diff --git a/src/main.cpp b/src/main.cpp
index 9b6054f..05ab4ef 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -31,6 +31,9 @@ int main(int argc, char *argv[])
     QString languageFile = settings->value("extPath").toString();
     QString languageName = settings->value("name").toString();
     settings->endGroup();
+    settings->beginGroup("UI");
+    QString theme = settings->value("Theme_Name").toString();
+    settings->endGroup();
     if(languageName == "")
     {
         if(Util::chooseLanguage(settings, &w))
@@ -55,7 +58,35 @@ int main(int argc, char *argv[])
         a.installTranslator(translator);
     else
         QMessageBox::information(&w, "Error", "Can't load " + languageFile + " as translation file.");
+
+    QFile* themeFile = new QFile();
+    QTextStream* themeStream = new QTextStream();
+    QString qssString = a.styleSheet(); // default behavior
+    if(theme == "(none)")
+        ;
+    else if(theme == "qdss_dark")
+    {
+        themeFile->setFileName(":/qdarkstyle/dark/darkstyle.qss");
+        themeFile->open(QFile::ReadOnly | QFile::Text);
+        themeStream->setDevice(themeFile);
+        qssString = themeStream->readAll();
+    }
+    else if(theme == "qdss_light")
+    {
+        themeFile->setFileName(":/qdarkstyle/light/lightstyle.qss");
+        themeFile->open(QFile::ReadOnly | QFile::Text);
+        themeStream->setDevice(themeFile);
+        qssString = themeStream->readAll();
+    }
+    a.setStyleSheet(qssString);
+    delete themeFile;
+    delete themeStream;
+    themeFile = nullptr;
+    themeStream = nullptr;
+
     delete settings;
+    settings = nullptr;
+
     w.initUI();
     w.show();
     return a.exec();
diff --git a/src/ui/mainwindow.cpp b/src/ui/mainwindow.cpp
index 5de7884..c756b3b 100644
--- a/src/ui/mainwindow.cpp
+++ b/src/ui/mainwindow.cpp
@@ -528,18 +528,6 @@ void MainWindow::on_MF_trailerDecoderButton_clicked()
     decDialog->show();
 }
 
-void MainWindow::on_MF_fontButton_clicked()
-{
-    bool isOK = false;
-    QFont font = QFontDialog::getFont(&isOK, ui->MF_keyWidget->font(), this, tr("Plz select the font of data widget and key widget"));
-
-    if(isOK)
-    {
-        ui->MF_keyWidget->setFont(font);
-        ui->MF_dataWidget->setFont(font);
-    }
-}
-
 void MainWindow::on_MF_dataWidget_itemChanged(QTableWidgetItem *item)
 {
     ui->MF_dataWidget->blockSignals(true);
@@ -1076,6 +1064,10 @@ void MainWindow::uiInit()
     ui->MF_keyWidget->installEventFilter(this);
     ui->MF_dataWidget->installEventFilter(this);
 
+    ui->Set_UI_Theme_nameBox->addItem(tr("(None)"), "(none)");
+    ui->Set_UI_Theme_nameBox->addItem(tr("Dark"), "qdss_dark");
+    ui->Set_UI_Theme_nameBox->addItem(tr("Light"), "qdss_light");
+
     settings->beginGroup("UI_grpbox_preference");
 
     QStringList boxNames = settings->allKeys();
@@ -1147,6 +1139,49 @@ void MainWindow::uiInit()
     ui->Set_Client_configFileBox->blockSignals(false);
     on_Set_Client_configFileBox_currentIndexChanged(ui->Set_Client_configFileBox->currentIndex());
 
+    settings->beginGroup("UI");
+    ui->Set_UI_Opacity_Box->setValue(settings->value("Opacity", 100).toInt());
+    int themeId = ui->Set_UI_Theme_nameBox->findData(settings->value("Theme_Name", "(none)").toString());
+    ui->Set_UI_Theme_nameBox->setCurrentIndex((themeId == -1) ? 0 : themeId);
+
+    // QApplication::font() might return wrong result
+    // If fonts are not specified in config file, don't touch them.
+    QString tmpFontName;
+    int tmpFontSize;
+    bool fontValid = false, dataFontValid = false, CMDFontValid = false;
+    tmpFontName = settings->value("Font_Name", "").toString();
+    tmpFontSize = settings->value("Font_Size", -1).toInt();
+    if(!tmpFontName.isEmpty() && tmpFontSize != -1 && tmpFontName == QFont(tmpFontName).family())
+    {
+        ui->Set_UI_Font_nameBox->setCurrentFont(QFont(tmpFontName));
+        ui->Set_UI_Font_sizeBox->setValue(tmpFontSize);
+        fontValid = true;
+    }
+    // The default values should be the same as MF_dataWidget's and MF_keyWidget's.
+    tmpFontName = settings->value("DataFont_Name", "Consolas").toString();
+    tmpFontSize = settings->value("DataFont_Size", 12).toInt();
+    if(!tmpFontName.isEmpty() && tmpFontSize != -1 && tmpFontName == QFont(tmpFontName).family())
+    {
+        ui->Set_UI_DataFont_nameBox->setCurrentFont(QFont(tmpFontName));
+        ui->Set_UI_DataFont_sizeBox->setValue(tmpFontSize);
+        dataFontValid = true;
+    }
+    tmpFontName = settings->value("CMDFont_Name", "").toString();
+    tmpFontSize = settings->value("CMDFont_Size", -1).toInt();
+    if(!tmpFontName.isEmpty() && tmpFontSize != -1 && tmpFontName == QFont(tmpFontName).family())
+    {
+        ui->Set_UI_CMDFont_nameBox->setCurrentFont(QFont(tmpFontName));
+        ui->Set_UI_CMDFont_sizeBox->setValue(tmpFontSize);
+        CMDFontValid = true;
+    }
+    settings->endGroup();
+
+    if(fontValid)
+        on_Set_UI_Font_setButton_clicked();
+    if(dataFontValid)
+        on_Set_UI_DataFont_setButton_clicked();
+    if(CMDFontValid)
+        on_Set_UI_CMDFont_setButton_clicked();
 
     ui->MF_RW_keyTypeBox->addItem("A", Mifare::KEY_A);
     ui->MF_RW_keyTypeBox->addItem("B", Mifare::KEY_B);
@@ -1184,6 +1219,8 @@ void MainWindow::signalInit()
     connect(ui->MF_sniffGroupBox, &QGroupBox::clicked, this, &MainWindow::on_GroupBox_clicked);
 
     connect(stopButton, &QPushButton::clicked, this, &MainWindow::on_stopButton_clicked);
+
+    connect(ui->Set_UI_Opacity_slider, &QSlider::valueChanged, ui->Set_UI_Opacity_Box, &QSpinBox::setValue);
 }
 
 void MainWindow::setStatusBar(QLabel * target, const QString& text)
@@ -1496,3 +1533,63 @@ void MainWindow::on_Set_Client_configFileBox_currentIndexChanged(int index)
     settings->endGroup();
 }
 
+
+void MainWindow::on_Set_UI_Opacity_Box_valueChanged(int arg1)
+{
+    ui->Set_UI_Opacity_slider->blockSignals(true);
+    ui->Set_UI_Opacity_slider->setValue(arg1);
+    setWindowOpacity(arg1 / 100.0);
+    settings->beginGroup("UI");
+    settings->setValue("Opacity", ui->Set_UI_Opacity_Box->value());
+    settings->endGroup();
+    ui->Set_UI_Opacity_slider->blockSignals(false);
+}
+
+
+void MainWindow::on_Set_UI_Theme_setButton_clicked()
+{
+    settings->beginGroup("UI");
+    settings->setValue("Theme_Name", ui->Set_UI_Theme_nameBox->currentData().toString());
+    settings->endGroup();
+}
+
+
+void MainWindow::on_Set_UI_Font_setButton_clicked()
+{
+    QFont font = ui->Set_UI_Font_nameBox->currentFont();
+    font.setPointSize(ui->Set_UI_Font_sizeBox->value());
+    QApplication::setFont(font, "QWidget");
+
+    settings->beginGroup("UI");
+    settings->setValue("Font_Name", ui->Set_UI_Font_nameBox->currentFont().family());
+    settings->setValue("Font_Size", ui->Set_UI_Font_sizeBox->value());
+    settings->endGroup();
+}
+
+
+void MainWindow::on_Set_UI_DataFont_setButton_clicked()
+{
+    QFont font = ui->Set_UI_DataFont_nameBox->currentFont();
+    font.setPointSize(ui->Set_UI_DataFont_sizeBox->value());
+    ui->MF_dataWidget->setFont(font);
+    ui->MF_keyWidget->setFont(font);
+
+    settings->beginGroup("UI");
+    settings->setValue("DataFont_Name", ui->Set_UI_DataFont_nameBox->currentFont().family());
+    settings->setValue("DataFont_Size", ui->Set_UI_DataFont_sizeBox->value());
+    settings->endGroup();
+}
+
+
+void MainWindow::on_Set_UI_CMDFont_setButton_clicked()
+{
+    QFont font = ui->Set_UI_CMDFont_nameBox->currentFont();
+    font.setPointSize(ui->Set_UI_CMDFont_sizeBox->value());
+    ui->Raw_outputEdit->setFont(font);
+
+    settings->beginGroup("UI");
+    settings->setValue("CMDFont_Name", ui->Set_UI_CMDFont_nameBox->currentFont().family());
+    settings->setValue("CMDFont_Size", ui->Set_UI_CMDFont_sizeBox->value());
+    settings->endGroup();
+}
+
diff --git a/src/ui/mainwindow.h b/src/ui/mainwindow.h
index 82cd37d..b66915b 100644
--- a/src/ui/mainwindow.h
+++ b/src/ui/mainwindow.h
@@ -128,8 +128,6 @@ private slots:
 
     void on_MF_keyWidget_itemChanged(QTableWidgetItem *item);
 
-    void on_MF_fontButton_clicked();
-
     void on_MF_UID_wipeButton_clicked();
 
     void on_MF_UID_aboutUIDButton_clicked();
@@ -212,6 +210,16 @@ private slots:
 
     void on_Set_Client_configFileBox_currentIndexChanged(int index);
 
+    void on_Set_UI_Opacity_Box_valueChanged(int arg1);
+
+    void on_Set_UI_Theme_setButton_clicked();
+
+    void on_Set_UI_Font_setButton_clicked();
+
+    void on_Set_UI_DataFont_setButton_clicked();
+
+    void on_Set_UI_CMDFont_setButton_clicked();
+
 private:
     Ui::MainWindow* ui;
     QButtonGroup* MFCardTypeBtnGroup;
diff --git a/src/ui/mainwindow.ui b/src/ui/mainwindow.ui
index b94e633..ca2a943 100644
--- a/src/ui/mainwindow.ui
+++ b/src/ui/mainwindow.ui
@@ -315,19 +315,6 @@
               </property>
              </widget>
             </item>
-            <item>
-             <widget class="QPushButton" name="MF_fontButton">
-              <property name="minimumSize">
-               <size>
-                <width>40</width>
-                <height>0</height>
-               </size>
-              </property>
-              <property name="text">
-               <string>Set Fonts</string>
-              </property>
-             </widget>
-            </item>
             <item>
              <spacer name="verticalSpacer_2">
               <property name="orientation">