https://www.w3schools.com/cssref/css_selectors.asp
https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors
https://www.w3schools.com/css/css_pseudo_classes.asp
https://www.w3schools.com/css/css_pseudo_elements.asp
https://www.w3schools.com/css/css_howto.asp
https://www.w3schools.com/css/css_specificity.asp
https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS/Cascade_and_inheritance
https://www.w3schools.com/css/css_border.asp
https://www.w3schools.com/css/css_margin.asp
https://www.w3schools.com/css/css_padding.asp
http://guyroutledge.github.io/box-model/
https://www.w3schools.com/cssref/css_units.asp
https://www.w3schools.com/colors/colors_names.asp
https://color.adobe.com/create
https://www.w3schools.com/howto/howto_css_full_page.asp
https://www.w3schools.com/howto/howto_css_bg_change_scroll.asp




