Removed unused style sheet

resources/chat_window.ui

@@ -711,21 +711,6 @@ QToolButton:hover {
        </layout>
       </widget>
       <widget class="QTabWidget" name="tab_widget">
-       <property name="styleSheet">
-        <string notr="true">noQTabWidget::pane { background: palette(light); border: none; }
-noQTabWidget::tab-bar { left: 5px; background: palette(light); }
-noQTabBar { background: palette(dark); }
-noQTabBar::tab {
-	padding: 4px 2px 2px 2px;
-	background: palette(mid);
-	border: 2px solid palette(dark);
-	border-top: none;
-	border-bottom-left-radius: 4px;
-	border-bottom-right-radius: 4px;
-}
-noQTabBar::tab:selected { background: palette(light); }
-</string>
-       </property>
        <property name="tabPosition">
         <enum>QTabWidget::South</enum>
        </property>