https://www.w3schools.com:443/css/css_boxmodel.asp
CSS Box Model
Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML...
css box model
https://www.codecademy.com/learn/learn-css-box-model-and-layout
Learn CSS: Box Model and Layout | Codecademy
Use the box model to fine tune display and positioning of HTML elements.
css box modellearnlayoutcodecademy
https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Box_model
CSS box model - CSS | MDN
The CSS box model module defines the margin and padding properties, which along with the height, width and border properties, make up the CSS box model.
css box modelmdn