diff --git a/Cargo.lock b/Cargo.lock
index 768c2b3..83265c4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -108,7 +108,7 @@ dependencies = [
  "hashbrown 0.16.1",
  "static_assertions",
  "windows",
- "windows-core 0.62.2",
+ "windows-core",
 ]
 
 [[package]]
@@ -1409,7 +1409,7 @@ dependencies = [
  "roxmltree",
  "smallvec",
  "windows",
- "windows-core 0.62.2",
+ "windows-core",
  "yeslogic-fontconfig-sys",
 ]
 
@@ -2109,7 +2109,7 @@ dependencies = [
  "js-sys",
  "log",
  "wasm-bindgen",
- "windows-core 0.58.0",
+ "windows-core",
 ]
 
 [[package]]
@@ -3904,10 +3904,11 @@ dependencies = [
 
 [[package]]
 name = "rcalc"
-version = "0.1.11"
+version = "0.1.20"
 dependencies = [
  "slint",
  "slint-build",
+ "winresource",
 ]
 
 [[package]]
@@ -5430,7 +5431,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "527fadee13e0c05939a6a05d5bd6eec6cd2e3dbd648b9f8e447c6518133d8580"
 dependencies = [
  "windows-collections",
- "windows-core 0.62.2",
+ "windows-core",
  "windows-future",
  "windows-numerics",
 ]
@@ -5441,20 +5442,7 @@ version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "23b2d95af1a8a14a3c7367e1ed4fc9c20e0a26e79551b1454d72583c97cc6610"
 dependencies = [
- "windows-core 0.62.2",
-]
-
-[[package]]
-name = "windows-core"
-version = "0.58.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ba6d44ec8c2591c134257ce647b7ea6b20335bf6379a27dac5f1641fcf59f99"
-dependencies = [
- "windows-implement 0.58.0",
- "windows-interface 0.58.0",
- "windows-result 0.2.0",
- "windows-strings 0.1.0",
- "windows-targets 0.52.6",
+ "windows-core",
 ]
 
 [[package]]
@@ -5463,11 +5451,11 @@ version = "0.62.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8e83a14d34d0623b51dce9581199302a221863196a1dde71a7663a4c2be9deb"
 dependencies = [
- "windows-implement 0.60.2",
- "windows-interface 0.59.3",
+ "windows-implement",
+ "windows-interface",
  "windows-link",
- "windows-result 0.4.1",
- "windows-strings 0.5.1",
+ "windows-result",
+ "windows-strings",
 ]
 
 [[package]]
@@ -5476,22 +5464,11 @@ version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e1d6f90251fe18a279739e78025bd6ddc52a7e22f921070ccdc67dde84c605cb"
 dependencies = [
- "windows-core 0.62.2",
+ "windows-core",
  "windows-link",
  "windows-threading",
 ]
 
-[[package]]
-name = "windows-implement"
-version = "0.58.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2bbd5b46c938e506ecbce286b6628a02171d56153ba733b6c741fc627ec9579b"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.119",
-]
-
 [[package]]
 name = "windows-implement"
 version = "0.60.2"
@@ -5503,17 +5480,6 @@ dependencies = [
  "syn 2.0.119",
 ]
 
-[[package]]
-name = "windows-interface"
-version = "0.58.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "053c4c462dc91d3b1504c6fe5a726dd15e216ba718e84a0e46a88fbe5ded3515"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.119",
-]
-
 [[package]]
 name = "windows-interface"
 version = "0.59.3"
@@ -5537,19 +5503,10 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6e2e40844ac143cdb44aead537bbf727de9b044e107a0f1220392177d15b0f26"
 dependencies = [
- "windows-core 0.62.2",
+ "windows-core",
  "windows-link",
 ]
 
-[[package]]
-name = "windows-result"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d1043d8214f791817bab27572aaa8af63732e11bf84aa21a45a78d6c317ae0e"
-dependencies = [
- "windows-targets 0.52.6",
-]
-
 [[package]]
 name = "windows-result"
 version = "0.4.1"
@@ -5559,16 +5516,6 @@ dependencies = [
  "windows-link",
 ]
 
-[[package]]
-name = "windows-strings"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cd9b125c486025df0eabcb585e62173c6c9eddcec5d117d3b6e8c30e2ee4d10"
-dependencies = [
- "windows-result 0.2.0",
- "windows-targets 0.52.6",
-]
-
 [[package]]
 name = "windows-strings"
 version = "0.5.1"
@@ -5805,6 +5752,16 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "winresource"
+version = "0.1.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0986a8b1d586b7d3e4fe3d9ea39fb451ae22869dcea4aa109d287a374d866087"
+dependencies = [
+ "toml",
+ "version_check",
+]
+
 [[package]]
 name = "wit-bindgen"
 version = "0.57.1"
diff --git a/Cargo.toml b/Cargo.toml
index 36addfb..b55fb72 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "rcalc"
-version = "0.1.12"
+version = "0.1.21"
 edition = "2021"
 build = "build.rs"
 
@@ -9,3 +9,4 @@ slint = "1.11"
 
 [build-dependencies]
 slint-build = "1.11"
+winresource = "0.1"
diff --git a/assets/icon.ico b/assets/icon.ico
new file mode 100644
index 0000000..41982f0
Binary files /dev/null and b/assets/icon.ico differ
diff --git a/build.rs b/build.rs
index 3c966ff..d7c37fe 100644
--- a/build.rs
+++ b/build.rs
@@ -7,9 +7,35 @@ fn main() {
     let version = resolve_app_version();
     println!("cargo:rustc-env=APP_VERSION={version}");
 
+    embed_windows_icon();
+
     slint_build::compile("ui/app.slint").expect("Slint build failed");
 }
 
+/// Shell icon for `rcalc.exe` in Explorer (needs `assets/icon.ico` + windres/rc).
+fn embed_windows_icon() {
+    let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap_or_default();
+    if target_os != "windows" {
+        return;
+    }
+
+    println!("cargo:rerun-if-changed=assets/icon.ico");
+
+    let mut res = winresource::WindowsResource::new();
+    res.set_icon("assets/icon.ico");
+
+    // Cross-compile from Linux: mingw windres is prefixed.
+    if cfg!(not(windows)) {
+        let target = env::var("TARGET").unwrap_or_default();
+        if target.contains("windows-gnu") {
+            res.set_windres_path("x86_64-w64-mingw32-windres");
+        }
+    }
+
+    res.compile()
+        .expect("failed to embed Windows icon (is windres/rc available?)");
+}
+
 /// Window / package version shown as `Rcalc-{version}`.
 ///
 /// On each `release` build the patch in `Cargo.toml` is incremented once
diff --git a/dist/libwinpthread-1.dll b/dist/libwinpthread-1.dll
index d87e531..7dbabd0 100755
Binary files a/dist/libwinpthread-1.dll and b/dist/libwinpthread-1.dll differ
diff --git a/dist/rcalc b/dist/rcalc
index c28d62c..37d272e 100755
Binary files a/dist/rcalc and b/dist/rcalc differ
diff --git a/dist/rcalc.exe b/dist/rcalc.exe
index 6628869..b5b625e 100755
Binary files a/dist/rcalc.exe and b/dist/rcalc.exe differ
diff --git a/dist/rcalc_0.1.20.tar b/dist/rcalc_0.1.20.tar
new file mode 100644
index 0000000..069bff0
Binary files /dev/null and b/dist/rcalc_0.1.20.tar differ
diff --git a/dist/rcalc_0120.zip b/dist/rcalc_0120.zip
new file mode 100644
index 0000000..fcec75c
Binary files /dev/null and b/dist/rcalc_0120.zip differ
diff --git a/dist/win_rcalc.zip b/dist/win_rcalc.zip
index 07759c9..c38ca2d 100644
Binary files a/dist/win_rcalc.zip and b/dist/win_rcalc.zip differ
diff --git a/src/config.rs b/src/config.rs
new file mode 100644
index 0000000..dbc4ceb
--- /dev/null
+++ b/src/config.rs
@@ -0,0 +1,248 @@
+//! Persistent app settings (`~/.config/rcalc/config.json` or `%APPDATA%\rcalc\config.json`).
+
+use std::fs;
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ThemeId {
+    Dark = 0,
+    Light = 1,
+    Blue = 2,
+}
+
+impl ThemeId {
+    pub fn from_i32(v: i32) -> Self {
+        match v {
+            1 => Self::Light,
+            2 => Self::Blue,
+            _ => Self::Dark,
+        }
+    }
+
+    pub fn as_i32(self) -> i32 {
+        self as i32
+    }
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::Dark => "Dark",
+            Self::Light => "Light",
+            Self::Blue => "Blue",
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct AppConfig {
+    /// Button size: 1 = compact, 2 = normal, 3 = large.
+    pub button_size: u8,
+    pub theme: ThemeId,
+    /// Last calculator mode index (0..4).
+    pub last_mode: u8,
+    pub show_bits: bool,
+    /// Programmer word size label: QWORD, DWORD, DINT, WORD, INT, BYTE.
+    pub word_size: String,
+}
+
+impl Default for AppConfig {
+    fn default() -> Self {
+        Self {
+            button_size: 2,
+            theme: ThemeId::Dark,
+            last_mode: 0,
+            show_bits: true,
+            word_size: "QWORD".into(),
+        }
+    }
+}
+
+impl AppConfig {
+    pub fn load() -> Self {
+        let path = config_path();
+        let Ok(raw) = fs::read_to_string(&path) else {
+            return Self::default();
+        };
+        Self::from_json(&raw).unwrap_or_default()
+    }
+
+    pub fn save(&self) {
+        let path = config_path();
+        if let Some(parent) = path.parent() {
+            let _ = fs::create_dir_all(parent);
+        }
+        let _ = fs::write(path, self.to_json());
+    }
+
+    pub fn clamp_button_size(size: u8) -> u8 {
+        size.clamp(1, 3)
+    }
+
+    fn to_json(&self) -> String {
+        format!(
+            "{{\n  \"button_size\": {},\n  \"theme\": {},\n  \"last_mode\": {},\n  \"show_bits\": {},\n  \"word_size\": \"{}\"\n}}\n",
+            self.button_size,
+            self.theme.as_i32(),
+            self.last_mode,
+            self.show_bits,
+            self.word_size
+        )
+    }
+
+    fn from_json(raw: &str) -> Option<Self> {
+        let mut cfg = Self::default();
+        for line in raw.lines() {
+            let line = line.trim().trim_end_matches(',');
+            if let Some(v) = json_u8(line, "button_size") {
+                cfg.button_size = Self::clamp_button_size(v);
+            } else if let Some(v) = json_i32(line, "theme") {
+                cfg.theme = ThemeId::from_i32(v);
+            } else if let Some(v) = json_u8(line, "last_mode") {
+                cfg.last_mode = v.min(4);
+            } else if let Some(v) = json_bool(line, "show_bits") {
+                cfg.show_bits = v;
+            } else if let Some(v) = json_string(line, "word_size") {
+                let upper = v.to_ascii_uppercase();
+                if matches!(
+                    upper.as_str(),
+                    "QWORD" | "DWORD" | "DINT" | "WORD" | "INT" | "BYTE"
+                ) {
+                    cfg.word_size = upper;
+                }
+            }
+        }
+        Some(cfg)
+    }
+}
+
+fn json_u8(line: &str, key: &str) -> Option<u8> {
+    json_i32(line, key)?.try_into().ok()
+}
+
+fn json_i32(line: &str, key: &str) -> Option<i32> {
+    let prefix = format!("\"{key}\"");
+    let idx = line.find(&prefix)?;
+    let rest = &line[idx + prefix.len()..];
+    let rest = rest.trim_start().trim_start_matches(':').trim_start();
+    rest.split(|c: char| c == ',' || c == '}' || c.is_whitespace())
+        .next()?
+        .parse()
+        .ok()
+}
+
+fn json_bool(line: &str, key: &str) -> Option<bool> {
+    let prefix = format!("\"{key}\"");
+    let idx = line.find(&prefix)?;
+    let rest = &line[idx + prefix.len()..];
+    let rest = rest.trim_start().trim_start_matches(':').trim_start();
+    if rest.starts_with("true") {
+        Some(true)
+    } else if rest.starts_with("false") {
+        Some(false)
+    } else {
+        None
+    }
+}
+
+fn json_string(line: &str, key: &str) -> Option<String> {
+    let prefix = format!("\"{key}\"");
+    let idx = line.find(&prefix)?;
+    let rest = &line[idx + prefix.len()..];
+    let rest = rest.trim_start().trim_start_matches(':').trim_start();
+    let rest = rest.strip_prefix('"')?;
+    let end = rest.find('"')?;
+    Some(rest[..end].to_string())
+}
+
+pub fn config_path() -> PathBuf {
+    config_dir().join("config.json")
+}
+
+fn config_dir() -> PathBuf {
+    #[cfg(windows)]
+    {
+        if let Some(appdata) = std::env::var_os("APPDATA") {
+            return PathBuf::from(appdata).join("rcalc");
+        }
+    }
+    #[cfg(not(windows))]
+    {
+        if let Some(xdg) = std::env::var_os("XDG_CONFIG_HOME") {
+            return PathBuf::from(xdg).join("rcalc");
+        }
+        if let Some(home) = std::env::var_os("HOME") {
+            return PathBuf::from(home).join(".config").join("rcalc");
+        }
+    }
+    PathBuf::from(".")
+}
+
+/// RGB colors for a theme (applied to Slint global).
+pub struct ThemeColors {
+    pub bg: (u8, u8, u8),
+    pub surface: (u8, u8, u8),
+    pub btn: (u8, u8, u8),
+    pub btn_hover: (u8, u8, u8),
+    pub digit: (u8, u8, u8),
+    pub digit_hover: (u8, u8, u8),
+    pub accent: (u8, u8, u8),
+    pub accent_hover: (u8, u8, u8),
+    pub text: (u8, u8, u8),
+    pub text_muted: (u8, u8, u8),
+    pub text_dim: (u8, u8, u8),
+    pub menu_active: (u8, u8, u8),
+    pub eq_text: (u8, u8, u8),
+    pub border: (u8, u8, u8),
+}
+
+pub fn theme_colors(id: ThemeId) -> ThemeColors {
+    match id {
+        ThemeId::Dark => ThemeColors {
+            bg: (0x20, 0x20, 0x20),
+            surface: (0x2a, 0x2a, 0x2a),
+            btn: (0x32, 0x32, 0x32),
+            btn_hover: (0x46, 0x46, 0x46),
+            digit: (0x3b, 0x3b, 0x3b),
+            digit_hover: (0x50, 0x50, 0x50),
+            accent: (0x60, 0xcd, 0xff),
+            accent_hover: (0x78, 0xd7, 0xff),
+            text: (0xff, 0xff, 0xff),
+            text_muted: (0xc8, 0xc8, 0xc8),
+            text_dim: (0x9a, 0x9a, 0x9a),
+            menu_active: (0x2f, 0x3a, 0x42),
+            eq_text: (0x14, 0x14, 0x14),
+            border: (0x40, 0x40, 0x40),
+        },
+        ThemeId::Light => ThemeColors {
+            bg: (0xf3, 0xf3, 0xf3),
+            surface: (0xff, 0xff, 0xff),
+            btn: (0xe6, 0xe6, 0xe6),
+            btn_hover: (0xd0, 0xd0, 0xd0),
+            digit: (0xff, 0xff, 0xff),
+            digit_hover: (0xee, 0xee, 0xee),
+            accent: (0x00, 0x78, 0xd4),
+            accent_hover: (0x1a, 0x86, 0xda),
+            text: (0x1a, 0x1a, 0x1a),
+            text_muted: (0x55, 0x55, 0x55),
+            text_dim: (0x77, 0x77, 0x77),
+            menu_active: (0xd6, 0xeb, 0xf8),
+            eq_text: (0xff, 0xff, 0xff),
+            border: (0xcc, 0xcc, 0xcc),
+        },
+        ThemeId::Blue => ThemeColors {
+            bg: (0x0f, 0x1c, 0x2e),
+            surface: (0x16, 0x28, 0x40),
+            btn: (0x1e, 0x3a, 0x5f),
+            btn_hover: (0x2a, 0x4d, 0x7a),
+            digit: (0x24, 0x45, 0x6e),
+            digit_hover: (0x2f, 0x58, 0x88),
+            accent: (0x4f, 0xc3, 0xf7),
+            accent_hover: (0x81, 0xd4, 0xfa),
+            text: (0xec, 0xf5, 0xff),
+            text_muted: (0xb0, 0xc4, 0xde),
+            text_dim: (0x7f, 0x9b, 0xb8),
+            menu_active: (0x1a, 0x3a, 0x5c),
+            eq_text: (0x0a, 0x14, 0x22),
+            border: (0x2a, 0x4a, 0x6e),
+        },
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 28bb7eb..82e7c5e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,7 @@
 // Hide the extra console window on Windows GUI builds.
 #![cfg_attr(all(windows, not(debug_assertions)), windows_subsystem = "windows")]
 
+mod config;
 mod convert;
 mod crc;
 mod engine;
@@ -10,11 +11,12 @@ mod programmer;
 use std::cell::RefCell;
 use std::rc::Rc;
 
+use config::{theme_colors, AppConfig, ThemeId};
 use convert::{ConvField, ConvPanel, Converter, Endian, RatioWidth};
 use crc::CrcTool;
 use engine::{Calculator, Op, StdPanel};
 use engineering::Engineering;
-use programmer::{Base, ProgOp, Programmer};
+use programmer::{Base, ProgOp, Programmer, WordSize};
 use slint::{ComponentHandle, ModelRc, VecModel};
 
 slint::include_modules!();
@@ -26,6 +28,42 @@ enum Mode {
     Programmer,
     Convert,
     Crc,
+    Settings,
+}
+
+impl Mode {
+    fn from_u8(v: u8) -> Self {
+        match v {
+            1 => Self::Engineering,
+            2 => Self::Programmer,
+            3 => Self::Convert,
+            4 => Self::Crc,
+            5 => Self::Settings,
+            _ => Self::Standard,
+        }
+    }
+
+    fn as_u8(self) -> u8 {
+        match self {
+            Self::Standard => 0,
+            Self::Engineering => 1,
+            Self::Programmer => 2,
+            Self::Convert => 3,
+            Self::Crc => 4,
+            Self::Settings => 5,
+        }
+    }
+
+    fn title(self) -> &'static str {
+        match self {
+            Self::Standard => "Standard",
+            Self::Engineering => "Engineering",
+            Self::Programmer => "Programmer",
+            Self::Convert => "Convert",
+            Self::Crc => "CRC",
+            Self::Settings => "Settings",
+        }
+    }
 }
 
 struct State {
@@ -37,19 +75,26 @@ struct State {
     crc: CrcTool,
     show_bits: bool,
     win_profile: u32,
+    config: AppConfig,
 }
 
 impl Default for State {
     fn default() -> Self {
+        let config = AppConfig::load();
+        let mut prog = Programmer::new();
+        if let Some(ws) = WordSize::from_label(&config.word_size) {
+            prog.set_word_size(ws);
+        }
         Self {
-            mode: Mode::Standard,
+            mode: Mode::from_u8(config.last_mode),
             std: Calculator::new(),
             eng: Engineering::new(),
-            prog: Programmer::new(),
+            prog,
             conv: Converter::new(),
             crc: CrcTool::new(),
-            show_bits: true,
+            show_bits: config.show_bits,
             win_profile: u32::MAX,
+            config,
         }
     }
 }
@@ -85,8 +130,11 @@ fn run_app() -> Result<(), slint::PlatformError> {
     ui.set_app_title(format!("Rcalc-{}", env!("APP_VERSION")).into());
 
     let state = Rc::new(RefCell::new(State::default()));
-
-    refresh(&ui, &mut state.borrow_mut());
+    {
+        let mut s = state.borrow_mut();
+        apply_ui_style(&ui, &s.config);
+        refresh(&ui, &mut s);
+    }
 
     let ui_weak = ui.as_weak();
     let state_keys = state.clone();
@@ -94,6 +142,7 @@ fn run_app() -> Result<(), slint::PlatformError> {
         let mut s = state_keys.borrow_mut();
         handle_key(&mut s, id.as_str());
         if let Some(ui) = ui_weak.upgrade() {
+            apply_ui_style(&ui, &s.config);
             refresh(&ui, &mut s);
         }
     });
@@ -111,6 +160,44 @@ fn run_app() -> Result<(), slint::PlatformError> {
     ui.run()
 }
 
+fn rgb(c: (u8, u8, u8)) -> slint::Color {
+    slint::Color::from_rgb_u8(c.0, c.1, c.2)
+}
+
+fn apply_ui_style(ui: &AppWindow, cfg: &AppConfig) {
+    let style = ui.global::<UiStyle>();
+    style.set_size(i32::from(cfg.button_size));
+    style.set_theme(cfg.theme.as_i32());
+    let c = theme_colors(cfg.theme);
+    style.set_bg(rgb(c.bg));
+    style.set_surface(rgb(c.surface));
+    style.set_btn(rgb(c.btn));
+    style.set_btn_hover(rgb(c.btn_hover));
+    style.set_digit(rgb(c.digit));
+    style.set_digit_hover(rgb(c.digit_hover));
+    style.set_accent(rgb(c.accent));
+    style.set_accent_hover(rgb(c.accent_hover));
+    style.set_text(rgb(c.text));
+    style.set_text_muted(rgb(c.text_muted));
+    style.set_text_dim(rgb(c.text_dim));
+    style.set_menu_active(rgb(c.menu_active));
+    style.set_eq_text(rgb(c.eq_text));
+    style.set_border(rgb(c.border));
+
+    ui.set_cfg_button_size(i32::from(cfg.button_size));
+    ui.set_cfg_theme(cfg.theme.as_i32());
+}
+
+fn persist_config(state: &mut State) {
+    if state.mode != Mode::Settings {
+        state.config.last_mode = state.mode.as_u8();
+    }
+    state.config.show_bits = state.show_bits;
+    state.config.word_size = state.prog.word_size().label().to_string();
+    state.config.button_size = AppConfig::clamp_button_size(state.config.button_size);
+    state.config.save();
+}
+
 fn install_panic_hook() {
     let default = std::panic::take_hook();
     std::panic::set_hook(Box::new(move |info| {
@@ -173,13 +260,7 @@ fn bit_row_model(row: &[(bool, u32)]) -> ModelRc<BitInfo> {
 }
 
 fn window_profile(state: &State) -> u32 {
-    let mode = match state.mode {
-        Mode::Standard => 0,
-        Mode::Engineering => 1,
-        Mode::Programmer => 2,
-        Mode::Convert => 3,
-        Mode::Crc => 4,
-    };
+    let mode = u32::from(state.mode.as_u8());
     let bits = if state.show_bits {
         state.prog.word_size().bits()
     } else {
@@ -190,7 +271,9 @@ fn window_profile(state: &State) -> u32 {
         ConvPanel::Ratio => 1,
         ConvPanel::Ascii => 2,
     };
-    mode * 1000 + bits * 10 + panel
+    let size = u32::from(state.config.button_size);
+    let theme = state.config.theme.as_i32() as u32;
+    mode * 100_000 + bits * 1000 + panel * 100 + size * 10 + theme
 }
 
 fn fit_window(ui: &AppWindow, state: &mut State) {
@@ -200,6 +283,12 @@ fn fit_window(ui: &AppWindow, state: &mut State) {
     }
     state.win_profile = profile;
 
+    let scale = match state.config.button_size {
+        1 => 0.92,
+        3 => 1.12,
+        _ => 1.0,
+    };
+
     let (w, h) = match state.mode {
         Mode::Standard => (360.0, 580.0),
         Mode::Engineering => (420.0, 720.0),
@@ -218,9 +307,10 @@ fn fit_window(ui: &AppWindow, state: &mut State) {
         }
         Mode::Convert => (420.0, 820.0),
         Mode::Crc => (460.0, 560.0),
+        Mode::Settings => (420.0, 420.0),
     };
     ui.window()
-        .set_size(slint::LogicalSize::new(w as f32, h as f32));
+        .set_size(slint::LogicalSize::new((w * scale) as f32, (h * scale) as f32));
 }
 
 fn apply_crc_results(ui: &AppWindow, state: &State) {
@@ -236,24 +326,11 @@ fn apply_crc_results(ui: &AppWindow, state: &State) {
 }
 
 fn refresh(ui: &AppWindow, state: &mut State) {
-    ui.set_mode(match state.mode {
-        Mode::Standard => 0,
-        Mode::Engineering => 1,
-        Mode::Programmer => 2,
-        Mode::Convert => 3,
-        Mode::Crc => 4,
-    });
-    ui.set_mode_title(
-        match state.mode {
-            Mode::Standard => "Standard",
-            Mode::Engineering => "Engineering",
-            Mode::Programmer => "Programmer",
-            Mode::Convert => "Convert",
-            Mode::Crc => "CRC",
-        }
-        .into(),
-    );
+    ui.set_mode(i32::from(state.mode.as_u8()));
+    ui.set_mode_title(state.mode.title().into());
     ui.set_menu_open(false);
+    ui.set_cfg_button_size(i32::from(state.config.button_size));
+    ui.set_cfg_theme(state.config.theme.as_i32());
 
     fit_window(ui, state);
 
@@ -335,29 +412,75 @@ fn refresh(ui: &AppWindow, state: &mut State) {
             ui.set_crc_input(state.crc.input().into());
             apply_crc_results(ui, state);
         }
+        Mode::Settings => {}
     }
 }
 
+fn set_mode(state: &mut State, mode: Mode) {
+    state.mode = mode;
+    persist_config(state);
+}
+
 fn handle_key(state: &mut State, id: &str) {
     match id {
         "mode:std" => {
-            state.mode = Mode::Standard;
+            set_mode(state, Mode::Standard);
             return;
         }
         "mode:eng" => {
-            state.mode = Mode::Engineering;
+            set_mode(state, Mode::Engineering);
             return;
         }
         "mode:prog" => {
-            state.mode = Mode::Programmer;
+            set_mode(state, Mode::Programmer);
             return;
         }
         "mode:conv" => {
-            state.mode = Mode::Convert;
+            set_mode(state, Mode::Convert);
             return;
         }
         "mode:crc" => {
-            state.mode = Mode::Crc;
+            set_mode(state, Mode::Crc);
+            return;
+        }
+        "mode:settings" => {
+            state.mode = Mode::Settings;
+            return;
+        }
+        "cfg:size:1" => {
+            state.config.button_size = 1;
+            state.win_profile = u32::MAX;
+            persist_config(state);
+            return;
+        }
+        "cfg:size:2" => {
+            state.config.button_size = 2;
+            state.win_profile = u32::MAX;
+            persist_config(state);
+            return;
+        }
+        "cfg:size:3" => {
+            state.config.button_size = 3;
+            state.win_profile = u32::MAX;
+            persist_config(state);
+            return;
+        }
+        "cfg:theme:0" => {
+            state.config.theme = ThemeId::Dark;
+            state.win_profile = u32::MAX;
+            persist_config(state);
+            return;
+        }
+        "cfg:theme:1" => {
+            state.config.theme = ThemeId::Light;
+            state.win_profile = u32::MAX;
+            persist_config(state);
+            return;
+        }
+        "cfg:theme:2" => {
+            state.config.theme = ThemeId::Blue;
+            state.win_profile = u32::MAX;
+            persist_config(state);
             return;
         }
         _ => {}
@@ -368,7 +491,7 @@ fn handle_key(state: &mut State, id: &str) {
         Mode::Engineering => handle_engineering(&mut state.eng, id),
         Mode::Programmer => handle_programmer(state, id),
         Mode::Convert => handle_convert(&mut state.conv, id),
-        Mode::Crc => {}
+        Mode::Crc | Mode::Settings => {}
     }
 }
 
@@ -456,6 +579,13 @@ fn handle_standard(calc: &mut Calculator, id: &str) {
 fn handle_programmer(state: &mut State, id: &str) {
     if id == "bits" {
         state.show_bits = !state.show_bits;
+        persist_config(state);
+        return;
+    }
+
+    if id == "word" {
+        state.prog.cycle_word_size();
+        persist_config(state);
         return;
     }
 
@@ -476,7 +606,6 @@ fn handle_programmer(state: &mut State, id: &str) {
         "base:dec" => calc.set_base(Base::Dec),
         "base:oct" => calc.set_base(Base::Oct),
         "base:bin" => calc.set_base(Base::Bin),
-        "word" => calc.cycle_word_size(),
         "+" => calc.set_op(ProgOp::Add),
         "-" | "−" => calc.set_op(ProgOp::Sub),
         "*" | "×" => calc.set_op(ProgOp::Mul),
diff --git a/src/programmer.rs b/src/programmer.rs
index dbe1c24..3c5683e 100644
--- a/src/programmer.rs
+++ b/src/programmer.rs
@@ -75,6 +75,18 @@ impl WordSize {
         }
     }
 
+    pub fn from_label(s: &str) -> Option<Self> {
+        match s.trim().to_ascii_uppercase().as_str() {
+            "QWORD" => Some(WordSize::Qword),
+            "DWORD" => Some(WordSize::Dword),
+            "DINT" => Some(WordSize::Dint),
+            "WORD" => Some(WordSize::Word),
+            "INT" => Some(WordSize::Int),
+            "BYTE" => Some(WordSize::Byte),
+            _ => None,
+        }
+    }
+
     pub fn cycle(self) -> Self {
         match self {
             WordSize::Qword => WordSize::Dword,
@@ -310,7 +322,17 @@ impl Programmer {
             }
             self.typing = false;
         }
-        self.word_size = self.word_size.cycle();
+        self.set_word_size(self.word_size.cycle());
+    }
+
+    pub fn set_word_size(&mut self, size: WordSize) {
+        if self.typing {
+            if let Ok(v) = parse_entry(&self.entry, self.base) {
+                self.value = v;
+            }
+            self.typing = false;
+        }
+        self.word_size = size;
         self.value &= self.word_size.mask();
         if let Some(p) = self.pending.as_mut() {
             *p &= self.word_size.mask();
diff --git a/ui/app.slint b/ui/app.slint
index f95ab8a..0f8865c 100644
--- a/ui/app.slint
+++ b/ui/app.slint
@@ -3,17 +3,46 @@ export struct BitInfo {
     index: int,
 }
 
+export global UiStyle {
+    in-out property <int> size: 2;
+    in-out property <int> theme: 0;
+
+    in-out property <color> bg: #202020;
+    in-out property <color> surface: #2a2a2a;
+    in-out property <color> btn: #323232;
+    in-out property <color> btn-hover: #464646;
+    in-out property <color> digit: #3b3b3b;
+    in-out property <color> digit-hover: #505050;
+    in-out property <color> accent: #60cdff;
+    in-out property <color> accent-hover: #78d7ff;
+    in-out property <color> text: #ffffff;
+    in-out property <color> text-muted: #c8c8c8;
+    in-out property <color> text-dim: #9a9a9a;
+    in-out property <color> menu-active: #2f3a42;
+    in-out property <color> eq-text: #141414;
+    in-out property <color> border: #404040;
+
+    in-out property <length> btn-h: UiStyle.size == 1 ? 34px : (UiStyle.size == 3 ? 52px : 42px);
+    in-out property <length> btn-h-sm: UiStyle.size == 1 ? 28px : (UiStyle.size == 3 ? 40px : 32px);
+    in-out property <length> mem-h: UiStyle.size == 1 ? 26px : (UiStyle.size == 3 ? 38px : 32px);
+    in-out property <length> tab-h: UiStyle.size == 1 ? 26px : (UiStyle.size == 3 ? 34px : 30px);
+    in-out property <length> font-sm: UiStyle.size == 1 ? 12px : (UiStyle.size == 3 ? 15px : 13px);
+    in-out property <length> font-md: UiStyle.size == 1 ? 13px : (UiStyle.size == 3 ? 16px : 14px);
+    in-out property <length> font-digit: UiStyle.size == 1 ? 14px : (UiStyle.size == 3 ? 18px : 16px);
+    in-out property <length> font-eq: UiStyle.size == 1 ? 16px : (UiStyle.size == 3 ? 20px : 18px);
+}
+
 component BitCell inherits Rectangle {
     callback toggled();
     in property <bool> on;
     width: 14px;
     height: 16px;
     border-radius: 2px;
-    background: touch.has-hover ? #3a4550 : transparent;
+    background: touch.has-hover ? UiStyle.menu-active : transparent;
 
     Text {
         text: root.on ? "1" : "0";
-        color: root.on ? #60cdff : #6a6a6a;
+        color: root.on ? UiStyle.accent : UiStyle.text-dim;
         font-size: 10px;
         font-weight: 700;
         font-family: "Cascadia Mono, Consolas, DejaVu Sans Mono, monospace";
@@ -78,14 +107,14 @@ component BitLine inherits Rectangle {
 component MemBtn inherits Rectangle {
     callback clicked();
     in property <string> label;
-    height: 32px;
-    background: touch.has-hover ? #323232 : transparent;
+    height: UiStyle.mem-h;
+    background: touch.has-hover ? UiStyle.btn : transparent;
     border-radius: 4px;
 
     Text {
         text: root.label;
-        color: #c8c8c8;
-        font-size: 13px;
+        color: UiStyle.text-muted;
+        font-size: UiStyle.font-sm;
         horizontal-alignment: center;
         vertical-alignment: center;
     }
@@ -99,16 +128,16 @@ component FuncBtn inherits Rectangle {
     callback clicked();
     in property <string> label;
     in property <bool> enabled: true;
-    in property <length> min-h: 42px;
-    background: !root.enabled ? #2a2a2a : (touch.has-hover ? #464646 : #323232);
+    in property <length> min-h: UiStyle.btn-h;
+    background: !root.enabled ? UiStyle.surface : (touch.has-hover ? UiStyle.btn-hover : UiStyle.btn);
     border-radius: 4px;
     min-height: root.min-h;
     opacity: root.enabled ? 1.0 : 0.45;
 
     Text {
         text: root.label;
-        color: white;
-        font-size: 14px;
+        color: UiStyle.text;
+        font-size: UiStyle.font-md;
         horizontal-alignment: center;
         vertical-alignment: center;
     }
@@ -123,16 +152,16 @@ component DigitBtn inherits Rectangle {
     callback clicked();
     in property <string> label;
     in property <bool> enabled: true;
-    in property <length> min-h: 42px;
-    background: !root.enabled ? #2a2a2a : (touch.has-hover ? #505050 : #3b3b3b);
+    in property <length> min-h: UiStyle.btn-h;
+    background: !root.enabled ? UiStyle.surface : (touch.has-hover ? UiStyle.digit-hover : UiStyle.digit);
     border-radius: 4px;
     min-height: root.min-h;
     opacity: root.enabled ? 1.0 : 0.4;
 
     Text {
         text: root.label;
-        color: white;
-        font-size: 16px;
+        color: UiStyle.text;
+        font-size: UiStyle.font-digit;
         font-weight: 600;
         horizontal-alignment: center;
         vertical-alignment: center;
@@ -146,15 +175,15 @@ component DigitBtn inherits Rectangle {
 
 component EqBtn inherits Rectangle {
     callback clicked();
-    in property <length> min-h: 42px;
-    background: touch.has-hover ? #78d7ff : #60cdff;
+    in property <length> min-h: UiStyle.btn-h;
+    background: touch.has-hover ? UiStyle.accent-hover : UiStyle.accent;
     border-radius: 4px;
     min-height: root.min-h;
 
     Text {
         text: "=";
-        color: #141414;
-        font-size: 18px;
+        color: UiStyle.eq-text;
+        font-size: UiStyle.font-eq;
         font-weight: 700;
         horizontal-alignment: center;
         vertical-alignment: center;
@@ -170,11 +199,11 @@ component MenuRow inherits Rectangle {
     in property <string> label;
     in property <bool> active;
     height: 36px;
-    background: root.active ? #2f3a42 : (touch.has-hover ? #323232 : transparent);
+    background: root.active ? UiStyle.menu-active : (touch.has-hover ? UiStyle.btn : transparent);
 
     Text {
         text: root.label;
-        color: root.active ? #60cdff : #e0e0e0;
+        color: root.active ? UiStyle.accent : UiStyle.text;
         font-size: 14px;
         font-weight: root.active ? 700 : 500;
         vertical-alignment: center;
@@ -193,14 +222,14 @@ component ModeTab inherits Rectangle {
     callback clicked();
     in property <string> label;
     in property <bool> active;
-    height: 30px;
+    height: UiStyle.tab-h;
     border-radius: 4px;
-    background: root.active ? #3b3b3b : (touch.has-hover ? #2c2c2c : transparent);
+    background: root.active ? UiStyle.btn : (touch.has-hover ? UiStyle.surface : transparent);
 
     Text {
         text: root.label;
-        color: root.active ? #60cdff : #c8c8c8;
-        font-size: 13px;
+        color: root.active ? UiStyle.accent : UiStyle.text-muted;
+        font-size: UiStyle.font-sm;
         font-weight: root.active ? 700 : 500;
         horizontal-alignment: center;
         vertical-alignment: center;
@@ -325,12 +354,14 @@ export component AppWindow inherits Window {
     preferred-height: 640px;
     min-width: 380px;
     min-height: 520px;
-    background: #202020;
+    background: UiStyle.bg;
 
-    // 0=standard 1=engineering 2=programmer 3=convert 4=crc
+    // 0=standard 1=engineering 2=programmer 3=convert 4=crc 5=settings
     in-out property <int> mode: 0;
     in-out property <bool> menu-open: false;
     in property <string> mode-title: "Standard";
+    in property <int> cfg-button-size: 2;
+    in property <int> cfg-theme: 0;
 
     in property <string> display-text: "0";
     in property <string> expression-text: "";
@@ -414,7 +445,7 @@ export component AppWindow inherits Window {
                 width: 34px;
                 height: 34px;
                 border-radius: 4px;
-                background: menu-touch.has-hover || root.menu-open ? #3b3b3b : transparent;
+                background: menu-touch.has-hover || root.menu-open ? UiStyle.btn : transparent;
 
                 // Drawn icon — Unicode ☰ is missing in many Windows fonts.
                 VerticalLayout {
@@ -424,9 +455,9 @@ export component AppWindow inherits Window {
                     padding-right: 8px;
                     spacing: 4px;
 
-                    Rectangle { height: 2px; background: #e8e8e8; border-radius: 1px; }
-                    Rectangle { height: 2px; background: #e8e8e8; border-radius: 1px; }
-                    Rectangle { height: 2px; background: #e8e8e8; border-radius: 1px; }
+                    Rectangle { height: 2px; background: UiStyle.text; border-radius: 1px; }
+                    Rectangle { height: 2px; background: UiStyle.text; border-radius: 1px; }
+                    Rectangle { height: 2px; background: UiStyle.text; border-radius: 1px; }
                 }
 
                 menu-touch := TouchArea {
@@ -444,14 +475,14 @@ export component AppWindow inherits Window {
                     x: 0;
                     y: 38px;
                     width: 210px;
-                    height: 220px;
+                    height: 260px;
                     close-on-click: true;
 
                     Rectangle {
-                        background: #2a2a2a;
+                        background: UiStyle.surface;
                         border-radius: 6px;
                         border-width: 1px;
-                        border-color: #404040;
+                        border-color: UiStyle.border;
 
                         VerticalLayout {
                             padding: 6px;
@@ -502,6 +533,15 @@ export component AppWindow inherits Window {
                                     mode-menu.close();
                                 }
                             }
+                            MenuRow {
+                                label: "Settings";
+                                active: root.mode == 5;
+                                clicked => {
+                                    root.press("mode:settings");
+                                    root.menu-open = false;
+                                    mode-menu.close();
+                                }
+                            }
                         }
                     }
                 }
@@ -509,7 +549,7 @@ export component AppWindow inherits Window {
 
             Text {
                 text: root.mode-title;
-                color: white;
+                color: UiStyle.text;
                 font-size: 18px;
                 font-weight: 700;
                 vertical-alignment: center;
@@ -521,7 +561,7 @@ export component AppWindow inherits Window {
             height: 18px;
             Text {
                 text: root.has-memory && (root.mode == 0 || root.mode == 1) ? "M" : "";
-                color: #b4b4b4;
+                color: UiStyle.text-muted;
                 font-size: 12px;
                 horizontal-alignment: left;
                 vertical-alignment: center;
@@ -529,13 +569,13 @@ export component AppWindow inherits Window {
             }
             Text {
                 text: root.mode == 2 ? root.word-size-label : "";
-                color: #60cdff;
+                color: UiStyle.accent;
                 font-size: 11px;
                 vertical-alignment: center;
             }
             Text {
                 text: root.expression-text;
-                color: #aaaaaa;
+                color: UiStyle.text-dim;
                 font-size: 13px;
                 horizontal-alignment: right;
                 vertical-alignment: center;
@@ -544,7 +584,7 @@ export component AppWindow inherits Window {
 
         if root.mode == 0 || root.mode == 1 || root.mode == 2: Text {
             text: root.display-text;
-            color: white;
+            color: UiStyle.text;
             font-size: root.mode == 2 ? 28px : 34px;
             font-weight: 700;
             horizontal-alignment: right;
@@ -1141,85 +1181,85 @@ export component AppWindow inherits Window {
             spacing: 4px;
             Row {
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "2nd●" : "2nd";
                     clicked => { root.press("eng:2nd"); }
                 }
-                FuncBtn { min-h: 32px; label: "π"; clicked => { root.press("eng:pi"); } }
-                FuncBtn { min-h: 32px; label: "e"; clicked => { root.press("eng:e"); } }
-                FuncBtn { min-h: 32px; label: "C"; clicked => { root.press("C"); } }
-                FuncBtn { min-h: 32px; label: "⌫"; clicked => { root.press("BS"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "π"; clicked => { root.press("eng:pi"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "e"; clicked => { root.press("eng:e"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "C"; clicked => { root.press("C"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "⌫"; clicked => { root.press("BS"); } }
             }
             Row {
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "sin⁻¹" : "sin";
                     clicked => { root.press(root.eng-second ? "eng:asin" : "eng:sin"); }
                 }
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "cos⁻¹" : "cos";
                     clicked => { root.press(root.eng-second ? "eng:acos" : "eng:cos"); }
                 }
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "tan⁻¹" : "tan";
                     clicked => { root.press(root.eng-second ? "eng:atan" : "eng:tan"); }
                 }
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "³√x" : "√x";
                     clicked => { root.press(root.eng-second ? "eng:cbrt" : "eng:sqrt"); }
                 }
-                FuncBtn { min-h: 32px; label: "÷"; clicked => { root.press("/"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "÷"; clicked => { root.press("/"); } }
             }
             Row {
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "x³" : "x²";
                     clicked => { root.press(root.eng-second ? "eng:cube" : "eng:sq"); }
                 }
-                FuncBtn { min-h: 32px; label: "1/x"; clicked => { root.press("eng:inv"); } }
-                FuncBtn { min-h: 32px; label: "|x|"; clicked => { root.press("eng:abs"); } }
-                FuncBtn { min-h: 32px; label: "n!"; clicked => { root.press("eng:fact"); } }
-                FuncBtn { min-h: 32px; label: "×"; clicked => { root.press("*"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "1/x"; clicked => { root.press("eng:inv"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "|x|"; clicked => { root.press("eng:abs"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "n!"; clicked => { root.press("eng:fact"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "×"; clicked => { root.press("*"); } }
             }
             Row {
-                FuncBtn { min-h: 32px; label: "x^y"; clicked => { root.press("^"); } }
-                FuncBtn { min-h: 32px; label: "("; clicked => { root.press("("); } }
-                FuncBtn { min-h: 32px; label: ")"; clicked => { root.press(")"); } }
-                FuncBtn { min-h: 32px; label: "CE"; clicked => { root.press("CE"); } }
-                FuncBtn { min-h: 32px; label: "−"; clicked => { root.press("-"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "x^y"; clicked => { root.press("^"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "("; clicked => { root.press("("); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: ")"; clicked => { root.press(")"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "CE"; clicked => { root.press("CE"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "−"; clicked => { root.press("-"); } }
             }
             Row {
                 FuncBtn {
-                    min-h: 32px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.eng-second ? "eˣ" : "10ˣ";
                     clicked => { root.press(root.eng-second ? "eng:exp" : "eng:tenpow"); }
                 }
-                DigitBtn { min-h: 32px; label: "7"; clicked => { root.press("7"); } }
-                DigitBtn { min-h: 32px; label: "8"; clicked => { root.press("8"); } }
-                DigitBtn { min-h: 32px; label: "9"; clicked => { root.press("9"); } }
-                FuncBtn { min-h: 32px; label: "+"; clicked => { root.press("+"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "7"; clicked => { root.press("7"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "8"; clicked => { root.press("8"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "9"; clicked => { root.press("9"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "+"; clicked => { root.press("+"); } }
             }
             Row {
-                FuncBtn { min-h: 32px; label: "log"; clicked => { root.press("eng:log"); } }
-                DigitBtn { min-h: 32px; label: "4"; clicked => { root.press("4"); } }
-                DigitBtn { min-h: 32px; label: "5"; clicked => { root.press("5"); } }
-                DigitBtn { min-h: 32px; label: "6"; clicked => { root.press("6"); } }
-                DigitBtn { min-h: 32px; label: "±"; clicked => { root.press("neg"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "log"; clicked => { root.press("eng:log"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "4"; clicked => { root.press("4"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "5"; clicked => { root.press("5"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "6"; clicked => { root.press("6"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "±"; clicked => { root.press("neg"); } }
             }
             Row {
-                FuncBtn { min-h: 32px; label: "ln"; clicked => { root.press("eng:ln"); } }
-                DigitBtn { min-h: 32px; label: "1"; clicked => { root.press("1"); } }
-                DigitBtn { min-h: 32px; label: "2"; clicked => { root.press("2"); } }
-                DigitBtn { min-h: 32px; label: "3"; clicked => { root.press("3"); } }
-                EqBtn { min-h: 32px; clicked => { root.press("="); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "ln"; clicked => { root.press("eng:ln"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "1"; clicked => { root.press("1"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "2"; clicked => { root.press("2"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "3"; clicked => { root.press("3"); } }
+                EqBtn { min-h: UiStyle.btn-h-sm; clicked => { root.press("="); } }
             }
             Row {
-                DigitBtn { min-h: 32px; label: "0"; clicked => { root.press("0"); } }
-                DigitBtn { min-h: 32px; label: "."; clicked => { root.press("."); } }
-                FuncBtn { min-h: 32px; label: "exp"; clicked => { root.press("eng:exp"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "0"; clicked => { root.press("0"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "."; clicked => { root.press("."); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "exp"; clicked => { root.press("eng:exp"); } }
                 Rectangle { min-height: 32px; background: transparent; }
                 Rectangle { min-height: 32px; background: transparent; }
             }
@@ -1295,62 +1335,136 @@ export component AppWindow inherits Window {
         if root.mode == 2: GridLayout {
             spacing: 4px;
             Row {
-                FuncBtn { min-h: 34px; label: root.word-size-label; clicked => { root.press("word"); } }
-                FuncBtn { min-h: 34px; label: "CE"; clicked => { root.press("CE"); } }
-                FuncBtn { min-h: 34px; label: "C"; clicked => { root.press("clear"); } }
-                FuncBtn { min-h: 34px; label: "⌫"; clicked => { root.press("BS"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: root.word-size-label; clicked => { root.press("word"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "CE"; clicked => { root.press("CE"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "C"; clicked => { root.press("clear"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "⌫"; clicked => { root.press("BS"); } }
             }
             Row {
-                FuncBtn { min-h: 34px; label: "AND"; clicked => { root.press("AND"); } }
-                FuncBtn { min-h: 34px; label: "OR"; clicked => { root.press("OR"); } }
-                FuncBtn { min-h: 34px; label: "NOT"; clicked => { root.press("NOT"); } }
-                FuncBtn { min-h: 34px; label: "NAND"; clicked => { root.press("NAND"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "AND"; clicked => { root.press("AND"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "OR"; clicked => { root.press("OR"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "NOT"; clicked => { root.press("NOT"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "NAND"; clicked => { root.press("NAND"); } }
             }
             Row {
-                FuncBtn { min-h: 34px; label: "NOR"; clicked => { root.press("NOR"); } }
-                FuncBtn { min-h: 34px; label: "XOR"; clicked => { root.press("XOR"); } }
-                FuncBtn { min-h: 34px; label: "Lsh"; clicked => { root.press("Lsh"); } }
-                FuncBtn { min-h: 34px; label: "Rsh"; clicked => { root.press("Rsh"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "NOR"; clicked => { root.press("NOR"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "XOR"; clicked => { root.press("XOR"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "Lsh"; clicked => { root.press("Lsh"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "Rsh"; clicked => { root.press("Rsh"); } }
             }
             Row {
-                DigitBtn { min-h: 34px; label: "A"; enabled: root.allow-a; clicked => { root.press("A"); } }
-                DigitBtn { min-h: 34px; label: "B"; enabled: root.allow-a; clicked => { root.press("B"); } }
-                DigitBtn { min-h: 34px; label: "C"; enabled: root.allow-a; clicked => { root.press("C"); } }
-                FuncBtn { min-h: 34px; label: "÷"; clicked => { root.press("/"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "A"; enabled: root.allow-a; clicked => { root.press("A"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "B"; enabled: root.allow-a; clicked => { root.press("B"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "C"; enabled: root.allow-a; clicked => { root.press("C"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "÷"; clicked => { root.press("/"); } }
             }
             Row {
-                DigitBtn { min-h: 34px; label: "D"; enabled: root.allow-a; clicked => { root.press("D"); } }
-                DigitBtn { min-h: 34px; label: "E"; enabled: root.allow-a; clicked => { root.press("E"); } }
-                DigitBtn { min-h: 34px; label: "F"; enabled: root.allow-a; clicked => { root.press("F"); } }
-                FuncBtn { min-h: 34px; label: "×"; clicked => { root.press("*"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "D"; enabled: root.allow-a; clicked => { root.press("D"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "E"; enabled: root.allow-a; clicked => { root.press("E"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "F"; enabled: root.allow-a; clicked => { root.press("F"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "×"; clicked => { root.press("*"); } }
             }
             Row {
-                DigitBtn { min-h: 34px; label: "7"; enabled: root.allow-2; clicked => { root.press("7"); } }
-                DigitBtn { min-h: 34px; label: "8"; enabled: root.allow-8; clicked => { root.press("8"); } }
-                DigitBtn { min-h: 34px; label: "9"; enabled: root.allow-8; clicked => { root.press("9"); } }
-                FuncBtn { min-h: 34px; label: "−"; clicked => { root.press("-"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "7"; enabled: root.allow-2; clicked => { root.press("7"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "8"; enabled: root.allow-8; clicked => { root.press("8"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "9"; enabled: root.allow-8; clicked => { root.press("9"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "−"; clicked => { root.press("-"); } }
             }
             Row {
-                DigitBtn { min-h: 34px; label: "4"; enabled: root.allow-2; clicked => { root.press("4"); } }
-                DigitBtn { min-h: 34px; label: "5"; enabled: root.allow-2; clicked => { root.press("5"); } }
-                DigitBtn { min-h: 34px; label: "6"; enabled: root.allow-2; clicked => { root.press("6"); } }
-                FuncBtn { min-h: 34px; label: "+"; clicked => { root.press("+"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "4"; enabled: root.allow-2; clicked => { root.press("4"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "5"; enabled: root.allow-2; clicked => { root.press("5"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "6"; enabled: root.allow-2; clicked => { root.press("6"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "+"; clicked => { root.press("+"); } }
             }
             Row {
-                DigitBtn { min-h: 34px; label: "1"; clicked => { root.press("1"); } }
-                DigitBtn { min-h: 34px; label: "2"; enabled: root.active-base != 3; clicked => { root.press("2"); } }
-                DigitBtn { min-h: 34px; label: "3"; enabled: root.allow-2; clicked => { root.press("3"); } }
-                FuncBtn { min-h: 34px; label: "%"; clicked => { root.press("%"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "1"; clicked => { root.press("1"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "2"; enabled: root.active-base != 3; clicked => { root.press("2"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "3"; enabled: root.allow-2; clicked => { root.press("3"); } }
+                FuncBtn { min-h: UiStyle.btn-h-sm; label: "%"; clicked => { root.press("%"); } }
             }
             Row {
-                DigitBtn { min-h: 34px; label: "±"; clicked => { root.press("neg"); } }
-                DigitBtn { min-h: 34px; label: "0"; clicked => { root.press("0"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "±"; clicked => { root.press("neg"); } }
+                DigitBtn { min-h: UiStyle.btn-h-sm; label: "0"; clicked => { root.press("0"); } }
                 FuncBtn {
-                    min-h: 34px;
+                    min-h: UiStyle.btn-h-sm;
                     label: root.show-bits ? "Bits●" : "Bits";
                     clicked => { root.press("bits"); }
                 }
-                EqBtn { min-h: 34px; clicked => { root.press("="); } }
+                EqBtn { min-h: UiStyle.btn-h-sm; clicked => { root.press("="); } }
+            }
+        }
+
+        if root.mode == 5: VerticalLayout {
+            spacing: 14px;
+            padding-top: 8px;
+
+            Text {
+                text: "Appearance";
+                color: UiStyle.accent;
+                font-size: 16px;
+                font-weight: 700;
+            }
+
+            Text {
+                text: "Button size";
+                color: UiStyle.text-dim;
+                font-size: 12px;
+            }
+            HorizontalLayout {
+                spacing: 6px;
+                ModeTab {
+                    label: "1 Compact";
+                    active: root.cfg-button-size == 1;
+                    clicked => { root.press("cfg:size:1"); }
+                }
+                ModeTab {
+                    label: "2 Normal";
+                    active: root.cfg-button-size == 2;
+                    clicked => { root.press("cfg:size:2"); }
+                }
+                ModeTab {
+                    label: "3 Large";
+                    active: root.cfg-button-size == 3;
+                    clicked => { root.press("cfg:size:3"); }
+                }
+            }
+
+            Text {
+                text: "Theme";
+                color: UiStyle.text-dim;
+                font-size: 12px;
+            }
+            HorizontalLayout {
+                spacing: 6px;
+                ModeTab {
+                    label: "Dark";
+                    active: root.cfg-theme == 0;
+                    clicked => { root.press("cfg:theme:0"); }
+                }
+                ModeTab {
+                    label: "Light";
+                    active: root.cfg-theme == 1;
+                    clicked => { root.press("cfg:theme:1"); }
+                }
+                ModeTab {
+                    label: "Blue";
+                    active: root.cfg-theme == 2;
+                    clicked => { root.press("cfg:theme:2"); }
+                }
+            }
+
+            Text {
+                text: "Settings are saved automatically.";
+                color: UiStyle.text-dim;
+                font-size: 12px;
+            }
+
+            HorizontalLayout {
+                spacing: 6px;
+                FuncBtn {
+                    label: "Back";
+                    clicked => { root.press("mode:std"); }
+                }
             }
         }
     }