Two ways to handle ltr/rtl on a page.

#css #ltr #rtl #righttoleft

When creating a multilingual web page you might need to handle languages written from right to left. This comes with some design issues.

First, you must add the dir attribute to your root (<html>) element. But the dir attribute alone cannot tackle everything. Sometimes you might have an image next to a paragraph, and a margin-left spacing them out. When you switch to the rtl language, you end up with a paragraph with a left margin, and an image stuck on the right side of it.

I will show you two ways that I have used to solve this problem.

Using CSS variables

The first way I thought was using CSS variables and some calculations to play with the left margin.

html[dir="ltr"] {
  --ltr: 1;
  --rtl: 0;
}

html[dir="rtl"] {
  --ltr: 0;
  --rtl: 1;
}

p {
  margin-left: calc(var(--ltr) * 20px);
  margin-right: calc(var(--rtl) * 20px);
}

What I do here is assign a number (0, 1) to the "boolean" variables --ltr and --rtl, declaring which direction is enabled. When the dir changes, the variables swap values. Then I calculate the left and right margins by multiplying the variables with the desired pixel value. So in ltr the left margin will be 1 × 20px = 20px, and the right margin will be 0 × 20px = 0. When we change to rtl the margins will swap values.

Using modern CSS

This is a clever way of setting the margins based on a boolean enabled/disabled variable. But, there is a better way by using modern CSS.

p {
  margin-inline-start: 20px;
}

And that's it. Way less code, and more elegant. It actually instructs the browser to add a 20px margin at the "start" of the x-axis. The start of the x-axis is relative to the direction set by the dir attribute. So in this case the browser will set a 20px left margin on ltr direction, and a 20px right margin on rtl direction.