diff --git a/setup.cfg b/setup.cfg
index 144ec8b4f..701190af0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -46,6 +46,7 @@ install_requires =
     jill >=0.9.2
     pyzmq >=21.0
     spine-items >= 0.17.0
+    pyqtdarktheme >= 2.0
 include_package_data = True
 python_requires = >=3.8.1, <3.12
 
diff --git a/spinetoolbox/config.py b/spinetoolbox/config.py
index 8d86c1c5b..03dcebfe0 100644
--- a/spinetoolbox/config.py
+++ b/spinetoolbox/config.py
@@ -59,48 +59,51 @@
 PROJECT_ZIP_FILENAME = "project_package"  # ZIP-file name for remote execution
 
 # Stylesheets
-STATUSBAR_SS = "QStatusBar{background-color: #EBEBE0; border-width: 1px; border-color: gray; border-style: groove;}"
+STATUSBAR_SS = ""
+# STATUSBAR_SS = "QStatusBar{background-color: #EBEBE0; border-width: 1px; border-color: gray; border-style: groove;}"
 
 BG_COLOR = "#19232D"
 FG_COLOR = "#F0F0F0"
 
-SETTINGS_SS = (
-    "#SettingsForm{background-color: ghostwhite;}"
-    "QLabel{color: black;}"
-    "QGroupBox{border: 2px solid gray; "
-    "background-color: qlineargradient(x1: 0, y1: 0, x2: 1, y2: 0, stop: 0 #80B0FF, stop: 1 #e6efff);"
-    "border-radius: 5px;"
-    "margin-top: 0.5em;}"
-    "QGroupBox:title{border-radius: 2px; "
-    "background-color: ghostwhite;"
-    "subcontrol-origin: margin;"
-    "subcontrol-position: top center;"
-    "padding-top: 0px;"
-    "padding-bottom: 0px;"
-    "padding-right: 3px;"
-    "padding-left: 3px;}"
-    "QCheckBox{outline-style: dashed; outline-width: 1px; outline-color: white;}"
-    f"QPushButton{{background-color: #505F69; border: 1px solid #29353d; color: {FG_COLOR}; border-radius: 4px; padding: 3px; outline: none; min-width:80px}}"
-    "QPushButton:disabled {background-color: #32414B; border: 1px solid #29353d; color: #787878; border-radius: 4px; padding: 3px;}"
-    "QPushButton::menu-indicator {subcontrol-origin: padding; subcontrol-position: bottom right; bottom: 4px;}"
-    "QPushButton:focus{background-color: #637683; border: 1px solid #148CD2;}"
-    f"QPushButton:hover{{border: 1px solid #148CD2; color: {FG_COLOR};}}"
-    f"QPushButton:pressed{{background-color: {BG_COLOR}; border: 1px solid {BG_COLOR};}}"
-    "QSlider::groove:horizontal{background: #e1e1e1; border: 1px solid #a4a4a4; height: 5px; margin: 2px 0; border-radius: 2px;}"
-    "QSlider::handle:horizontal{background: #fafafa; border: 1px solid #a4a4a4; width: 12px; margin: -5px 0; border-radius: 2px;}"
-    "QSlider::add-page:horizontal{background: transparent;}"
-    "QSlider::sub-page:horizontal{background: transparent;}"
-)
+SETTINGS_SS = ""
+# SETTINGS_SS = (
+#     "#SettingsForm{background-color: ghostwhite;}"
+#     "QLabel{color: black;}"
+#     "QGroupBox{border: 2px solid gray; "
+#     "background-color: qlineargradient(x1: 0, y1: 0, x2: 1, y2: 0, stop: 0 #80B0FF, stop: 1 #e6efff);"
+#     "border-radius: 5px;"
+#     "margin-top: 0.5em;}"
+#     "QGroupBox:title{border-radius: 2px; "
+#     "background-color: ghostwhite;"
+#     "subcontrol-origin: margin;"
+#     "subcontrol-position: top center;"
+#     "padding-top: 0px;"
+#     "padding-bottom: 0px;"
+#     "padding-right: 3px;"
+#     "padding-left: 3px;}"
+#     "QCheckBox{outline-style: dashed; outline-width: 1px; outline-color: white;}"
+#     f"QPushButton{{background-color: #505F69; border: 1px solid #29353d; color: {FG_COLOR}; border-radius: 4px; padding: 3px; outline: none; min-width:80px}}"
+#     "QPushButton:disabled {background-color: #32414B; border: 1px solid #29353d; color: #787878; border-radius: 4px; padding: 3px;}"
+#     "QPushButton::menu-indicator {subcontrol-origin: padding; subcontrol-position: bottom right; bottom: 4px;}"
+#     "QPushButton:focus{background-color: #637683; border: 1px solid #148CD2;}"
+#     f"QPushButton:hover{{border: 1px solid #148CD2; color: {FG_COLOR};}}"
+#     f"QPushButton:pressed{{background-color: {BG_COLOR}; border: 1px solid {BG_COLOR};}}"
+#     "QSlider::groove:horizontal{background: #e1e1e1; border: 1px solid #a4a4a4; height: 5px; margin: 2px 0; border-radius: 2px;}"
+#     "QSlider::handle:horizontal{background: #fafafa; border: 1px solid #a4a4a4; width: 12px; margin: -5px 0; border-radius: 2px;}"
+#     "QSlider::add-page:horizontal{background: transparent;}"
+#     "QSlider::sub-page:horizontal{background: transparent;}"
+# )
 
 # ICON_BACKGROUND = "qlineargradient(x1: 1, y1: 1, x2: 0, y2: 0, stop: 0 #cce0ff, stop: 1 #66a1ff);"
 # ICON_TOOLBAR_SS = f"QToolBar{{spacing: 6px; background: {ICON_BACKGROUND}; padding: 3px; border-style: solid;}}"
 
-TEXTBROWSER_SS = (
-    f"QTextBrowser {{background-color: {BG_COLOR}; border: 1px solid #32414B; color: {FG_COLOR}; border-radius: 2px;}}"
-    "QTextBrowser:hover,"
-    "QTextBrowser:selected,"
-    "QTextBrowser:pressed {border: 1px solid #668599;}"
-)
+TEXTBROWSER_SS = ""
+# TEXTBROWSER_SS = (
+#     f"QTextBrowser {{background-color: {BG_COLOR}; border: 1px solid #32414B; color: {FG_COLOR}; border-radius: 2px;}}"
+#     "QTextBrowser:hover,"
+#     "QTextBrowser:selected,"
+#     "QTextBrowser:pressed {border: 1px solid #668599;}"
+# )
 
 # ToolboxUI stylesheet. A lot of widgets inherit this sheet.
 MAINWINDOW_SS = (
diff --git a/spinetoolbox/helpers.py b/spinetoolbox/helpers.py
index 5367c60f4..e23c319eb 100644
--- a/spinetoolbox/helpers.py
+++ b/spinetoolbox/helpers.py
@@ -101,7 +101,7 @@ def format_log_message(msg_type, message, show_datetime=True):
     Returns:
         str: formatted message
     """
-    color = {"msg": "white", "msg_success": "#00ff00", "msg_error": "#ff3333", "msg_warning": "yellow"}[msg_type]
+    color = {"msg": "", "msg_success": "#00ff00", "msg_error": "#ff3333", "msg_warning": "yellow"}[msg_type]
     open_tag = f"<span style='color:{color};white-space: pre-wrap;'>"
     date_str = get_datetime(show=show_datetime)
     return open_tag + date_str + message + "</span>"
@@ -1008,7 +1008,8 @@ def make_icon_background(color):
 def make_icon_toolbar_ss(color):
     icon_background = make_icon_background(color)
     # NOTE: border-style property needs to be set for QToolBar so the lineargradient works on GNOME desktop environment
-    return f"QToolBar{{spacing: 0px; background: {icon_background}; padding: 3px; border-style: solid;}}"
+    # return f"QToolBar{{spacing: 0px; background: {icon_background}; padding: 3px; border-style: solid;}}"
+    return ""
 
 
 def color_from_index(i, count, base_hue=0.0, saturation=1.0):
diff --git a/spinetoolbox/spine_db_editor/widgets/multi_spine_db_editor.py b/spinetoolbox/spine_db_editor/widgets/multi_spine_db_editor.py
index 8825874e5..c3400c12e 100644
--- a/spinetoolbox/spine_db_editor/widgets/multi_spine_db_editor.py
+++ b/spinetoolbox/spine_db_editor/widgets/multi_spine_db_editor.py
@@ -26,7 +26,6 @@
 from ...helpers import CharIconEngine, open_url
 from ...config import ONLINE_DOCUMENTATION_URL
 from ...widgets.settings_widget import SpineDBEditorSettingsWidget
-from ...config import MAINWINDOW_SS
 
 
 class MultiSpineDBEditor(MultiTabWindow):
@@ -44,7 +43,6 @@ def __init__(self, db_mngr, db_url_codenames=None):
         self.db_mngr.fetcher_waiting_over.connect(self._close_waiting_for_fetcher)
         self._waiting_box = None
         self.settings_form = SpineDBEditorSettingsWidget(self)
-        self.setStyleSheet(MAINWINDOW_SS)
         self.setWindowTitle("Spine DB Editor")
         self.setWindowIcon(QIcon(":/symbols/app.ico"))
         self.setStatusBar(_CustomStatusBar(self))
diff --git a/spinetoolbox/ui_main.py b/spinetoolbox/ui_main.py
index bcf6acb36..930d38e4d 100644
--- a/spinetoolbox/ui_main.py
+++ b/spinetoolbox/ui_main.py
@@ -57,6 +57,7 @@
     QVBoxLayout,
     QHBoxLayout,
 )
+import qdarktheme
 from spine_engine.load_project_items import load_item_specification_factories
 from spine_items.category import CATEGORIES, CATEGORY_DESCRIPTIONS
 from .project_item_icon import ProjectItemIcon
@@ -82,7 +83,7 @@
 from .spine_db_manager import SpineDBManager
 from .spine_db_editor.widgets.multi_spine_db_editor import MultiSpineDBEditor
 from .spine_engine_manager import make_engine_manager
-from .config import MAINWINDOW_SS, DEFAULT_WORK_DIR, ONLINE_DOCUMENTATION_URL
+from .config import DEFAULT_WORK_DIR, ONLINE_DOCUMENTATION_URL
 from .helpers import (
     create_dir,
     ensure_window_is_on_screen,
@@ -154,8 +155,6 @@ def __init__(self):
         self.ui.tabWidget_item_properties.installEventFilter(self.key_press_filter)
         self._share_item_edit_actions()
         self.ui.listView_console_executions.setModel(FilterExecutionModel(self))
-        # Set style sheets
-        self.setStyleSheet(MAINWINDOW_SS)
         # Class variables
         self.undo_stack = QUndoStack(self)
         self._item_categories = dict()
@@ -230,6 +229,7 @@ def __init__(self):
         self.set_work_directory()
         self._disable_project_actions()
         self.connect_signals()
+        qdarktheme.setup_theme("auto")
 
     def eventFilter(self, obj, ev):
         # Save/restore splitter states when hiding/showing execution lists
diff --git a/spinetoolbox/widgets/add_project_item_widget.py b/spinetoolbox/widgets/add_project_item_widget.py
index f07c9131b..c3ce87c7b 100644
--- a/spinetoolbox/widgets/add_project_item_widget.py
+++ b/spinetoolbox/widgets/add_project_item_widget.py
@@ -47,7 +47,7 @@ def __init__(self, toolbox, x, y, class_, spec=""):
         self.statusbar = QStatusBar(self)
         self.statusbar.setFixedHeight(20)
         self.statusbar.setSizeGripEnabled(False)
-        self.statusbar.setStyleSheet(STATUSBAR_SS)
+        # self.statusbar.setStyleSheet(STATUSBAR_SS)
         self.ui.horizontalLayout_statusbar_placeholder.addWidget(self.statusbar)
         # Init
         if toolbox.supports_specifications(class_.item_type()):
diff --git a/spinetoolbox/widgets/custom_qtextbrowser.py b/spinetoolbox/widgets/custom_qtextbrowser.py
index 32cc43f26..8ab50bb1b 100644
--- a/spinetoolbox/widgets/custom_qtextbrowser.py
+++ b/spinetoolbox/widgets/custom_qtextbrowser.py
@@ -20,7 +20,6 @@
 from PySide6.QtCore import Slot
 from PySide6.QtGui import QTextCursor, QFontDatabase, QTextBlockFormat, QTextFrameFormat, QBrush, QAction, QPalette
 from PySide6.QtWidgets import QTextBrowser, QMenu
-from ..config import TEXTBROWSER_SS
 from ..helpers import scrolling_to_bottom
 
 
@@ -37,7 +36,6 @@ def __init__(self, parent):
         super().__init__(parent=parent)
         self._toolbox = None
         self.document().setMaximumBlockCount(2000)
-        self.setStyleSheet(TEXTBROWSER_SS)
         self.setOpenExternalLinks(True)
         self.setOpenLinks(False)  # Don't try open file:/// links in the browser widget, we'll open them externally
         self._executions_menu = QMenu(self)
diff --git a/spinetoolbox/widgets/kernel_editor.py b/spinetoolbox/widgets/kernel_editor.py
index c459ee731..220bf9199 100644
--- a/spinetoolbox/widgets/kernel_editor.py
+++ b/spinetoolbox/widgets/kernel_editor.py
@@ -36,7 +36,6 @@
     ensure_window_is_on_screen,
     get_datetime,
 )
-from spinetoolbox.config import MAINWINDOW_SS
 from spinetoolbox.logger_interface import LoggerInterface
 from spinetoolbox.helpers import unique_name
 
@@ -74,7 +73,6 @@ def setup_dialog_style(self):
         This can be removed when SettingsWidget
         inherits stylesheet from ToolboxUI."""
         self.setWindowIcon(QIcon(":/symbols/app.ico"))
-        self.setStyleSheet(MAINWINDOW_SS)
 
     def connect_signals(self):
         """Connects signals to slots."""
diff --git a/spinetoolbox/widgets/multi_tab_spec_editor.py b/spinetoolbox/widgets/multi_tab_spec_editor.py
index 9b49d88b4..fc51fb0ab 100644
--- a/spinetoolbox/widgets/multi_tab_spec_editor.py
+++ b/spinetoolbox/widgets/multi_tab_spec_editor.py
@@ -25,7 +25,7 @@
 class MultiTabSpecEditor(MultiTabWindow):
     def __init__(self, toolbox, item_type):
         super().__init__(toolbox.qsettings(), f"{item_type}SpecEditor")
-        self.setStyleSheet(toolbox.styleSheet())
+        # self.setStyleSheet(toolbox.styleSheet())
         self._toolbox = toolbox
         self.item_type = item_type
         self.setWindowTitle(f"{item_type} specification editor".capitalize())
diff --git a/spinetoolbox/widgets/multi_tab_window.py b/spinetoolbox/widgets/multi_tab_window.py
index f9cb5ace0..04ea71089 100644
--- a/spinetoolbox/widgets/multi_tab_window.py
+++ b/spinetoolbox/widgets/multi_tab_window.py
@@ -40,7 +40,7 @@ def __init__(self, qsettings, settings_group):
         self.settings_group = settings_group
         self.tab_widget = QTabWidget(self)
         self.tab_bar = TabBarPlus(self)
-        self.tab_widget.setTabBar(self.tab_bar)
+        self.tab_widget.setTabBar(self.tab_bar)  # This sets mouseTracking on for self.tab_bar. Bug in pyqtdarktheme.
         self.setCentralWidget(self.tab_widget)
         self.setAttribute(Qt.WA_DeleteOnClose)
         self._hot_spot = None
@@ -508,6 +508,9 @@ def mousePressEvent(self, event):
 
     def mouseMoveEvent(self, event):
         """Detaches a tab either if the user moves beyond the limits of the tab bar, or if it's the only one."""
+        print(f"mouseTracking:{self.hasMouseTracking()} self._hot_spot_y:{self._hot_spot_y}")
+        if not self._hot_spot_y:  # This is a hacky effort to deal with the bug in pyqtdarktheme
+            return
         if self.count() > 0:
             self._plus_button.hide()
         if self.count() == 1: