diff --git a/CLAUDE.md b/CLAUDE.md
index 34e6dce..44870e5 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -17,9 +17,10 @@ generated data live at:
 ~/.local/state/theme/schedule.json   - Outcome of the last scheduled check
 ~/.cache/theme/backgrounds/          - Pre-rendered backgrounds per theme
 ~/.cache/theme/gowall/               - Per-theme gowall palettes, as JSON
+~/.cache/theme/vivaldi/              - The theme staged for an open Vivaldi, and its waiter's pid
 ```
 
-Generated state belongs in those two cache directories and nowhere else. An app config here is
+Generated state belongs in the cache directories above and nowhere else. An app config here is
 often a symlink into another repo, so writing generated state into it dirties that repo on every
 apply.
 
@@ -59,9 +60,13 @@ beside the others, and an exported config is self-describing.
 Nothing is pruned, deliberately. These are also the directories a user's own themes live in, and
 an installer that deletes what it does not recognize is worse than a few stale kilobytes.
 
-Four apps have no pointer at all. dunst reads `dunstrc.d/` as a directory, firefox and Windows
-Terminal have their real file rewritten, and sioyek gets a managed block spliced into its own
-config.
+These apps have no pointer at all:
+
+- dunst reads `dunstrc.d/` as a directory.
+- firefox and Windows Terminal have their real file rewritten.
+- sioyek gets a managed block spliced into its own config.
+- Vivaldi gets its theme upserted into each profile's `Preferences`, and only while Vivaldi is
+  closed.
 
 `tests/apply-install.bats` pins it, including the two migration cases off the copy-based scheme:
 a `current` left as a real file, and a `current.yazi` left as a real directory, which `ln -sfn`
@@ -350,6 +355,20 @@ CLI verbs. These generators behave unlike the rest:
 - `aerc.sh` relies on aerc.conf pinning `styleset-name = current`, so the applied filename is a contract.
 - `firefox-based.sh` writes one userChrome.css covering Firefox, Zen, Librewolf and Thunderbird.
 - `vscode.sh` is not wired into `theme apply`; run it directly when needed.
+- `vivaldi.sh` emits one entry of Vivaldi's `vivaldi.themes.user` pref, which
+  `lib/vivaldi-preferences.sh` upserts and selects. Vivaldi holds `Preferences` in memory and
+  writes all of it back on exit, so a write while it runs is lost. `apply_vivaldi` therefore
+  installs only into a closed Vivaldi. When Vivaldi is open, it stages the theme in
+  `~/.cache/theme/vivaldi/` and leaves a detached waiter, which installs the staged theme once
+  that Vivaldi's process exits. A staged theme with no waiter is one that never landed, and the
+  next apply warns about it. Nothing outside Vivaldi can change an open window's theme, so the
+  change shows at the next launch. Each dead end, with the command that re-checks it on Arch:
+  - CSS mods are linked once per window: `rg css-mods /opt/vivaldi/resources/vivaldi/window.html`.
+  - `--remote-debugging-port` is refused on the default profile:
+    `strings -a /opt/vivaldi/vivaldi-bin | rg 'non-default data directory'`.
+  - No enterprise policy maps to a `vivaldi.*` pref, so this prints `[]`:
+    `jq '[.policies[].path | select(startswith("vivaldi"))]' /opt/vivaldi/resources/vivaldi/policy_prefs.json`.
+    `BrowserThemeColor` tints Chromium's native toolbar, which Vivaldi does not draw with.
 - `glow.sh` emits a glamour style whose code blocks reach the screen quantized to xterm-256.
   glow never sets glamour's chroma formatter, so only prose keeps true color. `apply_glow` writes
   `glow.yml`'s `style` as an absolute path, because glamour expands neither `~` nor `$HOME` and
diff --git a/README.md b/README.md
index f0498fc..ecfef36 100644
--- a/README.md
+++ b/README.md
@@ -140,11 +140,16 @@ Restart the terminal to see opacity changes.
 theme browsers                # Show detected browsers and theme status
 ```
 
-Firefox-based browsers (Zen, Librewolf, Firefox, Thunderbird) and Chromium are
-themed automatically on `theme apply`. Firefox-based browsers require
+Firefox-based browsers and Vivaldi are themed automatically on `theme apply`.
+Firefox-based browsers require
 `toolkit.legacyUserProfileCustomizations.stylesheets = true` in `about:config`,
 then a restart, for `userChrome.css` to take effect.
 
+Vivaldi gets a native Vivaldi theme, selected for both its light and dark
+schedule. Vivaldi rewrites its own settings when it quits, so an apply while it
+is open waits for it to exit and installs the theme then. The theme shows at its
+next launch.
+
 ### Cross-Machine Sync
 
 Sync your theme preferences across machines using a GitHub Gist:
@@ -197,7 +202,7 @@ Both commands come from [`bashselfupdate`](https://github.com/datapointchris/bas
 - **yazi** — file manager
 - **sioyek** — PDF viewer (custom color mode)
 - **Neovim** — text editor (via colorscheme plugins or generated)
-- **Browsers** — Firefox-based (Zen, Librewolf, Firefox, Thunderbird) and Chromium
+- **Browsers** — Firefox-based (Zen, Librewolf, Firefox, Thunderbird) and Vivaldi
 - **Wallpaper** — themed desktop background, set through Finder on macOS,
   hyprpaper on Hyprland, and the Windows host on WSL
 
diff --git a/bin/theme b/bin/theme
index a0968a0..7f6ca07 100755
--- a/bin/theme
+++ b/bin/theme
@@ -576,7 +576,6 @@ browsers_usage() {
     print_section "Description" "blue"
     cat <<'EOF'
   Show detected browsers and their theme configuration status.
-  Supports Firefox-based browsers: Zen, Librewolf, Firefox, Thunderbird.
 EOF
 
     print_section "Setup Required" "blue"
@@ -600,7 +599,6 @@ Browser Theme Diagnostics
 Description
 -----------
   Show detected browsers and their theme configuration status.
-  Supports Firefox-based browsers: Zen, Librewolf, Firefox, Thunderbird.
 
 Setup Required
 --------------
@@ -840,6 +838,20 @@ show_browsers() {
   echo "    toolkit.legacyUserProfileCustomizations.stylesheets = true"
   echo "  Then restart the browser."
 
+  local vivaldi_dir
+  vivaldi_dir=$(vivaldi_user_data_dir)
+  if [[ -f "$vivaldi_dir/Local State" ]]; then
+    echo ""
+    echo "Vivaldi:"
+    vivaldi_selected_themes "$vivaldi_dir" | sed 's/^/  /'
+    local vivaldi_stranded
+    if vivaldi_stranded=$(vivaldi_stranded_theme); then
+      echo "  Pending: $vivaldi_stranded, never installed. The next theme apply replaces it."
+    elif [[ -f "$VIVALDI_PENDING_THEME" ]]; then
+      echo "  Pending: $(jq -r '.name // .id' "$VIVALDI_PENDING_THEME"), installed when Vivaldi exits"
+    fi
+  fi
+
   # Show chromium status if chromium.theme exists
   local chromium_theme_file="$HOME/.config/chromium/chromium.theme"
   if [[ -f "$chromium_theme_file" ]]; then
diff --git a/lib/generate-all.sh b/lib/generate-all.sh
index 6789b5a..5324cb5 100755
--- a/lib/generate-all.sh
+++ b/lib/generate-all.sh
@@ -52,6 +52,7 @@ declare -A GENERATOR_OUTPUT=(
   ["icons"]="icons.theme"
   ["hyprland-picker"]="hyprland-picker.css"
   ["chromium"]="chromium.theme"
+  ["vivaldi"]="vivaldi.json"
   ["firefox-based"]="userChrome.css"
   ["bat"]="bat.tmTheme"
   ["sioyek"]="sioyek.config"
diff --git a/lib/generators/vivaldi.sh b/lib/generators/vivaldi.sh
new file mode 100755
index 0000000..f5f182d
--- /dev/null
+++ b/lib/generators/vivaldi.sh
@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+# Generate a Vivaldi theme object from theme.yml
+# Usage: vivaldi.sh <theme.yml> [output-file]
+#
+# The object is one entry of Vivaldi's `vivaldi.themes.user` pref, the same
+# shape a theme archive's settings.json carries. `theme apply` upserts it into
+# the profile's Preferences; see lib/vivaldi-preferences.sh.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../theme.sh"
+
+if [[ $# -lt 1 ]]; then
+  echo "Usage: $0 <theme.yml> [output-file]"
+  exit 1
+fi
+
+input_file="$1"
+output_file="${2:-}"
+
+eval "$(load_colors "$input_file")"
+
+UI_ACCENT="${EXTENDED_UI_ACCENT:-$BASE0D}"
+UI_SELECTION="${EXTENDED_UI_SELECTION:-$BASE02}"
+
+# Vivaldi derives every shade, hover and contrast text from the colors below,
+# so the palette's own intermediate slots have nowhere to go.
+#
+# Vivaldi paints its accent across the whole toolbar row and the active tab, so
+# the accent takes the quiet UI selection shade. The loud UI accent goes to
+# highlight, which marks focus and selection.
+generate() {
+  jq -n \
+    --arg id "theme-${THEME_SLUG}" \
+    --arg name "$THEME_NAME" \
+    --arg bg "$SPECIAL_BG" \
+    --arg fg "$SPECIAL_FG" \
+    --arg window "$BASE01" \
+    --arg accent "$UI_SELECTION" \
+    --arg highlight "$UI_ACCENT" \
+    '{
+      engineVersion: 1,
+      version: 1,
+      id: $id,
+      url: "",
+      name: $name,
+      accentFromPage: false,
+      accentOnWindow: false,
+      accentSaturationLimit: 1,
+      backgroundImage: "",
+      backgroundPosition: "stretch",
+      backgroundSource: "",
+      radius: 4,
+      colorAccentBg: $accent,
+      colorBg: $bg,
+      colorFg: $fg,
+      colorHighlightBg: $highlight,
+      colorWindowBg: $window,
+      contrast: 0,
+      preferSystemAccent: false,
+      alpha: 1,
+      blur: 0,
+      transparencyTabs: false,
+      transparencyTabBar: false
+    }'
+}
+
+if [[ -n "$output_file" ]]; then
+  generate >"$output_file"
+  echo "Generated: $output_file"
+else
+  generate
+fi
diff --git a/lib/lib.sh b/lib/lib.sh
index 86aacaf..3a44e32 100755
--- a/lib/lib.sh
+++ b/lib/lib.sh
@@ -16,6 +16,7 @@ THEME_APP_DIR="$(cd "$THEME_LIB_DIR/.." && pwd)"
 # the other, and on Arch that silently skipped Hyprland, Waybar, ghostty, kitty
 # and the wallpaper. storage.sh also owns THEME_STATE_DIR and the history paths.
 source "$THEME_LIB_DIR/storage.sh"
+source "$THEME_LIB_DIR/vivaldi-preferences.sh"
 
 # Always production, unlike THEME_STATE_DIR: apps watch this directory, so dev
 # mode must not point them at .dev-data.
@@ -45,6 +46,7 @@ THEME_APP_ARTIFACTS=(
   "sioyek.config:sioyek"
   "userChrome.css:Firefox-based"
   "chromium.theme:Chromium"
+  "vivaldi.json:Vivaldi"
   "bordersrc:JankyBorders"
   "hyprland.lua:Hyprland"
   "hyprlock.conf:Hyprlock"
@@ -620,6 +622,32 @@ apply_firefox_based() {
   return 0
 }
 
+# Apply Vivaldi theme (macOS and Arch)
+# Prints "at next launch" when Vivaldi is open, and nothing when installed.
+apply_vivaldi() {
+  local theme="$1"
+  local lib_path
+  lib_path=$(get_library_path "$theme")
+
+  if [[ -z "$lib_path" ]] || [[ ! -f "$lib_path/vivaldi.json" ]]; then
+    return 1
+  fi
+
+  local dir
+  dir=$(vivaldi_user_data_dir)
+  [[ -f "$dir/Local State" ]] || return 1
+
+  if vivaldi_running_pid "$dir" >/dev/null; then
+    vivaldi_stage_theme "$lib_path/vivaldi.json" || return 1
+    vivaldi_waiter_running || start_detached "$THEME_LIB_DIR/vivaldi-install-after-exit.sh" "$dir"
+    echo "at next launch"
+    return 0
+  fi
+
+  vivaldi_install_theme "$dir" "$lib_path/vivaldi.json" || return 1
+  rm -f "$VIVALDI_PENDING_THEME"
+}
+
 # Apply sioyek PDF viewer theme (all platforms)
 # Splices a marker-delimited managed block into the user's prefs_user.config.
 #
@@ -2121,6 +2149,22 @@ apply_theme_to_apps() {
     _print_app_status "browsers" "false"
   fi
 
+  # Vivaldi (macOS and Arch)
+  if [[ "$platform" == "macos" ]] || [[ "$platform" == "arch" ]]; then
+    local vivaldi_stranded
+    if vivaldi_stranded=$(vivaldi_stranded_theme); then
+      apply_warn "Vivaldi never got $vivaldi_stranded: it was still open when its waiter stopped. This apply replaces it."
+    fi
+    local vivaldi_status
+    if vivaldi_status=$(apply_vivaldi "$theme" 2>/dev/null); then
+      applied+=("vivaldi")
+      _print_app_status "vivaldi${vivaldi_status:+ ($vivaldi_status)}" "true"
+    else
+      skipped+=("vivaldi")
+      _print_app_status "vivaldi" "false"
+    fi
+  fi
+
   # bat syntax highlighter (all platforms)
   if apply_bat "$theme" 2>/dev/null; then
     applied+=("bat")
@@ -2405,18 +2449,28 @@ reload_dunst() {
   return 1
 }
 
-# Starts a desktop daemon outside the apply's cgroup, which systemd kills when an apply run as a
-# service ends. Hyprland's child sits where login started it. A transient scope is the fallback.
+# Starts a desktop daemon outside the apply's cgroup. Hyprland's child sits where login started
+# it, so the daemon lives as if login had started it. start_detached is the fallback.
 start_session_daemon() {
   local program="$1"
   if command -v hyprctl &>/dev/null \
     && [[ "$(hyprctl dispatch "hl.dsp.exec_cmd('$program')" 2>/dev/null)" == "ok" ]]; then
     return 0
   fi
+  start_detached "$program"
+}
+
+# Starts a command that must outlive the apply. systemd kills a scheduled apply's cgroup when the
+# oneshot exits, so where a systemd user manager runs, the command gets its own transient scope.
+# Elsewhere it gets its own session. On macOS the launchd agent sets AbandonProcessGroup
+# (lib/schedule.sh), which spares it.
+start_detached() {
   if systemctl --user show-environment &>/dev/null; then
-    systemd-run --user --scope --collect --quiet "$program" >/dev/null 2>&1 </dev/null &
+    systemd-run --user --scope --collect --quiet -- "$@" >/dev/null 2>&1 </dev/null &
+  elif command -v setsid &>/dev/null; then
+    setsid "$@" >/dev/null 2>&1 </dev/null &
   else
-    setsid "$program" >/dev/null 2>&1 </dev/null &
+    nohup "$@" >/dev/null 2>&1 </dev/null &
   fi
   disown
 }
diff --git a/lib/vivaldi-install-after-exit.sh b/lib/vivaldi-install-after-exit.sh
new file mode 100755
index 0000000..99d0abf
--- /dev/null
+++ b/lib/vivaldi-install-after-exit.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Install the staged theme into Vivaldi once the Vivaldi holding the given
+# user-data dir has exited. Started detached by apply_vivaldi.
+# Usage: vivaldi-install-after-exit.sh <user-data-dir>
+
+set -euo pipefail
+
+source "$(dirname "${BASH_SOURCE[0]}")/vivaldi-preferences.sh"
+
+vivaldi_install_after_exit "$1"
diff --git a/lib/vivaldi-preferences.sh b/lib/vivaldi-preferences.sh
new file mode 100755
index 0000000..84857b9
--- /dev/null
+++ b/lib/vivaldi-preferences.sh
@@ -0,0 +1,184 @@
+#!/usr/bin/env bash
+# Reads and writes Vivaldi's own profile.
+#
+# Vivaldi keeps its themes in each profile's Preferences and holds that file in
+# memory while it runs, writing all of it back on exit. A write made while it is
+# open is overwritten, so a theme is installed only while Vivaldi is closed. An
+# apply that finds it open stages the theme as pending and leaves a waiter,
+# which installs the pending theme once that Vivaldi exits.
+#
+# The waiter sources only this file, so nothing here reads lib.sh.
+
+VIVALDI_STATE_DIR="$HOME/.cache/theme/vivaldi"
+VIVALDI_PENDING_THEME="$VIVALDI_STATE_DIR/pending-theme.json"
+VIVALDI_WAITER_PID_FILE="$VIVALDI_STATE_DIR/waiter.pid"
+
+vivaldi_user_data_dir() {
+  case "$(uname -s)" in
+    Darwin) echo "$HOME/Library/Application Support/Vivaldi" ;;
+    *) echo "${XDG_CONFIG_HOME:-$HOME/.config}/vivaldi" ;;
+  esac
+}
+
+# A lock or pid file outlives the process that wrote it, and kill -0 answers for
+# whatever process holds the number now, so a pid is trusted only while it still
+# runs the expected program.
+vivaldi_pid_is_vivaldi() {
+  local pid="$1" comm
+  [[ "$pid" =~ ^[0-9]+$ ]] || return 1
+  comm=$(ps -p "$pid" -o comm= 2>/dev/null) || return 1
+  comm="${comm##*/}"
+  [[ "$comm" == vivaldi-bin || "$comm" == Vivaldi ]]
+}
+
+# The pid of the Vivaldi holding this user-data dir, read from Chromium's own
+# SingletonLock symlink, whose target is `<host>-<pid>`. The host is not
+# compared, because macOS renames the host with the network while the lock
+# keeps the name from launch.
+vivaldi_running_pid() {
+  local target pid
+  target=$(readlink "$1/SingletonLock" 2>/dev/null) || return 1
+  pid="${target##*-}"
+  vivaldi_pid_is_vivaldi "$pid" || return 1
+  echo "$pid"
+}
+
+# Each profile directory with its display name, tab-separated, from Local
+# State, which is Vivaldi's own record of its profiles.
+vivaldi_profiles() {
+  jq -r '.profile.info_cache // {} | to_entries[] | [.key, (.value.name // .key)] | @tsv' "$1/Local State"
+}
+
+# Upsert one theme object into every profile's Preferences and select it.
+#
+# Both OS-schedule slots are pointed at it as well as `current`, because
+# Vivaldi's default schedule follows the OS light/dark setting and reads those
+# slots instead of `current`. Every other user theme stays installed. A profile
+# that fails leaves the rest to be installed, and the call returns 1.
+vivaldi_install_theme() {
+  local dir="$1"
+  local theme_json="$2"
+
+  [[ -f "$dir/Local State" && -f "$theme_json" ]] || return 1
+
+  local profiles
+  profiles=$(vivaldi_profiles "$dir") || return 1
+
+  local profile name prefs staged failed=0
+  while IFS=$'\t' read -r profile name; do
+    [[ -n "$profile" ]] || continue
+    prefs="$dir/$profile/Preferences"
+    [[ -f "$prefs" ]] || continue
+
+    # Staged beside the file so the mv is a rename; mktemp's 0600 matches
+    # Chromium's own mode for it.
+    if ! staged=$(mktemp "$prefs.theme.XXXXXX"); then
+      failed=1
+      continue
+    fi
+    if jq -c --slurpfile theme "$theme_json" '
+      $theme[0] as $t
+      | .vivaldi.themes.user = ([(.vivaldi.themes.user // [])[] | select(.id != $t.id)] + [$t])
+      | .vivaldi.themes.current = $t.id
+      | .vivaldi.theme.schedule.o_s = ((.vivaldi.theme.schedule.o_s // {}) + {light: $t.id, dark: $t.id})
+    ' "$prefs" >"$staged" && mv "$staged" "$prefs"; then
+      continue
+    fi
+    rm -f "$staged"
+    failed=1
+  done <<<"$profiles"
+
+  return "$failed"
+}
+
+# What each profile shows, one `<profile name>: <theme>` line apiece. The
+# schedule decides which pref that is: `off` reads `current`, the default
+# `system` reads the OS light and dark slots, and `timeline` reads a list of
+# times this tool never writes. Absent prefs take Vivaldi's own defaults.
+vivaldi_selected_themes() {
+  local dir="$1" profile name
+  while IFS=$'\t' read -r profile name; do
+    [[ -n "$profile" ]] || continue
+    jq -r --arg profile "$name" '
+      ((.vivaldi.themes.user // []) | map({key: .id, value: .name}) | from_entries) as $names
+      | (.vivaldi.theme.schedule // {}) as $s
+      | ($s.o_s // {}) as $o
+      | ($o.light // "Vivaldi1") as $light
+      | ($o.dark // "Vivaldi2") as $dark
+      | ($s.enabled // "system") as $mode
+      | if $mode == "off" or $mode == 0 then ($names[.vivaldi.themes.current // "Vivaldi1"] // (.vivaldi.themes.current // "Vivaldi1"))
+        elif $mode == "timeline" or $mode == 2 then "a timeline schedule"
+        elif $light == $dark then ($names[$light] // $light)
+        else "\($names[$light] // $light) when light, \($names[$dark] // $dark) when dark"
+        end
+      | "\($profile): \(.)"
+    ' "$dir/$profile/Preferences" 2>/dev/null || echo "$name: unreadable"
+  done < <(vivaldi_profiles "$dir")
+}
+
+# The waiter is trusted only while its pid still runs the waiter.
+vivaldi_waiter_running() {
+  local pid args
+  pid=$(cat "$VIVALDI_WAITER_PID_FILE" 2>/dev/null) || return 1
+  [[ "$pid" =~ ^[0-9]+$ ]] || return 1
+  args=$(ps -p "$pid" -o args= 2>/dev/null) || return 1
+  [[ "$args" == *vivaldi-install-after-exit* ]]
+}
+
+# Stage a theme for the waiter. A later apply overwrites it, so the theme that
+# lands is the last one applied while Vivaldi was open.
+vivaldi_stage_theme() {
+  mkdir -p "$VIVALDI_STATE_DIR" || return 1
+  cp "$1" "$VIVALDI_PENDING_THEME.tmp" && mv "$VIVALDI_PENDING_THEME.tmp" "$VIVALDI_PENDING_THEME"
+}
+
+# The name of a staged theme no waiter will install. That is what a waiter
+# leaves when its install failed, or when Vivaldi outlasted it at logout.
+vivaldi_stranded_theme() {
+  [[ -f "$VIVALDI_PENDING_THEME" ]] || return 1
+  vivaldi_waiter_running && return 1
+  jq -r '.name // .id' "$VIVALDI_PENDING_THEME" 2>/dev/null || echo "a theme"
+}
+
+# The waiter's body. It waits for the whole process to exit rather than for the
+# lock to go, since Chromium may drop the lock before its last Preferences write.
+# A Vivaldi relaunched within the poll interval already read the old file, so
+# the wait moves on to that instance. A theme staged during the install is
+# installed on the next pass.
+#
+# A logout or reboot sends SIGTERM to Vivaldi and to this at once. Vivaldi takes
+# a moment to write and exit, so the TERM is answered with a bounded wait rather
+# than by dying first. A failure leaves the theme staged, which the next apply
+# reports.
+vivaldi_install_after_exit() {
+  local dir="$1"
+  local claimed="$VIVALDI_STATE_DIR/installing-theme.json"
+
+  mkdir -p "$VIVALDI_STATE_DIR"
+  echo "$$" >"$VIVALDI_WAITER_PID_FILE"
+  trap 'rm -f "$VIVALDI_WAITER_PID_FILE"' EXIT
+
+  local deadline=""
+  trap 'deadline=$((SECONDS + 15))' TERM HUP
+
+  local pid
+  while [[ -f "$VIVALDI_PENDING_THEME" ]]; do
+    while pid=$(vivaldi_running_pid "$dir"); do
+      while vivaldi_pid_is_vivaldi "$pid"; do
+        if [[ -n "$deadline" ]] && ((SECONDS >= deadline)); then
+          echo "Vivaldi outlasted the session; the staged theme stays pending" >&2
+          return 1
+        fi
+        sleep 1
+      done
+    done
+
+    mv "$VIVALDI_PENDING_THEME" "$claimed" || return 1
+    if ! vivaldi_install_theme "$dir" "$claimed"; then
+      [[ -f "$VIVALDI_PENDING_THEME" ]] || mv "$claimed" "$VIVALDI_PENDING_THEME"
+      echo "Could not install the staged theme into $dir" >&2
+      return 1
+    fi
+    rm -f "$claimed"
+  done
+}
diff --git a/tests/vivaldi-preferences.bats b/tests/vivaldi-preferences.bats
new file mode 100755
index 0000000..588cee9
--- /dev/null
+++ b/tests/vivaldi-preferences.bats
@@ -0,0 +1,37 @@
+#!/usr/bin/env bats
+# Installing a theme into Vivaldi's Preferences.
+#
+# The file is the user's whole browser profile, rewritten in place, so an apply
+# must change nothing but the theme: their own themes and every other pref
+# survive, a reapplied theme is replaced rather than duplicated, and ours is
+# selected under both OS-schedule slots as well as `current`.
+
+load "$HOME/.local/lib/bats-support/load.bash"
+load "$HOME/.local/lib/bats-assert/load.bash"
+
+setup() {
+  load "$BATS_TEST_DIRNAME/helpers.bash"
+  isolate_theme_state
+  source_theme_libs
+
+  vivaldi="$BATS_TEST_TMPDIR/vivaldi"
+  mkdir -p "$vivaldi/Default"
+  printf '{"profile":{"info_cache":{"Default":{}}}}' >"$vivaldi/Local State"
+  printf '{"browser":{"has_seen_welcome_page":true},"vivaldi":{"theme":{"schedule":{"o_s":{"light":"Vivaldi1","dark":"Vivaldi2"}}},"themes":{"user":[{"id":"mine","name":"Mine"}]}}}' \
+    >"$vivaldi/Default/Preferences"
+  printf '{"id":"theme-a","name":"A"}' >"$BATS_TEST_TMPDIR/a.json"
+  printf '{"id":"theme-b","name":"B"}' >"$BATS_TEST_TMPDIR/b.json"
+}
+
+@test "an install keeps the user's themes and prefs and selects the theme" {
+  vivaldi_install_theme "$vivaldi" "$BATS_TEST_TMPDIR/a.json"
+  vivaldi_install_theme "$vivaldi" "$BATS_TEST_TMPDIR/b.json"
+  vivaldi_install_theme "$vivaldi" "$BATS_TEST_TMPDIR/b.json"
+
+  run jq -c '[.vivaldi.themes.user[].id], .vivaldi.themes.current, .vivaldi.theme.schedule.o_s, .browser' \
+    "$vivaldi/Default/Preferences"
+  assert_output '["mine","theme-a","theme-b"]
+"theme-b"
+{"light":"theme-b","dark":"theme-b"}
+{"has_seen_welcome_page":true}'
+}
diff --git a/themes/cendre-medium/vivaldi.json b/themes/cendre-medium/vivaldi.json
new file mode 100644
index 0000000..f8dba63
--- /dev/null
+++ b/themes/cendre-medium/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-cendre-medium",
+  "url": "",
+  "name": "Cendre Medium",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#36241d",
+  "colorBg": "#1d1917",
+  "colorFg": "#e6d5c2",
+  "colorHighlightBg": "#ea9875",
+  "colorWindowBg": "#26211f",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/cendre-soft/vivaldi.json b/themes/cendre-soft/vivaldi.json
new file mode 100644
index 0000000..352790d
--- /dev/null
+++ b/themes/cendre-soft/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-cendre-soft",
+  "url": "",
+  "name": "Cendre Soft",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#3d2b23",
+  "colorBg": "#231f1d",
+  "colorFg": "#e6d5c2",
+  "colorHighlightBg": "#ea9875",
+  "colorWindowBg": "#2d2725",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/cendre/vivaldi.json b/themes/cendre/vivaldi.json
new file mode 100644
index 0000000..3b42126
--- /dev/null
+++ b/themes/cendre/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-cendre",
+  "url": "",
+  "name": "Cendre",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#2f1e17",
+  "colorBg": "#171311",
+  "colorFg": "#e6d5c2",
+  "colorHighlightBg": "#ea9875",
+  "colorWindowBg": "#201b19",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/charcoal-ember/vivaldi.json b/themes/charcoal-ember/vivaldi.json
new file mode 100644
index 0000000..472f3e9
--- /dev/null
+++ b/themes/charcoal-ember/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-charcoal-ember",
+  "url": "",
+  "name": "Charcoal Ember",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#373b41",
+  "colorBg": "#1d1f21",
+  "colorFg": "#c5c8c6",
+  "colorHighlightBg": "#4eb6fe",
+  "colorWindowBg": "#2d2d2d",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/everforest-dark-hard/vivaldi.json b/themes/everforest-dark-hard/vivaldi.json
new file mode 100644
index 0000000..2100853
--- /dev/null
+++ b/themes/everforest-dark-hard/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-everforest-dark-hard",
+  "url": "",
+  "name": "Everforest Dark Hard",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#4c3743",
+  "colorBg": "#1e2326",
+  "colorFg": "#d3c6aa",
+  "colorHighlightBg": "#a7c080",
+  "colorWindowBg": "#2e383c",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/flexoki-moon-black/vivaldi.json b/themes/flexoki-moon-black/vivaldi.json
new file mode 100644
index 0000000..4594c15
--- /dev/null
+++ b/themes/flexoki-moon-black/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-flexoki-moon-black",
+  "url": "",
+  "name": "Flexoki Moon Black",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#343331",
+  "colorBg": "#100f0f",
+  "colorFg": "#cecdc3",
+  "colorHighlightBg": "#3aa99f",
+  "colorWindowBg": "#1c1b1a",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/flexoki-moon-green/vivaldi.json b/themes/flexoki-moon-green/vivaldi.json
new file mode 100644
index 0000000..f786391
--- /dev/null
+++ b/themes/flexoki-moon-green/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-flexoki-moon-green",
+  "url": "",
+  "name": "Flexoki Moon Green",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#2c3b2d",
+  "colorBg": "#08120b",
+  "colorFg": "#ddd8e8",
+  "colorHighlightBg": "#3aa99f",
+  "colorWindowBg": "#151f18",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/flexoki-moon-purple/vivaldi.json b/themes/flexoki-moon-purple/vivaldi.json
new file mode 100644
index 0000000..8efea45
--- /dev/null
+++ b/themes/flexoki-moon-purple/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-flexoki-moon-purple",
+  "url": "",
+  "name": "Flexoki Moon Purple",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#252330",
+  "colorBg": "#12101d",
+  "colorFg": "#ddd8e8",
+  "colorHighlightBg": "#3aa99f",
+  "colorWindowBg": "#1c1a25",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/flexoki-moon-red/vivaldi.json b/themes/flexoki-moon-red/vivaldi.json
new file mode 100644
index 0000000..4de994c
--- /dev/null
+++ b/themes/flexoki-moon-red/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-flexoki-moon-red",
+  "url": "",
+  "name": "Flexoki Moon Red",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#42322e",
+  "colorBg": "#18090b",
+  "colorFg": "#f0e8dd",
+  "colorHighlightBg": "#3aa99f",
+  "colorWindowBg": "#251a1a",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/gruvbox/vivaldi.json b/themes/gruvbox/vivaldi.json
new file mode 100644
index 0000000..c7b03b3
--- /dev/null
+++ b/themes/gruvbox/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-gruvbox",
+  "url": "",
+  "name": "Gruvbox",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#504945",
+  "colorBg": "#1d2021",
+  "colorFg": "#ebdbb2",
+  "colorHighlightBg": "#83a598",
+  "colorWindowBg": "#3c3836",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/kanagawa/vivaldi.json b/themes/kanagawa/vivaldi.json
new file mode 100644
index 0000000..254b8c0
--- /dev/null
+++ b/themes/kanagawa/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-kanagawa",
+  "url": "",
+  "name": "Kanagawa",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#2d4f67",
+  "colorBg": "#1f1f28",
+  "colorFg": "#dcd7ba",
+  "colorHighlightBg": "#7e9cd8",
+  "colorWindowBg": "#16161d",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/nightfox/vivaldi.json b/themes/nightfox/vivaldi.json
new file mode 100644
index 0000000..f8244e7
--- /dev/null
+++ b/themes/nightfox/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-nightfox",
+  "url": "",
+  "name": "Nightfox",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#2b3b51",
+  "colorBg": "#192330",
+  "colorFg": "#cdcecf",
+  "colorHighlightBg": "#719cd6",
+  "colorWindowBg": "#212e3f",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/nordic/vivaldi.json b/themes/nordic/vivaldi.json
new file mode 100644
index 0000000..7140593
--- /dev/null
+++ b/themes/nordic/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-nordic",
+  "url": "",
+  "name": "Nordic",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#3B4252",
+  "colorBg": "#242933",
+  "colorFg": "#BBC3D4",
+  "colorHighlightBg": "#88C0D0",
+  "colorWindowBg": "#2E3440",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/oceanic-next/vivaldi.json b/themes/oceanic-next/vivaldi.json
new file mode 100644
index 0000000..8a6c0d2
--- /dev/null
+++ b/themes/oceanic-next/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-oceanic-next",
+  "url": "",
+  "name": "Oceanic Next",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#4f5b66",
+  "colorBg": "#162c35",
+  "colorFg": "#c0c5ce",
+  "colorHighlightBg": "#6699cc",
+  "colorWindowBg": "#65737e",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/popping-and-locking/vivaldi.json b/themes/popping-and-locking/vivaldi.json
new file mode 100644
index 0000000..3d145e8
--- /dev/null
+++ b/themes/popping-and-locking/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-popping-and-locking",
+  "url": "",
+  "name": "Popping and Locking",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#383637",
+  "colorBg": "#181921",
+  "colorFg": "#ebdbb2",
+  "colorHighlightBg": "#458588",
+  "colorWindowBg": "#252631",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/retrobox/vivaldi.json b/themes/retrobox/vivaldi.json
new file mode 100644
index 0000000..6326ea5
--- /dev/null
+++ b/themes/retrobox/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-retrobox",
+  "url": "",
+  "name": "Retrobox",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#504945",
+  "colorBg": "#1c1c1c",
+  "colorFg": "#ebdbb2",
+  "colorHighlightBg": "#83a598",
+  "colorWindowBg": "#3c3836",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/rose-pine/vivaldi.json b/themes/rose-pine/vivaldi.json
new file mode 100644
index 0000000..2e37bbf
--- /dev/null
+++ b/themes/rose-pine/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-rose-pine",
+  "url": "",
+  "name": "Rose Pine",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#403d52",
+  "colorBg": "#191724",
+  "colorFg": "#e0def4",
+  "colorHighlightBg": "#c4a7e7",
+  "colorWindowBg": "#1f1d2e",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/solarized-osaka/vivaldi.json b/themes/solarized-osaka/vivaldi.json
new file mode 100644
index 0000000..055c95e
--- /dev/null
+++ b/themes/solarized-osaka/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-solarized-osaka",
+  "url": "",
+  "name": "Solarized Osaka",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#073642",
+  "colorBg": "#001419",
+  "colorFg": "#839395",
+  "colorHighlightBg": "#268bd3",
+  "colorWindowBg": "#002b36",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/sora/vivaldi.json b/themes/sora/vivaldi.json
new file mode 100644
index 0000000..0c9a57c
--- /dev/null
+++ b/themes/sora/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-sora",
+  "url": "",
+  "name": "Sora",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#1e2430",
+  "colorBg": "#0e1018",
+  "colorFg": "#c8d0e0",
+  "colorHighlightBg": "#80c8e0",
+  "colorWindowBg": "#14161e",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}
diff --git a/themes/terafox/vivaldi.json b/themes/terafox/vivaldi.json
new file mode 100644
index 0000000..91d7b64
--- /dev/null
+++ b/themes/terafox/vivaldi.json
@@ -0,0 +1,25 @@
+{
+  "engineVersion": 1,
+  "version": 1,
+  "id": "theme-terafox",
+  "url": "",
+  "name": "Terafox",
+  "accentFromPage": false,
+  "accentOnWindow": false,
+  "accentSaturationLimit": 1,
+  "backgroundImage": "",
+  "backgroundPosition": "stretch",
+  "backgroundSource": "",
+  "radius": 4,
+  "colorAccentBg": "#293e40",
+  "colorBg": "#152528",
+  "colorFg": "#e6eaea",
+  "colorHighlightBg": "#5a93aa",
+  "colorWindowBg": "#1d3337",
+  "contrast": 0,
+  "preferSystemAccent": false,
+  "alpha": 1,
+  "blur": 0,
+  "transparencyTabs": false,
+  "transparencyTabBar": false
+}