diff --git a/README.md b/README.md
index 8063497b..e60e7b48 100644
--- a/README.md
+++ b/README.md
@@ -163,6 +163,8 @@ systemctl enable leads_vec
 python -m leads_vec -t path/to/the/theme.json run
 ```
 
+To learn about themes, read [Color and Themes](https://customtkinter.tomschimansky.com/documentation/color).
+
 ##### Magnify Font Sizes
 
 ```shell
@@ -265,6 +267,7 @@ Note that a purely empty file could cause an error.
 | `height`            | `int`   | Window height                                             | Main         | `480`         |
 | `fullscreen`        | `bool`  | `True`: auto maximize; `False`: window mode               | Main         | `False`       |
 | `no_title_bar`      | `bool`  | `True`: no title bar; `False`: default title bar          | Main         | `False`       |
+| `theme_mode`        | `bool`  | `"system"`, `"light"`, `"dark`"                           | Main         | `False`       |
 | `manual_mode`       | `bool`  | `True`: hide control system; `False`: show control system | Main         | `False`       |
 | `refresh_rate`      | `int`   | GUI frame per second                                      | Main         | `30`          |
 | `m_ratio`           | `float` | Meter widget size ratio                                   | Main         | `0.7`         |
diff --git a/leads/config/template.py b/leads/config/template.py
index 039dd8f9..3cb68ff6 100644
--- a/leads/config/template.py
+++ b/leads/config/template.py
@@ -1,5 +1,5 @@
 from json import dumps as _dumps
-from typing import Any as _Any, override as _override
+from typing import Any as _Any, override as _override, Literal as _Literal
 
 from leads.data import Serializable
 
@@ -9,11 +9,11 @@ def __init__(self, base: dict[str, _Any]) -> None:
         """
         All custom attributes should be public (not named after "_").
         Writable attributes should start with "w_" such as "w_debug_level".
-        :param base: base dictionary
+        :param base: the base dictionary
         """
         self._d: dict[str, _Any] = base
         self._frozen: bool = False
-        self.w_debug_level: str = "DEBUG"
+        self.w_debug_level: _Literal["DEBUG", "INFO", "WARN", "ERROR"] = "DEBUG"
         self.data_seq_size: int = 100
         self.num_laps_timed: int = 3
         self.data_dir: str = "data"
@@ -60,8 +60,8 @@ def _writable(self, name: str) -> bool:
     def set(self, name: str, value: _Any) -> None:
         """
         Set the value with a given name in the dictionary.
-        :param name: dictionary key
-        :param value: value to set
+        :param name: the dictionary key
+        :param value: the value to set
         """
         if self._writable(name):
             self._d[name] = value
@@ -70,8 +70,8 @@ def set(self, name: str, value: _Any) -> None:
     def get(self, name: str, default: _Any | None = None) -> _Any | None:
         """
         Get the value of a given name from the dictionary.
-        :param name: dictionary key
-        :param default: default value if the value does not exist
+        :param name: the dictionary key
+        :param default: the default value if the value does not exist
         :return: the value if it exists or else the default value
         """
         return self._d.get(name, default)
diff --git a/leads_gui/config.py b/leads_gui/config.py
index 99dafbc5..683a675e 100644
--- a/leads_gui/config.py
+++ b/leads_gui/config.py
@@ -1,4 +1,4 @@
-from typing import Any as _Any
+from typing import Any as _Any, Literal as _Literal
 
 from leads import ConfigTemplate as _ConfigTemplate
 
@@ -9,6 +9,7 @@ def __init__(self, base: dict[str, _Any]) -> None:
         self.height: int = 480
         self.fullscreen: bool = False
         self.no_title_bar: bool = False
+        self.theme_mode: _Literal["system", "light", "dark"] = "system"
         self.manual_mode: bool = False
         self.refresh_rate: int = 30
         self.m_ratio: float = .7
diff --git a/leads_gui/prototype.py b/leads_gui/prototype.py
index cc875703..437c067a 100644
--- a/leads_gui/prototype.py
+++ b/leads_gui/prototype.py
@@ -1,9 +1,11 @@
 from tkinter import Misc as _Misc, Event as _Event
-from typing import Callable as _Callable, Self as _Self, TypeVar as _TypeVar, Generic as _Generic, Any as _Any
+from typing import Callable as _Callable, Self as _Self, TypeVar as _TypeVar, Generic as _Generic, Any as _Any, \
+    Literal as _Literal
 
 from PIL import ImageTk as _ImageTk
 from customtkinter import CTk as _CTk, CTkCanvas as _CTkCanvas, get_appearance_mode as _get_appearance_mode, \
-    ThemeManager as _ThemeManager, Variable as _Variable, ScalingTracker as _ScalingTracker
+    ThemeManager as _ThemeManager, Variable as _Variable, ScalingTracker as _ScalingTracker, \
+    set_appearance_mode as _set_appearance_mode
 from numpy import lcm as _lcm
 
 from leads import require_config as _require_config
@@ -190,12 +192,14 @@ def __init__(self,
                  on_refresh: _Callable[[_Self], None] = lambda _: None,
                  title: str = "LEADS",
                  fullscreen: bool = True,
-                 no_title_bar: bool = True) -> None:
+                 no_title_bar: bool = True,
+                 theme_mode: _Literal["system", "light", "dark"] = "system") -> None:
         self._root: _CTk = _CTk()
         self._root.title(title)
         self._root.wm_iconbitmap()
         self._root.iconphoto(True, _ImageTk.PhotoImage(file=f"{_ASSETS_PATH}/logo.png"))
         self._root.overrideredirect(no_title_bar)
+        _set_appearance_mode(theme_mode)
         sw, sh = self._root.winfo_screenwidth(), self._root.winfo_screenheight()
         self._width: int = sw if fullscreen else width
         self._height: int = sh if fullscreen else height