diff --git a/config.json b/config.json
index 9ceb643..ff58122 100644
--- a/config.json
+++ b/config.json
@@ -1,62 +1,72 @@
-{
-    "ocr_regions": [
-        {
-            "name": "lap",
-            "x": 2300,
-            "y": 46,
-            "width": 140,
-            "height": 90
-        },
-        {
-            "name": "health",
-            "x": 90,
-            "y": 1364,
-            "width": 52,
-            "height": 24
-        },
-        {
-            "name": "gas",
-            "x": 208,
-            "y": 1364,
-            "width": 52,
-            "height": 24
-        },
-        {
-            "name": "tyres",
-            "x": 325,
-            "y": 1364,
-            "width": 52,
-            "height": 24
-        },
-        {
-            "name": "best",
-            "x": 2325,
-            "y": 169,
-            "width": 183,
-            "height": 43
-        },
-        {
-            "name": "lap_time",
-            "x": 2325,
-            "y": 222,
-            "width": 183,
-            "height": 43
-        }
-    ],
-    "track_region": {
-        "name": "track",
-        "x": 2020,
-        "y": 1030,
-        "width": 540,
-        "height": 410,
-        "threshold": 0.85
-    },
-    "penalty_orange_region": {
-        "name": "penalty",
-        "x": 989,
-        "y": 117,
-        "width": 30,
-        "height": 30
-    },
-    "track_recognition_threshold": 10
+{
+  "ocr_regions": [
+    {
+      "name": "lap",
+      "x": 2300,
+      "y": 46,
+      "width": 140,
+      "height": 90,
+      "threshold": null,
+      "use_ocr_cache": null
+    },
+    {
+      "name": "health",
+      "x": 90,
+      "y": 1364,
+      "width": 52,
+      "height": 24,
+      "threshold": null,
+      "use_ocr_cache": null
+    },
+    {
+      "name": "gas",
+      "x": 208,
+      "y": 1364,
+      "width": 52,
+      "height": 24,
+      "threshold": null,
+      "use_ocr_cache": null
+    },
+    {
+      "name": "tyres",
+      "x": 325,
+      "y": 1364,
+      "width": 52,
+      "height": 24,
+      "threshold": null,
+      "use_ocr_cache": null
+    },
+    {
+      "name": "best",
+      "x": 2325,
+      "y": 169,
+      "width": 183,
+      "height": 43,
+      "threshold": null,
+      "use_ocr_cache": null
+    },
+    {
+      "name": "lap_time",
+      "x": 2325,
+      "y": 222,
+      "width": 183,
+      "height": 43,
+      "threshold": null,
+      "use_ocr_cache": null
+    }
+  ],
+  "track_region": {
+    "name": "track",
+    "x": 2020,
+    "y": 1030,
+    "width": 540,
+    "height": 410,
+    "threshold": 0.85,
+    "use_ocr_cache": null
+  },
+  "ocr_interval_ms": 500,
+  "track_recognition_threshold": 10,
+  "dump_frame_fraction": null,
+  "light_mode": false,
+  "font_scale": 1.3
 }
\ No newline at end of file
diff --git a/src/analysis.rs b/src/analysis.rs
index 72a800a..945b02c 100644
--- a/src/analysis.rs
+++ b/src/analysis.rs
@@ -145,7 +145,7 @@ fn add_saved_frame(
             image: retained,
             rgb_image: extracted,
             img_hash: hash,
-            recognized_text: ocr_results.get(&region.name).cloned(),
+            recognized_text: ocr_results.get(&region.name).cloned().unwrap_or_default(),
         },
     );
 }
@@ -224,7 +224,7 @@ pub fn run_control_loop(state: SharedAppState) {
         if let Err(e) = run_loop_once(&mut capturer, &state) {
             eprintln!("Error in control loop: {:?}", e)
         }
-        let interval = state.lock().unwrap().config.ocr_interval_ms.unwrap_or(500);
+        let interval = state.lock().unwrap().config.ocr_interval_ms;
         thread::sleep(Duration::from_millis(interval));
     }
 }
diff --git a/src/config.rs b/src/config.rs
index 7427643..3140029 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,23 +1,55 @@
-use std::path::PathBuf;
+use std::{path::PathBuf, sync::Arc};
 
 use anyhow::Result;
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 
 use crate::image_processing::Region;
 
+fn default_track_recognition_threshold() -> u32 {
+    10
+}
+fn default_ocr_interval_ms() -> u64 {
+    500
+}
+fn default_font_scale() -> f32 {
+    1.0
+}
+
 #[derive(Default, Serialize, Deserialize, Clone)]
 pub struct Config {
     pub ocr_regions: Vec<Region>,
     pub track_region: Option<Region>,
-    pub ocr_interval_ms: Option<u64>,
-    pub track_recognition_threshold: Option<u32>,
+
+    #[serde(default = "default_ocr_interval_ms")]
+    pub ocr_interval_ms: u64,
+
+    #[serde(default = "default_track_recognition_threshold")]
+    pub track_recognition_threshold: u32,
+
     pub dump_frame_fraction: Option<f64>,
+
+    #[serde(default = "Default::default")]
+    pub light_mode: bool,
+
+    #[serde(default = "default_font_scale")]
+    pub font_scale: f32,
 }
 
 impl Config {
     pub fn load() -> Result<Self> {
         load_config_or_make_default("config.json", include_str!("configs/config.default.json"))
     }
+
+    pub fn update_and_save<F: Fn(&mut Self)>(
+        self: &mut Arc<Self>,
+        update_fn: F,
+    ) -> Result<()> {
+        let mut config = (**self).clone();
+        update_fn(&mut config);
+        save_json_config("config.json", &config)?;
+        *self = Arc::new(config);
+        Ok(())
+    }
 }
 
 pub fn load_config_or_make_default<T: DeserializeOwned>(path: &str, default: &str) -> Result<T> {
diff --git a/src/learned_tracks.rs b/src/learned_tracks.rs
index 197e925..5a12e98 100644
--- a/src/learned_tracks.rs
+++ b/src/learned_tracks.rs
@@ -28,8 +28,7 @@ impl LearnedTracks {
         for (learned_hash_b64, learned_track) in &self.learned_tracks {
             let learned_hash: ImageHash<Vec<u8>> = ImageHash::from_base64(learned_hash_b64).ok()?;
             let current_hash: ImageHash<Vec<u8>> = ImageHash::from_base64(hash).ok()?;
-            if current_hash.dist(&learned_hash) <= config.track_recognition_threshold.unwrap_or(10)
-            {
+            if current_hash.dist(&learned_hash) <= config.track_recognition_threshold {
                 return Some(learned_track.to_owned());
             }
         }
diff --git a/src/main.rs b/src/main.rs
index ca28135..0d321d1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -23,7 +23,7 @@ use std::{
 use analysis::save_frames_from;
 use config::Config;
 use eframe::{
-    egui::{self, Ui, Visuals},
+    egui::{self, FontTweak, Ui, Visuals},
     emath::Vec2,
     epaint::Color32,
 };
@@ -238,20 +238,22 @@ fn show_race_state(
     });
 }
 
-fn show_debug_frames(ui: &mut Ui, debug_frames: &mut HashMap<String, DebugOcrFrame>) {
+fn show_debug_frames(
+    ui: &mut Ui,
+    ocr_db: &OcrDatabase,
+    debug_frames: &mut HashMap<String, DebugOcrFrame>,
+) {
     for (name, debug_image) in debug_frames.iter_mut() {
         ui.label(name);
-        if let Some(text) = &debug_image.recognized_text {
-            ui.label(text);
-        }
-        if ui
-            .button(&debug_image.img_hash)
-            .on_hover_text("Copy")
-            .clicked()
-        {
-            ui.output().copied_text = debug_image.img_hash.clone();
-        }
+        ui.text_edit_singleline(&mut debug_image.recognized_text);
         debug_image.image.show_max_size(ui, Vec2::new(300.0, 300.0));
+
+        if ui.button("Learn OCR").clicked() {
+            let hashes = ocr::compute_box_hashes(&debug_image.rgb_image);
+            ocr_db
+                .learn_phrase(&hashes, &debug_image.recognized_text)
+                .unwrap();
+        }
         ui.separator();
     }
 }
@@ -298,6 +300,20 @@ fn show_combo_box(ui: &mut Ui, name: &str, label: &str, options: &[String], valu
 impl eframe::App for AppUi {
     fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
         let mut state = self.state.lock().unwrap();
+        if state.config.light_mode {
+            ctx.set_visuals(Visuals::light());
+        } else {
+            ctx.set_visuals(Visuals::dark());
+        }
+        let mut fonts = egui::FontDefinitions::default();
+        for font in fonts.font_data.values_mut() {
+            *font = font.clone().tweak(FontTweak {
+                scale: state.config.font_scale,
+                ..Default::default()
+            });
+        }
+        ctx.set_fonts(fonts);
+
         let ocr_db = state.ocr_db.clone();
 
         let mut debug_lap_window = self.ui_state.debug_lap.is_some();
@@ -310,7 +326,7 @@ impl eframe::App for AppUi {
                         .show_max_size(ui, Vec2::new(800.0, 600.0));
                     ui.separator();
                     if let Some(debug_lap) = &mut self.ui_state.debug_lap {
-                        show_debug_frames(ui, &mut debug_lap.debug_regions);
+                        show_debug_frames(ui, &ocr_db, &mut debug_lap.debug_regions);
                     }
                     show_config_controls(ui, &mut self.ui_state, state.deref_mut());
                 }
@@ -320,7 +336,6 @@ impl eframe::App for AppUi {
             self.ui_state.debug_lap = None;
         }
 
-        ctx.set_visuals(Visuals::dark());
         egui::SidePanel::left("frame").show(ctx, |ui| {
             if let Some(frame) = &state.last_frame {
                 ui.heading("Race data");
@@ -349,7 +364,7 @@ impl eframe::App for AppUi {
                     ui.separator();
                     ui.heading("Strategy");
                     if let Some(tyre_wear) = race.tyre_wear() {
-                        ui.heading(&format!("p50 Tyre Wear: {}", tyre_wear));
+                        ui.label(&format!("Median Tyre Wear: {}", tyre_wear));
                         if let Some(tyres) = frame.tyres {
                             ui.label(&format!(
                                 "Out of tires in {:.1} lap(s)",
@@ -358,7 +373,7 @@ impl eframe::App for AppUi {
                         }
                     }
                     if let Some(gas_wear) = race.gas_per_lap() {
-                        ui.heading(&format!("p50 Gas Wear: {}", gas_wear));
+                        ui.label(&format!("Median Gas Wear: {}", gas_wear));
                         if let Some(gas) = frame.gas {
                             ui.label(&format!(
                                 "Out of gas in {:.1} lap(s)",
@@ -368,20 +383,55 @@ impl eframe::App for AppUi {
                     }
                 }
             }
-
-            ui.separator();
-            ui.checkbox(&mut state.debug_frames, "Debug OCR regions");
-            if state.config.dump_frame_fraction.is_some() {
-                ui.checkbox(
-                    &mut state.should_sample_ocr_data,
-                    "Dump OCR training frames",
-                );
-            }
         });
         egui::CentralPanel::default().show(ctx, |ui| {
+            egui::menu::bar(ui, |ui| {
+                egui::menu::menu_button(ui, "Control", |ui| {
+                    if ui.button("Debug OCR regions").clicked() {
+                        state.debug_frames = !state.debug_frames;
+                    }
+                    if state.config.dump_frame_fraction.is_some() {
+                        let button_text = if state.should_sample_ocr_data {
+                            "Stop OCR training dump"
+                        } else {
+                            "Dump OCR training data"
+                        };
+                        if ui.button(button_text).clicked() {
+                            state.should_sample_ocr_data = !state.should_sample_ocr_data;
+                        }
+                    }
+                    show_config_controls(ui, &mut self.ui_state, &mut state);
+                });
+
+                egui::menu::menu_button(ui, "Preferences", |ui| {
+                    let light_mode_text = if state.config.light_mode {
+                        "☀ light mode"
+                    } else {
+                        "☀ dark mode"
+                    };
+                    if ui.button(light_mode_text).clicked() {
+                        state
+                            .config
+                            .update_and_save(|config| config.light_mode = !config.light_mode)
+                            .unwrap();
+                    }
+
+                    let mut font_scale = state.config.font_scale;
+                    ui.add(egui::Slider::new(&mut font_scale, 0.1..=5.0).text("Font scale"));
+                    if font_scale != state.config.font_scale {
+                        state
+                            .config
+                            .update_and_save(|config| {
+                                config.font_scale = font_scale;
+                            })
+                            .unwrap();
+                    }
+                });
+            });
+            ui.separator();
+
             egui::ScrollArea::vertical().show(ui, |ui| {
                 let config = state.config.clone();
-                let _learned_tracks = state.learned_tracks.clone();
                 if let Some(race) = &mut state.current_race {
                     ui.heading(&format!("Current Race: {}", race.name()));
                     show_race_state(
@@ -465,8 +515,8 @@ impl eframe::App for AppUi {
         if state.debug_frames {
             egui::SidePanel::right("screenshots").show(ctx, |ui| {
                 egui::ScrollArea::vertical().show(ui, |ui| {
-                    show_debug_frames(ui, &mut state.saved_frames);
-                    show_config_controls(ui, &mut self.ui_state, state.deref_mut());
+                    let ocr_db = state.ocr_db.clone();
+                    show_debug_frames(ui, ocr_db.as_ref(), &mut state.saved_frames);
                 });
             });
         }
diff --git a/src/state.rs b/src/state.rs
index 590a99d..22ead1f 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -128,7 +128,7 @@ pub struct DebugOcrFrame {
     pub image: RetainedImage,
     pub rgb_image: RgbImage,
     pub img_hash: String,
-    pub recognized_text: Option<String>,
+    pub recognized_text: String,
 }
 
 #[derive(Default)]