Line height set with !important in style attributes must be at least 1.5.

When line-height is set with !important in a style attribute and the value is less than 1.5 times the font size, users cannot override the line spacing with their own stylesheets or browser extensions. This creates a problem because many people need to adjust text spacing to read content comfortably.

WCAG Success Criterion 1.4.12 (Text Spacing, Level AA) requires that content and functionality remain intact when users adjust certain text spacing properties, including line height. The expectation is that users can set line height to at least 1.5 times the font size without losing content or breaking functionality. When authors use !important in an inline style attribute with a line height below that threshold, they block this adjustment.

The reason inline !important styles are specifically problematic has to do with how CSS cascade resolution works. A style attribute already has higher specificity than any selector in a stylesheet. Adding !important on top of that makes the declaration nearly impossible to override from the author origin. Assistive technologies and browser extensions that inject custom stylesheets operate at the author origin level, so they cannot override an inline !important declaration. Only user-origin or user-agent-origin !important styles can win the cascade over it, and not all assistive technologies can set styles at those origins.

People affected by this issue include users with dyslexia, cognitive disabilities, and low vision. Tight line spacing causes lines of text to blur together, making it harder to track from one line to the next. Users who adjust text spacing as a reading accommodation are directly blocked when inline !important prevents their overrides from taking effect.

How to fix it

There are two straightforward fixes:

1. Increase the line-height value to at least 1.5 (relative to the font size). If the value already meets or exceeds 1.5, the !important declaration is acceptable because the user's minimum need is already satisfied.
2. Remove !important from the line-height declaration in the style attribute. This allows user stylesheets and assistive technology overrides to take effect through normal cascade resolution.

If the line-height is defined in an external or embedded stylesheet rather than a style attribute, this rule does not apply, because stylesheet-based declarations can be overridden by other author-origin styles with equal or higher specificity.

This rule only applies to elements that contain visible text with at least one soft wrap break (i.e., text that wraps across multiple lines). Single-line text is not affected because line height has no visual impact when there is only one line.

Examples

Incorrect: line height below 1.5 with !important

<p style="line-height: 1.2 !important;">
  This paragraph has tight line spacing that users cannot override.
  The text wraps to multiple lines, making the insufficient
  line height a readability problem.
</p>

The line-height of 1.2 is below the 1.5 minimum, and !important prevents user overrides.

Correct: line height at 1.5 or above with !important

<p style="line-height: 1.5 !important;">
  This paragraph meets the minimum line height threshold.
  Even though !important is used, the spacing is already
  sufficient for readability.
</p>

Because the value is at least 1.5, the requirement is satisfied even with !important.

Correct: removing !important

<p style="line-height: 1.2;">
  This paragraph has a line height below 1.5, but without
  !important, users and assistive technologies can override
  it with their own stylesheets.
</p>

Without !important, the declaration can be overridden through the normal cascade.

Correct: using an external stylesheet instead

<style>
  .tight-text {
    line-height: 1.2;
  }
</style>
<p class="tight-text">
  This paragraph gets its line height from a stylesheet rule,
  not an inline style attribute. Other author-origin styles
  with equal or greater specificity can override it.
</p>

Stylesheet-based declarations are easier to override than inline styles, so this approach does not trigger the rule.

Learn more:

W3C Reference

Understanding Success Criterion 1.4.12: Text Spacing

→

W3C Reference

CSS Techniques for WCAG 2.1 - C21: Specifying line spacing in CSS

→