:read-only and :read-write are pseudo-classes used to style elements based on whether they are editable. 1.:read-only is used for non-editable elements such as input boxes with readonly attributes; 2.:read-write is used for editable elements such as normal text boxes and contenteditable areas; 3. They are suitable for form design, dynamic interfaces and conditional styles, but they need to be used with HTML attributes to ensure correct functions; 4. Modern browsers have good support, but early IE versions may not be compatible.

In CSS, :read-only and :read-write are pseudo-classes that let you style elements based on whether they're editable or not. They might not be as commonly used as :hover or :focus , but they come in handy when dealing with form inputs and contenteditable elements.

When to Use :read-only

This pseudo-class targets elements that are not editable by the user. That includes input fields with the readonly attribute, or elements like <div> or <code><span></span> that aren't meant for editing.

For example:

 <input type="text" value="I&#39;m read-only" readonly>

You can style it like this:

 input:read-only {
  background-color: #f0f0f0;
  border: 1px solid #ccc;
}

It's useful when you want to visually distinguish non-editable fields from regular ones — maybe to make them look more static or grayed out.

Note: Just because an element is styled with :read-only , it doesn't mean it's actually locked — always use the readonly attribute in HTML for real behavior control.

When to Use :read-write

On the flip side, :read-write applies to elements users can edit. This includes standard text inputs, textareas, and even elements with the contenteditable attribute set.

Here's a basic example:

 <textarea>I&#39;m editable</textarea>
<div contenteditable="true">Edit me too!</div>

And the corresponding CSS:

 :read-write {
  border: 2px dashed #4caf50;
}

This selector is especially helpful if you want to apply consistent styles across all editable areas — say, adding a subtle highlight or different padding.

Also, keep in mind that even password fields ( <input type="password"> ) are considered :read-write , so your styles will apply there too unless you specifically exclude them.

Practical Use Cases

Here are a few places where these pseudo-classes can really shine:

• Form design: Highlight editable vs non-editable fields to improve UX.
• Dynamic interfaces: Style contenteditable regions differently to signal interaction.
• Conditional styling: Combine with other selectors (like :focus or :invalid ) to build smarter UI rules.

For example, if you're building a CMS where some fields are locked after approval, using :read-only makes it easy to give visual feedback without extra classes.

Another trick: You can invert the logic and write something like:

 input:not(:read-only) {
  /* Styles for editable inputs only */
}

That gives you more precision control without writing extra markup.

Browser Support and Caveats

These pseudo-classes are well-supported in modern browsers including Chrome, Firefox, Safari, and Edge. However, older browsers like Internet Explorer (especially versions before IE12) may not support them fully.

Also, keep in mind:

• :read-only and :read-write don't change behavior, only appear.
• Always pair visual cues with actual attributes ( readonly , disabled , etc.) for accessibility and functionality.

So while they're not essential for every project, they're definitely worth having in your CSS toolkit when working with forms or editable content.

Basically that's it.