gjournal" schema key old
+    [[ -f "$journal" ]] || return 0
+    while IFS=$'\t' read -r schema key old; do
+        old="$(printf '%s' "$old" | base64 -d)"
+        gs set "$schema" "$key" "$old" 2>/dev/null || gs reset "$schema" "$key" 2>/dev/null
+    done < <(tac "$journal")
+    rm -f "$journal"
+}
+
 has_journal() {
     [[ -s "$STATE_DIR/$1.journal" ]]
 }
diff --git a/lib/vapor-theme.sh b/lib/vapor-theme.sh
index d9b688a..859c90a 100644
--- a/lib/vapor-theme.sh
+++ b/lib/vapor-theme.sh
@@ -157,7 +157,7 @@ theme_disable() {
     restart_plasmashell_if_stopped
     qdbus6 org.kde.KWin /KWin org.kde.KWin.reconfigure >/dev/null 2>&1 || true
 
-    if [[ -n "$(state_get theme installed_pkg)" ]]; then
+    if [[ -n "$(state_get theme installed_pkg)" ]] && ! gnometheme_status; then
         # Fails, and stays installed, when another package (e.g.
         # cachyos-handheld) depends on it.
         sudo pacman -R --noconfirm cachyos-vapor >/dev/null 2>&1 ||
diff --git a/patches/steamify-desktop-start.js b/patches/steamify-desktop-start.js
new file mode 100644
index 0000000..0a05868
--- /dev/null
+++ b/patches/steamify-desktop-start.js
@@ -0,0 +1,27 @@
+// GNOME opens the overview after login; Ubuntu starts on the desktop. So does
+// this (Steamify GNOME theme): the overview stays closed while the shell
+// starts up, and is available again right after.
+import * as Main from 'resource:///org/gnome/shell/ui/main.js';
+import {Extension} from 'resource:///org/gnome/shell/extensions/extension.js';
+
+export default class SteamifyDesktopStart extends Extension {
+    enable() {
+        if (!Main.layoutManager._startingUp)
+            return;
+        this._hadOverview = Main.sessionMode.hasOverview;
+        Main.sessionMode.hasOverview = false;
+        this._startupId = Main.layoutManager.connect('startup-complete', () => {
+            Main.sessionMode.hasOverview = this._hadOverview;
+            Main.overview.hide();
+        });
+    }
+
+    disable() {
+        if (this._startupId) {
+            Main.layoutManager.disconnect(this._startupId);
+            this._startupId = null;
+        }
+        if (this._hadOverview !== undefined)
+            Main.sessionMode.hasOverview = this._hadOverview;
+    }
+}
diff --git a/patches/steamify-desktop-start.json b/patches/steamify-desktop-start.json
new file mode 100644
index 0000000..ad38c2c
--- /dev/null
+++ b/patches/steamify-desktop-start.json
@@ -0,0 +1,6 @@
+{
+  "uuid": "steamify-desktop-start@steamify.github.io",
+  "name": "Steamify: start on the desktop",
+  "description": "Log in to the desktop, not the overview (like Ubuntu).",
+  "shell-version": ["45", "46", "47", "48", "49", "50", "51"]
+}
diff --git a/patches/steamify-gnome-gtk4.css b/patches/steamify-gnome-gtk4.css
new file mode 100644
index 0000000..b137341
--- /dev/null
+++ b/patches/steamify-gnome-gtk4.css
@@ -0,0 +1,14 @@
+/* Steamify Vapor: libadwaita/GTK4 colors, from Vapor's palette (cachyos-vapor, Vapor.colors). */
+@define-color accent_bg_color #569fcc;
+@define-color accent_fg_color #1f1f26;
+@define-color accent_color #3daee9;
+@define-color window_bg_color #24272c;
+@define-color window_fg_color #eff0f1;
+@define-color view_bg_color #151c23;
+@define-color view_fg_color #eff0f1;
+@define-color headerbar_bg_color #24272c;
+@define-color headerbar_fg_color #eff0f1;
+@define-color card_bg_color #2a2e32;
+@define-color popover_bg_color #2a2e32;
+@define-color sidebar_bg_color #1f2328;
+@define-color dialog_bg_color #2a2e32;
diff --git a/patches/steamify-gnome-shell.css b/patches/steamify-gnome-shell.css
new file mode 100644
index 0000000..2dd75c8
--- /dev/null
+++ b/patches/steamify-gnome-shell.css
@@ -0,0 +1,47 @@
+/* Steamify Vapor: the SteamOS look for GNOME Shell.
+ * Starts from the stock GNOME Shell theme and recolors it with the
+ * palette of the Vapor theme (KDE Plasma's SteamOS look, cachyos-vapor). */
+@import url("resource:///org/gnome/shell/theme/gnome-shell.css");
+
+/* Top bar: Vapor's panel color. */
+#panel,
+#panel.lock-screen,
+#panel.unlock-screen {
+  background-color: #24272c;
+}
+#panel .panel-button { color: #eff0f1; }
+#panel .panel-button:hover,
+#panel .panel-button:focus,
+#panel .panel-button:active,
+#panel .panel-button:checked,
+#panel .panel-button:overview {
+  background-color: rgba(86, 159, 204, 0.35);
+  color: #eff0f1;
+}
+
+/* Dash in the overview, popups and the calendar. */
+#dash .dash-background { background-color: #24272c; }
+.popup-menu-content,
+.candidate-popup-content,
+.message-list-clear-button {
+  background-color: #24272c;
+}
+.popup-menu-item:hover,
+.popup-menu-item:focus,
+.popup-menu-item:active {
+  background-color: rgba(86, 159, 204, 0.35);
+}
+
+/* Selection and focus in Vapor's blue. */
+.app-well-app:focus .overview-icon,
+.app-well-app:selected .overview-icon,
+.overview-tile:focus,
+.overview-tile:selected,
+.search-entry:focus {
+  background-color: rgba(86, 159, 204, 0.3);
+  border-color: #3daee9;
+}
+.button:focus,
+.check-box:focus StBin { border-color: #3daee9; }
+.slider { color: #3daee9; }
+.workspace-thumbnail-indicator { border-color: #3daee9; }
diff --git a/steamify.sh b/steamify.sh
index 1b21594..c0fa518 100755
--- a/steamify.sh
+++ b/steamify.sh
@@ -19,7 +19,7 @@ VERSION=2.12.0
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
-for lib in common state desktop packages login-manager single-user steam-desktop steam-machine fremont-poweroff vram-booster hdmi-refresh nvidia gamescope-nvidia controllers cec boot-session vapor-theme steamos-extras bios desktop-shortcut wizard-shortcut steam-game update-notifier first-login menu backend; do
+for lib in common state desktop packages login-manager single-user steam-desktop steam-machine fremont-poweroff vram-booster hdmi-refresh nvidia gamescope-nvidia controllers cec boot-session vapor-theme gnome-theme steamos-extras bios desktop-shortcut wizard-shortcut steam-game update-notifier first-login menu backend; do
     # shellcheck source=/dev/null
     source "$SCRIPT_DIR/lib/$lib.sh"
 done