diff --git a/pyproject.toml b/pyproject.toml
index 4a2b7ffa..cd993b79 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -48,9 +48,11 @@ mark-parentheses = false
 extend-ignore-names = ['allKeys',
                        'addItem',
                        'addItems',
+                       'changeEvent',
                        'closeEvent',
                        'columnCount',
                        'createEditor',
+                       'drawComplexControl',
                        'expandingDirections',
                        'eventFilter',
                        'hasHeightForWidth',
diff --git a/rascal2/app.py b/rascal2/app.py
index 7fddba1e..68836ae7 100644
--- a/rascal2/app.py
+++ b/rascal2/app.py
@@ -1,12 +1,11 @@
 import logging
 import multiprocessing
-import re
-from contextlib import suppress
 
 from PyQt6 import QtWidgets
 
 from rascal2.config import MatlabHelper, handle_scaling, setup_logging
-from rascal2.paths import IMAGES_PATH, STATIC_PATH
+from rascal2.settings import get_colour_scheme
+from rascal2.theme import THEMES, set_stylesheet
 from rascal2.ui.view import MainWindowView
 
 
@@ -19,25 +18,19 @@ def ui_execute(splash):
         QApplication exit code
     """
     handle_scaling()
-    QtWidgets.QApplication.setStyle("Fusion")
     app = QtWidgets.QApplication.instance()
-    with suppress(FileNotFoundError), open(STATIC_PATH / "style.css") as stylesheet:
-        palette = app.palette()
-        replacements = {
-            "@Path": IMAGES_PATH.as_posix(),
-            "@Window": palette.window().color().name(),
-            "@Highlight": palette.highlight().color().name(),
-            "@Midlight": palette.midlight().color().name(),
-            "@Text": palette.text().color().name(),
-        }
-        style = re.sub("|".join(replacements), lambda x: replacements[x.group(0)], stylesheet.read())
-        app.setStyleSheet(style)
+    app.setStyle("Fusion")
+    app.installEventFilter(THEMES)
+    app.styleHints().setColorScheme(get_colour_scheme())
+    set_stylesheet(app)
 
     window = MainWindowView()
     window.show()
     splash.finish(window)
 
-    return app.exec()
+    exit_code = app.exec()
+    app.removeEventFilter(THEMES)
+    return exit_code
 
 
 def start_app(splash):
diff --git a/rascal2/dialogs/settings_dialog.py b/rascal2/dialogs/settings_dialog.py
index b946e8e4..ddd3ac7a 100644
--- a/rascal2/dialogs/settings_dialog.py
+++ b/rascal2/dialogs/settings_dialog.py
@@ -7,7 +7,7 @@
 
 from rascal2.config import LOGGER, SETTINGS, MatlabHelper
 from rascal2.paths import MATLAB_ARCH_FILE
-from rascal2.settings import SettingsGroups
+from rascal2.settings import SettingsGroups, change_ui_style
 from rascal2.widgets.inputs import get_validated_input
 
 
@@ -69,6 +69,7 @@ def update_settings(self) -> None:
     def reset_default_settings(self) -> None:
         """Reset the settings to the global defaults."""
         SETTINGS.reset_global_settings()
+        change_ui_style()
         self.accept()
 
 
@@ -122,6 +123,10 @@ def modify_setting(self, setting: str):
         """
         setattr(self.settings, setting, self.widgets[setting].get_data())
 
+        match setting:
+            case "style":
+                change_ui_style(self.widgets[setting].get_data())
+
 
 class MatlabSetupTab(QtWidgets.QWidget):
     """Dialog to adjust Matlab location settings."""
diff --git a/rascal2/settings.py b/rascal2/settings.py
index 37619b2b..5456a581 100644
--- a/rascal2/settings.py
+++ b/rascal2/settings.py
@@ -13,7 +13,7 @@
 from typing import Any, TypeAlias
 
 from pydantic import BaseModel, Field
-from PyQt6 import QtCore
+from PyQt6 import QtCore, QtWidgets
 
 
 # we do this statically rather than making it an attribute of Settings because all fields in a Pydantic model
@@ -52,7 +52,9 @@ class SettingsGroups(StrEnum):
 class Styles(StrEnum):
     """Visual styles for RasCAL-2."""
 
+    System = "system"
     Light = "light"
+    Dark = "dark"
 
 
 class BackgroundColour(StrEnum):
@@ -117,7 +119,7 @@ class Settings(BaseModel, validate_assignment=True, arbitrary_types_allowed=True
 
     # The Settings object's own model fields contain the within-project settings.
     # The global settings are read and written via this object using `set_global_settings`.
-    style: Styles = Field(default=Styles.Light, title=SettingsGroups.General, description="Style")
+    style: Styles = Field(default=Styles.System, title=SettingsGroups.General, description="Style")
     editor_fontsize: int = Field(default=12, title=SettingsGroups.General, description="Editor Font Size", gt=0)
     matlab_as_default_editor: bool = Field(
         default=False,
@@ -159,7 +161,7 @@ def save(self, path: str | PathLike):
     def set_global_settings(self):
         """Set manually-set local settings as global settings."""
         global_settings = get_global_settings()
-        for setting in self.model_fields_set:
+        for setting in self.model_fields:
             global_settings.setValue(global_name(setting), getattr(self, setting))
         global_settings.sync()
 
@@ -225,3 +227,29 @@ def update_recent_projects(path: str | None = None) -> list[str]:
     settings.setValue("recent_projects", new_recent_projects)
     settings.sync()
     return new_recent_projects
+
+
+def get_colour_scheme():
+    """Get the currently selected colour scheme and converts it to relevant Qt colour scheme flag."""
+    colour_scheme = get_global_settings().value("General/style", "system")
+    match colour_scheme:
+        case "system":
+            colour_scheme_default = QtCore.Qt.ColorScheme.Unknown
+        case "light":
+            colour_scheme_default = QtCore.Qt.ColorScheme.Light
+        case "dark":
+            colour_scheme_default = QtCore.Qt.ColorScheme.Dark
+    return colour_scheme_default
+
+
+def change_ui_style(style: Styles = Styles.System) -> None:
+    """Change the style of the app GUI to the given style."""
+    app = QtWidgets.QApplication.instance()
+    match style:
+        case "system":
+            colour_scheme = QtCore.Qt.ColorScheme.Unknown
+        case "light":
+            colour_scheme = QtCore.Qt.ColorScheme.Light
+        case "dark":
+            colour_scheme = QtCore.Qt.ColorScheme.Dark
+    app.styleHints().setColorScheme(colour_scheme)
diff --git a/rascal2/static/images/banner-dark.png b/rascal2/static/images/banner-dark.png
new file mode 100644
index 00000000..08e4379b
Binary files /dev/null and b/rascal2/static/images/banner-dark.png differ
diff --git a/rascal2/static/images/banner.png b/rascal2/static/images/banner-light.png
similarity index 100%
rename from rascal2/static/images/banner.png
rename to rascal2/static/images/banner-light.png
diff --git a/rascal2/static/images/browse-dark.png b/rascal2/static/images/browse-dark.png
index a89ceba0..4cf6e694 100644
Binary files a/rascal2/static/images/browse-dark.png and b/rascal2/static/images/browse-dark.png differ
diff --git a/rascal2/static/images/browse-light.png b/rascal2/static/images/browse-light.png
index 4cf6e694..a89ceba0 100644
Binary files a/rascal2/static/images/browse-light.png and b/rascal2/static/images/browse-light.png differ
diff --git a/rascal2/static/images/cancel-dark.png b/rascal2/static/images/cancel-dark.png
index 71041a03..71a9b88c 100644
Binary files a/rascal2/static/images/cancel-dark.png and b/rascal2/static/images/cancel-dark.png differ
diff --git a/rascal2/static/images/cancel-light.png b/rascal2/static/images/cancel-light.png
index 71a9b88c..71041a03 100644
Binary files a/rascal2/static/images/cancel-light.png and b/rascal2/static/images/cancel-light.png differ
diff --git a/rascal2/static/images/create-dark.png b/rascal2/static/images/create-dark.png
index 99544ce8..4dd1a10a 100644
Binary files a/rascal2/static/images/create-dark.png and b/rascal2/static/images/create-dark.png differ
diff --git a/rascal2/static/images/create-light.png b/rascal2/static/images/create-light.png
index 4dd1a10a..99544ce8 100644
Binary files a/rascal2/static/images/create-light.png and b/rascal2/static/images/create-light.png differ
diff --git a/rascal2/static/images/delete-dark.png b/rascal2/static/images/delete-dark.png
index eaef9b00..17c58783 100644
Binary files a/rascal2/static/images/delete-dark.png and b/rascal2/static/images/delete-dark.png differ
diff --git a/rascal2/static/images/delete-light.png b/rascal2/static/images/delete-light.png
new file mode 100644
index 00000000..eaef9b00
Binary files /dev/null and b/rascal2/static/images/delete-light.png differ
diff --git a/rascal2/static/images/edit-dark.png b/rascal2/static/images/edit-dark.png
new file mode 100644
index 00000000..6be929cf
Binary files /dev/null and b/rascal2/static/images/edit-dark.png differ
diff --git a/rascal2/static/images/edit.png b/rascal2/static/images/edit-light.png
similarity index 100%
rename from rascal2/static/images/edit.png
rename to rascal2/static/images/edit-light.png
diff --git a/rascal2/static/images/load-dark.png b/rascal2/static/images/footer-dark.png
similarity index 56%
rename from rascal2/static/images/load-dark.png
rename to rascal2/static/images/footer-dark.png
index c95a405a..f1debb61 100644
Binary files a/rascal2/static/images/load-dark.png and b/rascal2/static/images/footer-dark.png differ
diff --git a/rascal2/static/images/footer.png b/rascal2/static/images/footer-light.png
similarity index 100%
rename from rascal2/static/images/footer.png
rename to rascal2/static/images/footer-light.png
diff --git a/rascal2/static/images/help-dark.png b/rascal2/static/images/help-dark.png
new file mode 100644
index 00000000..d512a035
Binary files /dev/null and b/rascal2/static/images/help-dark.png differ
diff --git a/rascal2/static/images/help.png b/rascal2/static/images/help-light.png
similarity index 100%
rename from rascal2/static/images/help.png
rename to rascal2/static/images/help-light.png
diff --git a/rascal2/static/images/hide-settings-dark.png b/rascal2/static/images/hide-settings-dark.png
new file mode 100644
index 00000000..eeeba442
Binary files /dev/null and b/rascal2/static/images/hide-settings-dark.png differ
diff --git a/rascal2/static/images/hide-settings.png b/rascal2/static/images/hide-settings-light.png
similarity index 100%
rename from rascal2/static/images/hide-settings.png
rename to rascal2/static/images/hide-settings-light.png
diff --git a/rascal2/static/images/import-r1-light.png b/rascal2/static/images/import-r1.png
similarity index 100%
rename from rascal2/static/images/import-r1-light.png
rename to rascal2/static/images/import-r1.png
diff --git a/rascal2/static/images/new-project-dark.png b/rascal2/static/images/new-project-dark.png
new file mode 100644
index 00000000..2d98164f
Binary files /dev/null and b/rascal2/static/images/new-project-dark.png differ
diff --git a/rascal2/static/images/new-project.png b/rascal2/static/images/new-project-light.png
similarity index 100%
rename from rascal2/static/images/new-project.png
rename to rascal2/static/images/new-project-light.png
diff --git a/rascal2/static/images/play-dark.png b/rascal2/static/images/play-dark.png
deleted file mode 100644
index 832a3759..00000000
Binary files a/rascal2/static/images/play-dark.png and /dev/null differ
diff --git a/rascal2/static/images/redo-dark.png b/rascal2/static/images/redo-dark.png
new file mode 100644
index 00000000..85812186
Binary files /dev/null and b/rascal2/static/images/redo-dark.png differ
diff --git a/rascal2/static/images/redo.png b/rascal2/static/images/redo-light.png
similarity index 100%
rename from rascal2/static/images/redo.png
rename to rascal2/static/images/redo-light.png
diff --git a/rascal2/static/images/refresh-dark.png b/rascal2/static/images/refresh-dark.png
new file mode 100644
index 00000000..24c5d1ae
Binary files /dev/null and b/rascal2/static/images/refresh-dark.png differ
diff --git a/rascal2/static/images/refresh.png b/rascal2/static/images/refresh-light.png
similarity index 100%
rename from rascal2/static/images/refresh.png
rename to rascal2/static/images/refresh-light.png
diff --git a/rascal2/static/images/save-project-dark.png b/rascal2/static/images/save-project-dark.png
new file mode 100644
index 00000000..8ec24818
Binary files /dev/null and b/rascal2/static/images/save-project-dark.png differ
diff --git a/rascal2/static/images/save-project.png b/rascal2/static/images/save-project-light.png
similarity index 100%
rename from rascal2/static/images/save-project.png
rename to rascal2/static/images/save-project-light.png
diff --git a/rascal2/static/images/settings-dark.png b/rascal2/static/images/settings-dark.png
new file mode 100644
index 00000000..9c19273d
Binary files /dev/null and b/rascal2/static/images/settings-dark.png differ
diff --git a/rascal2/static/images/settings.png b/rascal2/static/images/settings-light.png
similarity index 100%
rename from rascal2/static/images/settings.png
rename to rascal2/static/images/settings-light.png
diff --git a/rascal2/static/images/stop-dark.png b/rascal2/static/images/stop-dark.png
deleted file mode 100644
index a5922e6c..00000000
Binary files a/rascal2/static/images/stop-dark.png and /dev/null differ
diff --git a/rascal2/static/images/tile-dark.png b/rascal2/static/images/tile-dark.png
new file mode 100644
index 00000000..1067306e
Binary files /dev/null and b/rascal2/static/images/tile-dark.png differ
diff --git a/rascal2/static/images/tile.png b/rascal2/static/images/tile-light.png
similarity index 100%
rename from rascal2/static/images/tile.png
rename to rascal2/static/images/tile-light.png
diff --git a/rascal2/static/images/undo-dark.png b/rascal2/static/images/undo-dark.png
new file mode 100644
index 00000000..50172f76
Binary files /dev/null and b/rascal2/static/images/undo-dark.png differ
diff --git a/rascal2/static/images/undo.png b/rascal2/static/images/undo-light.png
similarity index 100%
rename from rascal2/static/images/undo.png
rename to rascal2/static/images/undo-light.png
diff --git a/rascal2/static/style.css b/rascal2/static/style.css
index ed6d7259..37f492b9 100644
--- a/rascal2/static/style.css
+++ b/rascal2/static/style.css
@@ -5,7 +5,7 @@
 }
 
 QDialog{
-    border: 1px solid #ddd;
+    border: 1px solid darkgray;
 }
 
 QToolBar {
@@ -23,11 +23,11 @@ QSpinBox, QDoubleSpinBox, QAbstractSpinBox, QLineEdit, QComboBox {
 
 QStatusBar {
     min-height: 20px;
-    border-top: 1px solid #ddd;
+    border-top: 1px solid @Midlight;
 }
 
 QPushButton {
-    background-color: white;
+    background-color: @Button;
     text-align: center;
     border: 1px solid #828282;
     padding: 5px 12px 5px 12px;
@@ -37,14 +37,16 @@ QPushButton {
     min-height: 14px;
 }
 
+QPushButton:focus,
 QPushButton:hover,
-QPushButton:focus {
-    color: black;
-    border-color: #3874f2;
+QPushButton:pressed {
+    color: @Text;
+    border-color: @Highlight;
 }
 
-QPushButton:hover{
-    background-color: #e0eef9;
+QPushButton:hover,
+QPushButton:pressed {
+    background-color: @Highlight;
 }
 
 QPushButton:disabled,
@@ -54,26 +56,22 @@ QPushButton:disabled:checked {
     border-color: #b6b6b6;
 }
 
-QPushButton:pressed {
-    background-color: #3874f2;
-}
-
 QPushButton:checked {
     background-color: #5e90fa;
     border-color: #3874f2;
 }
 
 QLineEdit {
-    color: black;
-    background-color: white;
-    selection-color: black;
+    color: @Text;
+    background-color: @Base;
+    selection-color: @Text;
     selection-background-color: @Highlight;
-    border: 1px solid #aaa;
+    border: 1px solid darkgray;
     border-radius: 3px;
 }
 
 QLineEdit:read-only {
-    selection-color: black;
+    selection-color: @Text;
     selection-background-color: @Highlight;
     background-color: transparent;
 }
@@ -133,15 +131,15 @@ StartUpWidget QLabel {
 }
 
 StartUpWidget QToolButton#NewProjectButton{
-    image: url(@Path/create-light.png);
+    image: url(@Path/create-dark.png);
 }
 
 StartUpWidget QToolButton#ImportProjectButton{
-    image: url(@Path/browse-light.png);
+    image: url(@Path/browse-dark.png);
 }
 
 StartUpWidget QToolButton#ImportR1Button{
-    image: url(@Path/import-r1-light.png);
+    image: url(@Path/import-r1.png);
 }
 
 /*****************************
@@ -153,15 +151,15 @@ StartupDialog #CancelButton {
 }
 
 StartupDialog #BrowseButton {
-    icon: url(@Path/browse-dark.png);
+    icon: url(@Path/browse-light.png);
 }
 
 StartupDialog #CreateButton {
-    icon: url(@Path/create-dark.png);
+    icon: url(@Path/create-light.png);
 }
 
 StartupDialog #LoadButton {
-    icon: url(@Path/load-dark.png);
+    icon: url(@Path/load-light.png);
 }
 
 StartupDialog > QLabel {
@@ -204,7 +202,7 @@ DisplayWidget #title{
 }
 
 DisplayWidget #desc{
-    color: #555
+    color: @text
 }
 
 /*****************************
@@ -228,17 +226,17 @@ ProjectWidget QPushButton{
 }
 
 #InteractButton {
-    background-color: #dadbde;
+    background-color: @Button;
 }
 
 #InteractButton:hover,
 #InteractButton:focus {
-    color: black;
-    border-color: #3874f2;
+    color: @Text;
+    border-color: darkgray;
 }
 
 #InteractButton:hover{
-    background-color: #e0eef9;
+    background-color: @Button;
 }
 
 #InteractButton:pressed {
@@ -247,7 +245,7 @@ ProjectWidget QPushButton{
 
 #InteractButton:checked {
     background-color: @Highlight;
-    border-color: #3874f2;
+    border-color: darkgray;
 }
 
 /*****************************
@@ -255,12 +253,12 @@ ProjectWidget QPushButton{
 *****************************/
 
 TerminalWidget QPlainTextEdit{
-    background-color: white;
+    background-color: @Base;
 }
 
 TerminalWidget QProgressBar{
     border-radius: 0px;
-    border: 1px solid grey;
+    border: 1px solid @Midlight;
     text-align: center;
 }
 
@@ -269,7 +267,7 @@ TerminalWidget QProgressBar{
 *****************************/
 
 ControlsWidget #FitSettings{
-    background-color: white;
+    background-color: @Base;
 }
 
 ControlsWidget QPushButton {
@@ -331,14 +329,14 @@ QTabWidget:focus {
 }
 
 QTabWidget::pane {
-  border: 1px solid lightgray;
+  border: 1px solid darkgray;
   top:-1px;
-  background: #f5f5f5;;
+  background: @Window;;
 }
 
 QTabBar::tab {
-  background: #e6e6e6;
-  border: 1px solid lightgray;
+  background: @Base;
+  border: 1px solid darkgray;
   padding: 10px;
 }
 
@@ -357,12 +355,12 @@ QTabBar::tab:selected {
 
 QTableView
 {
-  background-color: white;
+  background-color: @Base;
 }
 
 QTableView::disabled
 {
-  background-color: @Window;
+  background-color: @Midlight;
 }
 
 QTableView item
@@ -389,7 +387,7 @@ QTableView QPushButton {
 *****************************/
 
 QMenuBar {
-  background-color: white;
+  background-color: @Window;
 }
 
 QMenuBar:disabled,
@@ -425,7 +423,7 @@ AbstractProjectListWidget QPushButton {
 
 AbstractProjectListWidget QTableView {
     border: 1px solid @Midlight;
-    background-color: white;
+    background-color: @Window;
 }
 
 #CountHeader::section {
diff --git a/rascal2/theme.py b/rascal2/theme.py
new file mode 100644
index 00000000..8d803497
--- /dev/null
+++ b/rascal2/theme.py
@@ -0,0 +1,91 @@
+import re
+from contextlib import suppress
+
+from PyQt6 import QtCore, QtGui, QtWidgets
+
+from rascal2.paths import IMAGES_PATH, STATIC_PATH, path_for
+
+
+def set_stylesheet(app):
+    """Set the stylesheet of the app according to the given style.css file if available."""
+    with suppress(FileNotFoundError), open(STATIC_PATH / "style.css") as stylesheet:
+        palette = app.palette()
+        replacements = {
+            "@Path": IMAGES_PATH.as_posix(),
+            "@Window": palette.window().color().name(),
+            "@Highlight": palette.highlight().color().name(),
+            "@Midlight": palette.midlight().color().name(),
+            "@Text": palette.text().color().name(),
+        }
+        style = re.sub("|".join(replacements), lambda x: replacements[x.group(0)], stylesheet.read())
+        app.setStyleSheet(style)
+
+
+class ThemeManager(QtCore.QObject):
+    """Class to manage the Theme of the UI."""
+
+    def __init__(self):
+        super().__init__()
+        scheme = QtWidgets.QApplication.styleHints().colorScheme()
+        self.cur_style = "light" if scheme == QtCore.Qt.ColorScheme.Light else "dark"
+
+    def eventFilter(self, obj, event):
+        """Catch close event for overlay widget."""
+        if isinstance(obj, QtWidgets.QApplication) and event.type() == QtCore.QEvent.Type.ApplicationPaletteChange:
+            scheme = QtWidgets.QApplication.styleHints().colorScheme()
+            style = "light" if scheme == QtCore.Qt.ColorScheme.Light else "dark"
+            if style != self.cur_style:
+                set_stylesheet(obj)
+                print(type(obj))
+                self.cur_style = style
+                return True
+        return False
+
+
+THEMES = ThemeManager()
+
+
+class IconEngine(QtGui.QIconEngine):
+    """Create the icons for the application."""
+
+    def __init__(self, filename):
+        super().__init__()
+        self.name = re.split(r"-dark.png|-light.png", filename)[0]
+        self.update_icon()
+
+    def update_icon(self):
+        """Update the Icon."""
+        scheme = QtWidgets.QApplication.styleHints().colorScheme()
+        style = "light" if scheme == QtCore.Qt.ColorScheme.Light else "dark"
+
+        filename = f"{self.name}-light.png" if style == "light" else f"{self.name}-dark.png"
+        path = path_for(filename)
+        self.icon = QtGui.QIcon(path)
+
+    def pixmap(self, size, mode, state):
+        """Create the pixmap.
+
+        :param size: size
+        :type size: QSize
+        :param mode: mode
+        :type mode: QIcon.Mode
+        :param state: state
+        :type state: QIcon.State
+        """
+        self.update_icon()
+        return self.icon.pixmap(size, mode, state)
+
+    def paint(self, painter, rect, mode, state):
+        """Paint the icon.
+
+        :param painter: painter
+        :type painter: QPainter
+        :param rect: rect
+        :type rect: QRect
+        :param mode: mode
+        :type mode: QIcon.Mode
+        :param state: state
+        :type state: QIcon.State
+        """
+        self.update_icon()
+        return self.icon.pixmap.paint(painter, rect, mode, state)
diff --git a/rascal2/ui/view.py b/rascal2/ui/view.py
index 54ec00a3..6325910b 100644
--- a/rascal2/ui/view.py
+++ b/rascal2/ui/view.py
@@ -9,6 +9,7 @@
 from rascal2.dialogs.startup_dialog import PROJECT_FILES, LoadDialog, LoadR1Dialog, NewProjectDialog, StartupDialog
 from rascal2.paths import EXAMPLES_PATH, EXAMPLES_TEMP_PATH, path_for
 from rascal2.settings import MDIGeometries, get_global_settings
+from rascal2.theme import IconEngine
 from rascal2.widgets import ControlsWidget, PlotWidget, TerminalWidget
 from rascal2.widgets.project import ProjectWidget
 from rascal2.widgets.startup import StartUpWidget
@@ -18,6 +19,24 @@
 MAIN_WINDOW_TITLE = "RasCAL-2"
 
 
+class TitleProxyStyle(QtWidgets.QProxyStyle):
+    """Set style of Title bar."""
+
+    def drawComplexControl(self, control, option, painter, widget=None):
+        if control == QtWidgets.QStyle.ComplexControl.CC_TitleBar:
+            option.palette.setBrush(QtGui.QPalette.ColorRole.Window, option.palette.button().color())
+        super().drawComplexControl(control, option, painter, widget)
+
+
+class MdiSubWindow(QtWidgets.QMdiSubWindow):
+    """Class to handle MDI sub-windows."""
+
+    def __init__(self, parent=None, flags=QtCore.Qt.WindowType.Widget):
+        super().__init__(parent, flags)
+        style = TitleProxyStyle(self.style())
+        self.setStyle(style)
+
+
 class MainWindowView(QtWidgets.QMainWindow):
     """Creates the main view for the RasCAL application."""
 
@@ -98,13 +117,13 @@ def create_actions(self):
         """Create the menu and toolbar actions."""
         self.new_project_action = QtGui.QAction("&New Project", self)
         self.new_project_action.setStatusTip("Create a new project")
-        self.new_project_action.setIcon(QtGui.QIcon(path_for("new-project.png")))
+        self.new_project_action.setIcon(QtGui.QIcon(IconEngine("new-project-light.png")))
         self.new_project_action.triggered.connect(lambda: self.show_project_dialog(NewProjectDialog))
         self.new_project_action.setShortcut(QtGui.QKeySequence.StandardKey.New)
 
         self.open_project_action = QtGui.QAction("&Open Project", self)
         self.open_project_action.setStatusTip("Open an existing project")
-        self.open_project_action.setIcon(QtGui.QIcon(path_for("browse-dark.png")))
+        self.open_project_action.setIcon(QtGui.QIcon(IconEngine("browse-light.png")))
         self.open_project_action.triggered.connect(lambda: self.show_project_dialog(LoadDialog))
         self.open_project_action.setShortcut(QtGui.QKeySequence.StandardKey.Open)
 
@@ -114,7 +133,7 @@ def create_actions(self):
 
         self.save_project_action = QtGui.QAction("&Save", self)
         self.save_project_action.setStatusTip("Save project")
-        self.save_project_action.setIcon(QtGui.QIcon(path_for("save-project.png")))
+        self.save_project_action.setIcon(QtGui.QIcon(IconEngine("save-project-light.png")))
         self.save_project_action.triggered.connect(lambda: self.presenter.save_project())
         self.save_project_action.setShortcut(QtGui.QKeySequence.StandardKey.Save)
         self.save_project_action.setEnabled(False)
@@ -122,7 +141,7 @@ def create_actions(self):
 
         self.save_as_action = QtGui.QAction("Save To &Folder...", self)
         self.save_as_action.setStatusTip("Save project to a specified folder.")
-        self.save_as_action.setIcon(QtGui.QIcon(path_for("save-project.png")))
+        self.save_as_action.setIcon(QtGui.QIcon(IconEngine("save-project-light.png")))
         self.save_as_action.triggered.connect(lambda: self.presenter.save_project(save_as=True))
         self.save_as_action.setShortcut(QtGui.QKeySequence.StandardKey.SaveAs)
         self.save_as_action.setEnabled(False)
@@ -137,12 +156,12 @@ def create_actions(self):
 
         self.undo_action = self.undo_stack.createUndoAction(self, "&Undo")
         self.undo_action.setStatusTip("Undo the last action")
-        self.undo_action.setIcon(QtGui.QIcon(path_for("undo.png")))
+        self.undo_action.setIcon(QtGui.QIcon(IconEngine("undo-light.png")))
         self.undo_action.setShortcut(QtGui.QKeySequence.StandardKey.Undo)
 
         self.redo_action = self.undo_stack.createRedoAction(self, "&Redo")
         self.redo_action.setStatusTip("Redo the last undone action")
-        self.redo_action.setIcon(QtGui.QIcon(path_for("redo.png")))
+        self.redo_action.setIcon(QtGui.QIcon(IconEngine("redo-light.png")))
         self.redo_action.setShortcut(QtGui.QKeySequence.StandardKey.Redo)
 
         self.undo_view_action = QtGui.QAction("Undo &History", self)
@@ -159,13 +178,13 @@ def create_actions(self):
 
         self.settings_action = QtGui.QAction("Settings", self)
         self.settings_action.setStatusTip("Settings")
-        self.settings_action.setIcon(QtGui.QIcon(path_for("settings.png")))
+        self.settings_action.setIcon(QtGui.QIcon(IconEngine("settings-light.png")))
         self.settings_action.setMenuRole(QtGui.QAction.MenuRole.PreferencesRole)
         self.settings_action.triggered.connect(lambda: self.show_settings_dialog())
 
         self.open_help_action = QtGui.QAction("&Help", self)
         self.open_help_action.setStatusTip("Open Documentation")
-        self.open_help_action.setIcon(QtGui.QIcon(path_for("help.png")))
+        self.open_help_action.setIcon(QtGui.QIcon(IconEngine("help-light.png")))
         self.open_help_action.triggered.connect(self.open_docs)
 
         self.toggle_slider_action = QtGui.QAction("Show &Sliders", self)
@@ -191,7 +210,7 @@ def create_actions(self):
         # Window menu actions
         self.tile_windows_action = QtGui.QAction("Tile Windows", self)
         self.tile_windows_action.setStatusTip("Arrange windows in the default grid.")
-        self.tile_windows_action.setIcon(QtGui.QIcon(path_for("tile.png")))
+        self.tile_windows_action.setIcon(QtGui.QIcon(IconEngine("tile-light.png")))
         self.tile_windows_action.triggered.connect(self.custom_tile_layout)
         self.tile_windows_action.setEnabled(False)
         self.disabled_elements.append(self.tile_windows_action)
@@ -284,6 +303,7 @@ def open_docs(self):
     def create_toolbar(self):
         """Create the toolbar."""
         self.toolbar = self.addToolBar("ToolBar")
+        self.toolbar.setStyleSheet("QToolButton { padding-left: 5px; padding-right: 5px; padding-top: 10px }")
         self.toolbar.setContextMenuPolicy(QtCore.Qt.ContextMenuPolicy.PreventContextMenu)
         self.toolbar.setMovable(False)
 
@@ -321,6 +341,8 @@ def setup_mdi(self):
             window = self.mdi.addSubWindow(
                 widget, QtCore.Qt.WindowType.WindowMinMaxButtonsHint | QtCore.Qt.WindowType.WindowTitleHint
             )
+            # window = MdiSubWindow(self.mdi)
+            # window.setWidget(widget)
             window.setWindowTitle(title)
         self.reset_mdi_layout()
         self.startup_dlg = self.takeCentralWidget()
diff --git a/rascal2/widgets/inputs.py b/rascal2/widgets/inputs.py
index 6a7eb969..9a5ee3df 100644
--- a/rascal2/widgets/inputs.py
+++ b/rascal2/widgets/inputs.py
@@ -674,13 +674,13 @@ def __init__(self, parent=None):
         self.setLayout(layout)
         self.select_menu = QtWidgets.QMenu()
 
-        add_button = QtWidgets.QToolButton(icon=QtGui.QIcon(path_for("create-dark.png")))
+        add_button = QtWidgets.QToolButton(icon=QtGui.QIcon(path_for("create-light.png")))
         add_button.setMinimumWidth(40)
         add_button.setSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.MinimumExpanding)
         add_button.setPopupMode(QtWidgets.QToolButton.ToolButtonPopupMode.InstantPopup)
         add_button.setMenu(self.select_menu)
 
-        delete_button = QtWidgets.QToolButton(icon=QtGui.QIcon(path_for("delete-dark.png")))
+        delete_button = QtWidgets.QToolButton(icon=QtGui.QIcon(path_for("delete-light.png")))
         delete_button.setMinimumWidth(40)
         delete_button.clicked.connect(self.delete_items)
         delete_button.setSizePolicy(
diff --git a/rascal2/widgets/plot.py b/rascal2/widgets/plot.py
index 21948913..65ba9de2 100644
--- a/rascal2/widgets/plot.py
+++ b/rascal2/widgets/plot.py
@@ -9,7 +9,7 @@
 from PyQt6 import QtCore, QtGui, QtWidgets
 
 from rascal2.config import SETTINGS
-from rascal2.paths import path_for
+from rascal2.theme import IconEngine
 from rascal2.widgets.inputs import MultiSelectComboBox, ProgressButton
 
 
@@ -311,7 +311,7 @@ def make_interaction_layout(self):
         self.toolbar.hide()
         reset_button = QtWidgets.QToolButton(objectName="InteractButton")
         reset_button.setToolTip("Reset plot")
-        reset_button.setIcon(QtGui.QIcon(path_for("refresh.png")))
+        reset_button.setIcon(QtGui.QIcon(IconEngine("refresh-dark.png")))
         reset_button.clicked.connect(lambda: self.toolbar.home())
         pan_button = QtWidgets.QToolButton(objectName="InteractButton")
         pan_button.setDefaultAction(self.toolbar._actions["pan"])
@@ -330,9 +330,9 @@ def toggle_settings(self, toggled_on: bool):
         """Toggles the visibility of the plot controls."""
         self.plot_controls.setVisible(toggled_on)
         if toggled_on:
-            self.toggle_button.setIcon(QtGui.QIcon(path_for("hide-settings.png")))
+            self.toggle_button.setIcon(QtGui.QIcon(IconEngine("hide-settings-light.png")))
         else:
-            self.toggle_button.setIcon(QtGui.QIcon(path_for("settings.png")))
+            self.toggle_button.setIcon(QtGui.QIcon(IconEngine("settings-light.png")))
 
     @abstractmethod
     def make_control_layout(self) -> QtWidgets.QLayout:
@@ -390,6 +390,16 @@ def export(self):
             dpi = self.figure.dpi if sx > 1920 else 1920 // self.figure.get_figwidth()
             self.figure.savefig(filepath, facecolor=SETTINGS.export_background_colour, dpi=dpi)
 
+    def changeEvent(self, event):
+        if event.type() == QtCore.QEvent.Type.PaletteChange:
+            scheme = QtWidgets.QApplication.styleHints().colorScheme()
+            if scheme == QtCore.Qt.ColorScheme.Light:
+                matplotlib.style.use("default")
+            else:
+                matplotlib.style.use("dark_background")
+
+        super().changeEvent(event)
+
 
 class RefSLDWidget(AbstractPlotWidget):
     """Creates a UI for displaying the path lengths from the simulation result."""
diff --git a/rascal2/widgets/project/lists.py b/rascal2/widgets/project/lists.py
index a39b3914..f6181e61 100644
--- a/rascal2/widgets/project/lists.py
+++ b/rascal2/widgets/project/lists.py
@@ -11,7 +11,7 @@
 
 from rascal2.config import SETTINGS
 from rascal2.core.readers import readers
-from rascal2.paths import path_for
+from rascal2.theme import IconEngine
 from rascal2.widgets.delegates import ProjectFieldDelegate
 from rascal2.widgets.inputs import RangeWidget
 
@@ -135,12 +135,12 @@ def __init__(self, field: str, parent):
         button_layout = QtWidgets.QHBoxLayout()
         button_layout.setContentsMargins(0, 0, 0, 0)
         button_layout.addStretch(1)
-        self.add_button = QtWidgets.QToolButton(icon=QtGui.QIcon(path_for("create-dark.png")))
+        self.add_button = QtWidgets.QToolButton(icon=QtGui.QIcon(IconEngine("create-light.png")))
         self.add_button.setHidden(True)
         self.add_button.pressed.connect(self.append_item)
         button_layout.addWidget(self.add_button)
 
-        self.delete_button = QtWidgets.QToolButton(icon=QtGui.QIcon(path_for("delete-dark.png")))
+        self.delete_button = QtWidgets.QToolButton(icon=QtGui.QIcon(IconEngine("delete-light.png")))
         self.delete_button.setHidden(True)
         self.delete_button.pressed.connect(self.delete_item)
         button_layout.addWidget(self.delete_button)
@@ -379,14 +379,14 @@ def setup_buttons(self):
         model_type = "domain contrast" if self.domains else "layer"
 
         self.add_button = QtWidgets.QPushButton(
-            f"Add {model_type.title()}", icon=QtGui.QIcon(path_for("create-dark.png"))
+            f"Add {model_type.title()}", icon=QtGui.QIcon(IconEngine("create-light.png"))
         )
         self.add_button.setToolTip(
             f"Add a {model_type.title()} after the currently selected {model_type.title()} (Shift+Enter)"
         )
 
         self.delete_button = QtWidgets.QPushButton(
-            f"Delete {model_type.title()}", icon=QtGui.QIcon(path_for("delete-dark.png"))
+            f"Delete {model_type.title()}", icon=QtGui.QIcon(IconEngine("delete-light.png"))
         )
         self.delete_button.setToolTip(f"Delete the currently selected {model_type.title()} (Del)")
 
diff --git a/rascal2/widgets/project/project.py b/rascal2/widgets/project/project.py
index bdd2743a..5600b260 100644
--- a/rascal2/widgets/project/project.py
+++ b/rascal2/widgets/project/project.py
@@ -11,7 +11,7 @@
 from ratapi.utils.custom_errors import custom_pydantic_validation_error
 from ratapi.utils.enums import Calculations, Geometries, LayerModels
 
-from rascal2.paths import path_for
+from rascal2.theme import IconEngine
 from rascal2.widgets.project.lists import ContrastWidget, DataWidget
 from rascal2.widgets.project.slider_view import SliderViewWidget
 from rascal2.widgets.project.tables import (
@@ -119,7 +119,7 @@ def create_project_view(self) -> QtWidgets.QWidget:
         show_sliders_button = QtWidgets.QPushButton("Show sliders")
         show_sliders_button.clicked.connect(self.parent.toggle_sliders)
 
-        self.edit_project_button = QtWidgets.QPushButton("Edit Project", icon=QtGui.QIcon(path_for("edit.png")))
+        self.edit_project_button = QtWidgets.QPushButton("Edit Project", icon=QtGui.QIcon(IconEngine("edit-light.png")))
         self.edit_project_button.clicked.connect(self.show_edit_view)
         button_layout = QtWidgets.QHBoxLayout()
         button_layout.setAlignment(QtCore.Qt.AlignmentFlag.AlignRight)
@@ -169,11 +169,11 @@ def create_edit_view(self) -> QtWidgets.QWidget:
         main_layout.setSpacing(20)
 
         self.save_project_button = QtWidgets.QPushButton(
-            "Accept Changes", icon=QtGui.QIcon(path_for("save-project.png"))
+            "Accept Changes", icon=QtGui.QIcon(IconEngine("save-project-light.png"))
         )
         self.save_project_button.clicked.connect(self.save_changes)
 
-        self.cancel_button = QtWidgets.QPushButton("Cancel", icon=QtGui.QIcon(path_for("cancel-dark.png")))
+        self.cancel_button = QtWidgets.QPushButton("Cancel", icon=QtGui.QIcon(IconEngine("cancel-light.png")))
         self.cancel_button.clicked.connect(self.show_project_view)
 
         buttons_layout = QtWidgets.QHBoxLayout()
diff --git a/rascal2/widgets/project/tables.py b/rascal2/widgets/project/tables.py
index 45eb7fd2..b765af7c 100644
--- a/rascal2/widgets/project/tables.py
+++ b/rascal2/widgets/project/tables.py
@@ -16,7 +16,7 @@
 from rascal2.config import LOGGER, SETTINGS
 from rascal2.core.enums import CustomFileType
 from rascal2.dialogs.custom_file_editor import create_new_file, edit_file
-from rascal2.paths import path_for
+from rascal2.theme import IconEngine
 
 
 class ClassListTableModel(QtCore.QAbstractTableModel):
@@ -363,7 +363,7 @@ def make_delete_button(self, index):
             The row to be deleted.
 
         """
-        button = QtWidgets.QPushButton(icon=QtGui.QIcon(path_for("delete-dark.png")))
+        button = QtWidgets.QPushButton(icon=QtGui.QIcon(IconEngine("delete-light.png")))
         button.resize(button.sizeHint().width(), button.sizeHint().width())
         button.pressed.connect(lambda: self.delete_item(index))
 
diff --git a/rascal2/widgets/startup.py b/rascal2/widgets/startup.py
index 5185edd6..2845d4ef 100644
--- a/rascal2/widgets/startup.py
+++ b/rascal2/widgets/startup.py
@@ -50,11 +50,11 @@ def add_widgets_to_layout(self) -> None:
     def create_banner_and_footer(self) -> None:
         """Create banner and footer."""
         self.banner_label = QtWidgets.QLabel()
-        self.banner_label.setPixmap(QtGui.QPixmap(path_for("banner.png")))
+        self.banner_label.setPixmap(QtGui.QPixmap(path_for("banner-light.png")))
         self.banner_label.setAlignment(QtCore.Qt.AlignmentFlag.AlignCenter)
 
         self.footer_label = QtWidgets.QLabel()
-        self.footer_label.setPixmap(QtGui.QPixmap(path_for("footer.png")))
+        self.footer_label.setPixmap(QtGui.QPixmap(path_for("footer-light.png")))
         self.footer_label.setAlignment(QtCore.Qt.AlignmentFlag.AlignCenter)
 
     def create_buttons(self) -> None:
@@ -78,3 +78,15 @@ def create_labels(self) -> None:
 
         self.import_r1_label = QtWidgets.QLabel("Import RasCAL-1\nProject")
         self.import_r1_label.setAlignment(QtCore.Qt.AlignmentFlag.AlignCenter)
+
+    def changeEvent(self, event):
+        if event.type() == QtCore.QEvent.Type.PaletteChange:
+            scheme = QtWidgets.QApplication.styleHints().colorScheme()
+            if scheme == QtCore.Qt.ColorScheme.Dark:
+                self.banner_label.setPixmap(QtGui.QPixmap(path_for("banner-dark.png")))
+                self.footer_label.setPixmap(QtGui.QPixmap(path_for("footer-dark.png")))
+            else:
+                self.banner_label.setPixmap(QtGui.QPixmap(path_for("banner-light.png")))
+                self.footer_label.setPixmap(QtGui.QPixmap(path_for("footer-light.png")))
+
+        super().changeEvent(event)
diff --git a/requirements.txt b/requirements.txt
index 652a092c..b3017b86 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 PyInstaller==6.9.0
-PyQt6==6.7.1
-PyQt6-Qt6==6.7.3
+PyQt6==6.8.1
+PyQt6-Qt6==6.8.2
 ratapi==0.0.0.dev14
 pydantic==2.8.2
 PyQt6-QScintilla==2.14.1