Side meta box checkbox :checked state visually invisible in WordPress 7.0 Beta 5

[fernandot]

In WordPress 7.0 Beta 5, checkboxes inside side meta boxes are visually indistinguishable between checked and unchecked states. The checkbox does toggle correctly (.checked returns true), but the visual feedback is completely lost.

This affects native HTML checkboxes inside classic PHP meta boxes registered
via add_meta_box() with 'side' context. It does not affect Gutenberg's
own React-based sidebar controls (Categories, Tags, etc.) as those render
outside the .edit-post-meta-boxes-area container.

Root cause

A CSS rule in load-styles overrides the :checked state for checkboxes inside side meta boxes:

.edit-post-meta-boxes-area .metabox-location-side .postbox input[type=checkbox]:checked {
    background: #fff;
    border-color: #757575;
}

This rule has higher specificity than the default admin :checked styles (which use var(--wp-admin-theme-color) for background and border), making checked checkboxes look identical to unchecked ones — white background with gray border in both states.

Steps to reproduce

1. Register a simple meta box with context 'side' containing a native <input type="checkbox">:

add_meta_box(
    'my_test_metabox',
    'Test Checkbox',
    'my_test_metabox_callback',
    'post',
    'side',
    'default'
);

function my_test_metabox_callback( $post ) {
    echo '<label>';
    echo '<input type="checkbox" name="test_check" value="1">';
    echo ' Enable something';
    echo '</label>';
}

2. Open the post editor (block editor).
3. Click the checkbox inside the side meta box.
4. Observe: no visual change. The checkbox appears unchecked.
5. Run in browser console: document.querySelector('#my_test_metabox input[type="checkbox"]').checked — returns true.

Expected behavior

The checkbox should display the standard WordPress admin checked state (colored background with white checkmark SVG).

Actual behavior

The checkbox remains visually white/unchecked regardless of its actual state.

Environment

• WordPress 7.0 Beta 5
• Tested with Twenty Twenty-Five theme, all plugins deactivated except a minimal test plugin with the above code
• Tested in Chrome and Firefox
• No console errors

Suggested fix

Remove or correct the :checked override in the side meta box styles so it does not reset background and border-color to values identical to the unchecked state. The rule should either be removed entirely or updated to preserve the default admin :checked styling:

.edit-post-meta-boxes-area .metabox-location-side .postbox input[type=checkbox]:checked {
    background: var(--wp-admin-theme-color, #2271b1);
    border-color: var(--wp-admin-theme-color, #2271b1);
}

[fernandot]

checkbox checked but not showed that is checked

[wildworks]

Thanks for the report. I'll close this ticket in favor of ​https://github.com/WordPress/gutenberg/issues/76717.

This problem should be fixed on the Gutenberg side.

[fernandot]

Thanks, and apologies, I've noticed that is better to post it in Github after submitting this ticket :)

Replying to wildworks:

Thanks for the report. I'll close this ticket in favor of ​https://github.com/WordPress/gutenberg/issues/76717.

This problem should be fixed on the Gutenberg side.