Day 2: logical properties

posted on 27.09.2022

It’s time to get me up to speed with modern CSS. There’s so much new in CSS that I know too little about. To change that I’ve started #100DaysOfMoreOrLessModernCSS. Why more or less modern CSS? Because some topics will be about cutting-edge features, while other stuff has been around for quite a while already, but I just have little to no experience with it.

Logical properties are a new way of working with directions and dimensions, one that allows you to control layout through logical, rather than physical mappings. This is especially useful, if you’re dealing with websites that are presented in different languages and writing modes, like right-to-left.

Physical properties

We're used to working with physical properties like margin-right, top, or border-left. In the following example, list items are positioned horizontally, and each item has a right margin.

HTML:

<ul>
  <li>One</li>
  <li>Two</li>
  <li>Three</li>
</ul>

CSS:

li {
  background-color: #6befef;
  margin-right: 2rem;
}

When you change the reading direction from right to left, you'd expect the first item to be positioned at the right edge of its parent, but it's not because physical properties don't change with the reading direction.

HTML:

<ul dir="rtl">
  <li>One</li>
  <li>Two</li>
  <li>Three</li>
</ul>

Logical properties

Using logical properties, “One” is at the very right in right-to-left languages because logical properties don't work with the concept of top and bottom or left and right, but start and end, which switches depending on the writing mode.

HTML:

li {
  margin-inline-end: 2rem;
}

See on CodePen

Further reading

• RTL Styling 101
• Day 3: logical property shorthands
• Day 31: logical border properties
• Day 44: logical floating and clearing

Overview: 100 Days Of More Or Less Modern CSS