generated at
CSSのBox Model

https://www.w3schools.com/css/css_boxmodel.asp
https://www.billionwallet.com/homepage/boxmodel.html
https://nulab.com/ja/blog/nulab/css-basics-for-engineer-boxmodel/
https://developer.mozilla.org/ja/docs/Learn/CSS/Building_blocks/The_box_model
/mrsekut-book-486246517X/018: 1-01 ボックス
https://developer.mozilla.org/ja/docs/Web/CSS/CSS_Box_Model/Introduction_to_the_CSS_box_model
https://azukiazusa.dev/blog/css-box-model