wp-includes/block-supports/layout.php:22Returns layout definitions, keyed by layout type.
array[]function wp_get_layout_definitions() { $layout_definitions = array( 'default' => array( 'name' => 'default', 'slug' => 'flow', 'className' => 'is-layout-flow', 'baseStyles' => array( array( 'selector' => ' > .alignleft', 'rules' => array( 'float' => 'left', 'margin-inline-start' => '0', 'margin-inline-end' => '2em', ), ), array( 'selector' => ' > .alignright', 'rules' => array( 'float' => 'right', 'margin-inline-start' => '2em', 'margin-inline-end' => '0', ), ), array( 'selector' => ' > .aligncenter', 'rules' => array( 'margin-left' => 'auto !important', 'margin-right' => 'auto !important', ), ), ), 'spacingStyles' => array( array( 'selector' => ' > :first-child', 'rules' => array( 'margin-block-start' => '0', ), ), array( 'selector' => ' > :last-child', 'rules' => array( 'margin-block-end' => '0', ), ), array( 'selector' => ' > *', 'rules' => array( 'margin-block-start' => null, 'margin-block-end' => '0', ), ), ), ), 'constrained' => array( 'name' => 'constrained', 'slug' => 'constrained', 'className' => 'is-layout-constrained', 'baseStyles' => array( array( 'selector' => ' > .alignleft', 'rules' => array( 'float' => 'left', 'margin-inline-start' => '0', 'margin-inline-end' => '2em', ), ), array( 'selector' => ' > .alignright', 'rules' => array( 'float' => 'right', 'margin-inline-start' => '2em', 'margin-inline-end' => '0', ), ), array( 'selector' => ' > .aligncenter', 'rules' => array( 'margin-left' => 'auto !important', 'margin-right' => 'auto !important', ),Introduced in 6.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/block-supports/layout.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.