"box-sizing" CSS property. Fairness somewhere near.
Bootstrap 4 has selected the initial Internet Explorer CSS box model. Oh my goodness, there is even "International box-sizing Awareness Day" out of there. "DOWN with big content-box, BORDER-BOX 4LIVE". It's such a boon for developers that here at CSS-Tricks we observe International Box-Sizing Awareness Day in February. Look, Bootstrap really uses it _reboot.scss // Reset the box-sizing // // Change from `box-sizing: content-box` to `border-box` so that when you add // `padding` or `border`s to an element, the overall declared `width` does not // change. For example, `width: 100px;` will always be `100px` despite the // `border: 10px solid red;` and `padding: 20px;`. // // Heads up! This reset may cause conflicts with some third-party widgets. For // recommendations on resolving such conflicts, see // https://getbootstrap.com/getting-started/#third-box-sizing. // // Credit: https://css-tricks.com/inheriting-box-sizing-probably-slightly-bett