diff --git a/app/airshare/buffer.py b/app/airshare/buffer.py
index ad9463e..8cd59db 100644
--- a/app/airshare/buffer.py
+++ b/app/airshare/buffer.py
@@ -27,8 +27,8 @@ from core.buffer import Buffer
 import qrcode
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, False, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(0, 0, 0, 255))
 
         self.add_widget(AirShareWidget(url, QColor(0, 0, 0, 255)))
 
diff --git a/app/browser/buffer.py b/app/browser/buffer.py
index 5a36e26..c92506f 100644
--- a/app/browser/buffer.py
+++ b/app/browser/buffer.py
@@ -26,8 +26,8 @@ from core.utils import touch
 import os
 
 class AppBuffer(BrowserBuffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         self.config_dir = config_dir
 
diff --git a/app/camera/buffer.py b/app/camera/buffer.py
index 093d878..123e591 100644
--- a/app/camera/buffer.py
+++ b/app/camera/buffer.py
@@ -32,8 +32,8 @@ import time
 import os
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, True, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, True, QColor(0, 0, 0, 255))
         self.add_widget(CameraWidget(QColor(0, 0, 0, 255)))
 
     def all_views_hide(self):
diff --git a/app/demo/buffer.py b/app/demo/buffer.py
index 2cc1dd2..03bdb65 100644
--- a/app/demo/buffer.py
+++ b/app/demo/buffer.py
@@ -24,8 +24,8 @@ from PyQt5.QtWidgets import QPushButton
 from core.buffer import Buffer
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, True, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, True, QColor(0, 0, 0, 255))
 
         self.add_widget(QPushButton("Hello, EAF hacker, it's working!!!"))
         self.buffer_widget.setStyleSheet("font-size: 100px")
diff --git a/app/file-receiver/buffer.py b/app/file-receiver/buffer.py
index 3d90519..18fc462 100644
--- a/app/file-receiver/buffer.py
+++ b/app/file-receiver/buffer.py
@@ -41,8 +41,8 @@ import urllib
 from core.buffer import Buffer
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, argument, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, argument, emacs_var_dict, module_path, False, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, argument, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, argument, emacs_var_dict, module_path, is_dark_mode, False, QColor(0, 0, 0, 255))
 
         self.add_widget(FileUploaderWidget(url, QColor(0, 0, 0, 255)))
 
diff --git a/app/file-sender/buffer.py b/app/file-sender/buffer.py
index bd02a4f..b8df7f3 100644
--- a/app/file-sender/buffer.py
+++ b/app/file-sender/buffer.py
@@ -34,8 +34,8 @@ import threading
 import socket
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, False, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(0, 0, 0, 255))
 
         self.add_widget(FileTransferWidget(url, QColor(0, 0, 0, 255)))
 
diff --git a/app/image-viewer/buffer.py b/app/image-viewer/buffer.py
index 4baeb76..928c68c 100644
--- a/app/image-viewer/buffer.py
+++ b/app/image-viewer/buffer.py
@@ -27,8 +27,8 @@ from pathlib import Path
 import os
 
 class AppBuffer(BrowserBuffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         self.load_image(url)
 
diff --git a/app/js-video-player/buffer.py b/app/js-video-player/buffer.py
index 0a480aa..30b1c11 100644
--- a/app/js-video-player/buffer.py
+++ b/app/js-video-player/buffer.py
@@ -32,8 +32,8 @@ class AppBuffer(BrowserBuffer):
 
     export_org_json = QtCore.pyqtSignal(str, str)
 
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         self.url = url
         index_file = "file://" + (os.path.join(os.path.dirname(__file__), "index.html"))
diff --git a/app/markdown-previewer/buffer.py b/app/markdown-previewer/buffer.py
index 7e10271..15eb09f 100644
--- a/app/markdown-previewer/buffer.py
+++ b/app/markdown-previewer/buffer.py
@@ -28,8 +28,8 @@ import subprocess
 import threading
 
 class AppBuffer(BrowserBuffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         # Get free port to render markdown.
         self.port = get_free_port()
diff --git a/app/mermaid/buffer.py b/app/mermaid/buffer.py
index 4907ccf..eda67a2 100644
--- a/app/mermaid/buffer.py
+++ b/app/mermaid/buffer.py
@@ -36,8 +36,8 @@ class AppBuffer(BrowserBuffer):
 
     update_content = QtCore.pyqtSignal()
 
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         self.url = url
         self.render()
diff --git a/app/mindmap/buffer.py b/app/mindmap/buffer.py
index e6cefa5..1716572 100644
--- a/app/mindmap/buffer.py
+++ b/app/mindmap/buffer.py
@@ -32,8 +32,8 @@ class AppBuffer(BrowserBuffer):
 
     export_org_json = QtCore.pyqtSignal(str, str)
 
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         self.url = url
         index_file = "file://" + (os.path.join(os.path.dirname(__file__), "index.html"))
@@ -72,7 +72,7 @@ class AppBuffer(BrowserBuffer):
             self.buffer_widget.eval_js("init_root_node();")
 
         color = "#FFFFFF"
-        if self.emacs_var_dict["eaf-mindmap-dark-mode"] == "true":
+        if self.emacs_var_dict["eaf-mindmap-dark-mode"] == "true" or (self.emacs_var_dict["eaf-mindmap-dark-mode"] == "" and self.is_dark_mode):
             color = "#242525"
         self.buffer_widget.eval_js("init_background('{}');".format(color))
 
diff --git a/app/org-previewer/buffer.py b/app/org-previewer/buffer.py
index 4c52adb..9790e99 100644
--- a/app/org-previewer/buffer.py
+++ b/app/org-previewer/buffer.py
@@ -25,8 +25,8 @@ from core.browser import BrowserBuffer
 import os
 
 class AppBuffer(BrowserBuffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         self.url = url
 
diff --git a/app/pdf-viewer/buffer.py b/app/pdf-viewer/buffer.py
index 1a1333a..0026e08 100755
--- a/app/pdf-viewer/buffer.py
+++ b/app/pdf-viewer/buffer.py
@@ -34,8 +34,8 @@ import os
 import hashlib
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, False, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(0, 0, 0, 255))
 
         self.delete_temp_file = arguments == "temp_pdf_file"
         self.add_widget(PdfViewerWidget(url, config_dir, QColor(0, 0, 0, 255), buffer_id, emacs_var_dict))
diff --git a/app/rss-reader/buffer.py b/app/rss-reader/buffer.py
index 1c0d4ee..41ecd06 100644
--- a/app/rss-reader/buffer.py
+++ b/app/rss-reader/buffer.py
@@ -31,8 +31,8 @@ import json
 import os
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, True, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, True, QColor(0, 0, 0, 255))
 
         self.add_widget(RSSReaderWidget(config_dir))
 
diff --git a/app/terminal/buffer.py b/app/terminal/buffer.py
index c7f8121..80b643c 100644
--- a/app/terminal/buffer.py
+++ b/app/terminal/buffer.py
@@ -30,8 +30,8 @@ import threading
 import getpass
 
 class AppBuffer(BrowserBuffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, False, QColor(255, 255, 255, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        BrowserBuffer.__init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, False, QColor(255, 255, 255, 255))
 
         # Get free port to render markdown.
         self.port = get_free_port()
diff --git a/app/video-player/buffer.py b/app/video-player/buffer.py
index 5c81ac6..50079e9 100644
--- a/app/video-player/buffer.py
+++ b/app/video-player/buffer.py
@@ -27,8 +27,8 @@ from PyQt5.QtWidgets import QWidget, QGraphicsScene, QGraphicsView, QVBoxLayout
 from core.buffer import Buffer
 
 class AppBuffer(Buffer):
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, True, QColor(0, 0, 0, 255))
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, True, QColor(0, 0, 0, 255))
 
         self.add_widget(VideoPlayerWidget())
         self.buffer_widget.play(url)
diff --git a/core/browser.py b/core/browser.py
index 0e89b44..83f28a1 100644
--- a/core/browser.py
+++ b/core/browser.py
@@ -369,8 +369,8 @@ class BrowserBuffer(Buffer):
     enter_fullscreen_request = QtCore.pyqtSignal()
     exit_fullscreen_request = QtCore.pyqtSignal()
 
-    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, fit_to_view, background_color):
-        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, fit_to_view, background_color)
+    def __init__(self, buffer_id, url, config_dir, arguments, emacs_var_dict, module_path, is_dark_mode, fit_to_view, background_color):
+        Buffer.__init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, fit_to_view, background_color)
 
         self.add_widget(BrowserView(config_dir))
 
@@ -472,7 +472,9 @@ class BrowserBuffer(Buffer):
 
     def dark_mode_is_enable(self):
         module_name = self.module_path.split(".")[1]
-        return self.emacs_var_dict["eaf-browser-dark-mode"] == "true" and module_name in ["browser"] and self.url != "devtools://devtools/bundled/devtools_app.html"
+        return (self.emacs_var_dict["eaf-browser-dark-mode"] == "true" or (self.emacs_var_dict["eaf-browser-dark-mode"] == "" and self.is_dark_mode)) \
+            and module_name in ["browser"] \
+            and self.url != "devtools://devtools/bundled/devtools_app.html"
 
     def init_background_color(self):
         if self.dark_mode_is_enable():
diff --git a/core/buffer.py b/core/buffer.py
index a1e54fe..35aae9e 100755
--- a/core/buffer.py
+++ b/core/buffer.py
@@ -160,7 +160,7 @@ class Buffer(QGraphicsScene):
     goto_right_tab = QtCore.pyqtSignal()
     aspect_ratio_change = QtCore.pyqtSignal()
 
-    def __init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, fit_to_view, background_color):
+    def __init__(self, buffer_id, url, arguments, emacs_var_dict, module_path, is_dark_mode, fit_to_view, background_color):
         super(QGraphicsScene, self).__init__()
 
         self.buffer_id = buffer_id
@@ -171,6 +171,7 @@ class Buffer(QGraphicsScene):
         self.fit_to_view = fit_to_view
         self.background_color = background_color
         self.setBackgroundBrush(QBrush(self.background_color))
+        self.is_dark_mode = is_dark_mode
 
         self.buffer_widget = None
 
diff --git a/eaf.el b/eaf.el
index cd60170..5210549 100644
--- a/eaf.el
+++ b/eaf.el
@@ -240,14 +240,14 @@ It must defined at `eaf-browser-search-engines'."
     (eaf-browser-remember-history . "true")
     (eaf-browser-default-zoom . "1.0")
     (eaf-browser-blank-page-url . "https://www.google.com")
-    (eaf-browser-dark-mode . "false")
     (eaf-browser-scroll-behavior . "auto")
     (eaf-browser-download-path . "~/Downloads")
     (eaf-browser-aria2-proxy-host . "")
     (eaf-browser-aria2-proxy-port . "")
-    (eaf-marker-letters . "ASDFHJKLWEOPCNM")
-    (eaf-mindmap-dark-mode . "false")
+    (eaf-browser-dark-mode . "")
+    (eaf-mindmap-dark-mode . "")
     (eaf-mindmap-save-path . "~/Documents")
+    (eaf-marker-letters . "ASDFHJKLWEOPCNM")
     )
   "The alist storing user-defined variables that's shared with EAF Python side.
 
@@ -791,7 +791,8 @@ For now only EAF browser app is supported."
                      (list eaf-python-file)
                      (eaf-get-render-size)
                      (list eaf-proxy-host eaf-proxy-port eaf-proxy-type eaf-config-location)
-                     (list (eaf-serialization-var-list))))
+                     (list (eaf-serialization-var-list))
+                     (list (eaf-is-dark-theme))))
           (gdb-args (list "-batch" "-ex" "run" "-ex" "bt" "--args" eaf-python-command)))
       (setq eaf-process
             (if eaf-enable-debug
@@ -1775,6 +1776,11 @@ Make sure that your smartphone is connected to the same WiFi network as this com
                          )))))
     (message "Please install libreoffice to convert office file to pdf.")))
 
+(defun eaf-is-dark-theme ()
+  (if (eq (frame-parameter nil 'background-mode) 'light)
+      "false"
+    "true"))
+
 (dbus-register-signal
  :session "com.lazycat.eaf" "/com/lazycat/eaf"
  "com.lazycat.eaf" "edit_focus_text"
diff --git a/eaf.py b/eaf.py
index fef965f..fe26bb7 100755
--- a/eaf.py
+++ b/eaf.py
@@ -39,14 +39,14 @@ EAF_OBJECT_NAME = "/com/lazycat/eaf"
 
 class EAF(dbus.service.Object):
     def __init__(self, args):
-        global emacs_width, emacs_height, eaf_config_dir, proxy_string
+        global emacs_width, emacs_height, eaf_config_dir, proxy_string, is_dark_mode
 
         dbus.service.Object.__init__(
             self,
             dbus.service.BusName(EAF_DBUS_NAME, bus=dbus.SessionBus()),
             EAF_OBJECT_NAME)
 
-        (emacs_width, emacs_height, proxy_host, proxy_port, proxy_type, config_dir, var_dict_string) = args
+        (emacs_width, emacs_height, proxy_host, proxy_port, proxy_type, config_dir, var_dict_string, is_dark_mode) = args
         emacs_width = int(emacs_width)
         emacs_height = int(emacs_height)
         eaf_config_dir = os.path.expanduser(config_dir)
@@ -139,11 +139,11 @@ class EAF(dbus.service.Object):
             return "EAF: Something went wrong when trying to import {0}".format(module_path)
 
     def create_buffer(self, buffer_id, url, module_path, arguments):
-        global emacs_width, emacs_height, eaf_config_dir, proxy_string
+        global emacs_width, emacs_height, eaf_config_dir, proxy_string, is_dark_mode
 
         # Create application buffer.
         module = importlib.import_module(module_path)
-        app_buffer = module.AppBuffer(buffer_id, url, eaf_config_dir, arguments, self.emacs_var_dict, module_path)
+        app_buffer = module.AppBuffer(buffer_id, url, eaf_config_dir, arguments, self.emacs_var_dict, module_path, bool(is_dark_mode))
 
         # Add buffer to buffer dict.
         self.buffer_dict[buffer_id] = app_buffer