themes-wordpress/heiwa/assets/theme.css

/**
 * We need this until https://github.com/WordPress/gutenberg/issues/44182 gets resolved
 */
.wp-block-navigation__responsive-close {
	max-width: none;
}

/**
 * Override the default padding value from Gutenberg to avoid the icon jumping
 */
.wp-block-navigation__responsive-container.is-menu-open {
	padding-top: var(--wp--custom--gap--vertical);
}