Remove hardcode for button size

src/gui/mainmenu.cpp

@@ -6,13 +6,15 @@ MainMenu::MainMenu(sf::RenderWindow& game_window, Callbacks&& callbacks) :
     _buttons(std::make_shared<Group>()),
     _game_window(game_window)
 {
+    const float window_width = game_window.getSize().x;
+    const float window_height = game_window.getSize().y;
+
     std::shared_ptr<Button> button_start = std::make_shared<Button>("Start");
-    button_start->setRect(sf::FloatRect(140, 140, 500, 100));
+    button_start->setRect(sf::FloatRect(window_width / 3., window_height / 7. * 2, window_width / 3., window_height / 7.));
     button_start->setCallback(callbacks.onAppendGameState);
 
     std::shared_ptr<Button> button_exit = std::make_shared<Button>("Exit");
-    button_exit->setRect(sf::FloatRect(140, 140, 400, 100));
-    button_exit->setPosition({240, 340});
+    button_exit->setRect(sf::FloatRect(window_width / 3., window_height / 7. * 4, window_width / 3., window_height / 7.));
     button_exit->setCallback([&]()
     {
         _game_window.close();

src/gui/widgets/button.cpp

@@ -53,7 +53,7 @@ void Button::draw(sf::RenderTarget& target, sf::RenderStates states) const
 void Button::setRect(const sf::FloatRect& rect)
 {
     _button_content.setPosition(rect.left, rect.top);
-    _button_content.setSize({rect.width - rect.left, rect.height - rect.top});
+    _button_content.setSize({rect.width, rect.height});
 }
 
 void Button::setPosition(const sf::Vector2f &position)