Added CSS file for graph

src/main/java/com/application/DB/Constants.java

...main/java/com/application/GUI/LineChartFunctionality.java

...ces/com.application/DataProcessing/NonlinearRegression.py

src/main/resources/com.application/GUI/graphStyles.css

...sources/com.application/GUI/graphical_user_interface.fxml

...ses/com.application/DataProcessing/NonlinearRegression.py

target/classes/com.application/GUI/graphStyles.css

...classes/com.application/GUI/graphical_user_interface.fxml

target/classes/com/application/DB/Constants.class

target/classes/com/application/DB/DB.class

.../classes/com/application/GUI/LineChartFunctionality.class