diff --git a/.flake8 b/.flake8
index 276bd6d..5041c35 100644
--- a/.flake8
+++ b/.flake8
@@ -1,4 +1,8 @@
 [flake8]
 max-line-length = 120
 exclude = src/pyqulator/ui.py
+
 inline-quotes = "
+
+application-import-names = ui
+import-order-style = google
diff --git a/README.md b/README.md
index db246c2..9ea04e0 100644
--- a/README.md
+++ b/README.md
@@ -48,3 +48,8 @@ pyqulator
 *Unit converter*
 
 ![Screenshot](https://raw.githubusercontent.com/limafresh/pyqulator/main/screenshots/screenshot4.png)
+
+## Flake8
+```
+pip install flake8 flake8-quotes flake8-import-order flake8-builtins
+```
diff --git a/pyproject.toml b/pyproject.toml
index 5fcda42..2b57484 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pyqulator"
-version = "1.4.3"
+version = "1.5.0"
 dependencies = [
   "PyQt6>=6.4.2",
   "sympy>=1.13.3",
diff --git a/requirements-dev.txt b/requirements-dev.txt
deleted file mode 100644
index aaa6df1..0000000
--- a/requirements-dev.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-PyQt6>=6.4.2
-sympy>=1.13.3
-pyqt6-tools
-flake8
-flake8-quotes
diff --git a/src/pyqulator/main.py b/src/pyqulator/main.py
index 41fde39..b6dbe6f 100644
--- a/src/pyqulator/main.py
+++ b/src/pyqulator/main.py
@@ -1,10 +1,12 @@
+from os.path import dirname, join
 import sys
-from os.path import join, dirname
-from sympy import sympify, Rational, log, sin, cos, tan, exp, pi, E, sqrt
-from sympy.physics import units
-from PyQt6.QtWidgets import QApplication, QMainWindow, QMessageBox, QFileDialog
-from PyQt6.QtCore import QLocale, QTranslator, QSettings, Qt
+
+from PyQt6.QtCore import QLocale, QSettings, Qt, QTranslator
 from PyQt6.QtGui import QActionGroup, QIcon
+from PyQt6.QtWidgets import QApplication, QFileDialog, QMainWindow, QMessageBox
+from sympy import cos, E, exp, log, pi, Rational, sin, sqrt, sympify, tan
+from sympy.physics import units
+
 from .ui import Ui_MainWindow
 
 
@@ -454,6 +456,8 @@ def line_result_paste(self):
                 if char.isdigit() or char in ".":
                     filtered_text += char
         self.current_line_result.setText(filtered_text)
+        if self.current_line_result.text() == "":
+            self.clear_line_result()
 
     def line_top(self):
         while self.ui.horizontalLayout.count():
@@ -480,13 +484,14 @@ def line_down(self):
     # Show windows with info about program and Qt
     def show_about_program(self):
         self.about_msg = QMessageBox()
-        self.about_msg.setWindowTitle("About pyqulator")
+        self.about_msg.setWindowTitle("About Pyqulator")
         msg_text = """
-        pyqulator is a calculator written
-        in Python and PyQt 6.
-        Uses library: sympy.
-        Licensed under GNU GPL v3.
-        (c) limafresh, 2024
+        <p>Pyqulator is a calculator written<br>
+        in Python and PyQt 6.<br>
+        Uses library: sympy.<br>
+        Licensed under GNU GPL v3.<br>
+        (c) limafresh, 2024</p>
+        <p><a href="https://github.com/limafresh/pyqulator">Visit repository</a></p>
         """
         self.about_msg.setText(msg_text)
         icon = QIcon.fromTheme(u"accessories-calculator")