Split Widgets Using CSS Grid in Genesis https://wpsites.net/web-design/split-widgets-50-width-each/

functions.php

genesis_register_sidebar( array(
	'id'          => 'left',
	'name'        => __( 'Left' ),
) );

genesis_register_sidebar( array(
	'id'          => 'right',
	'name'        => __( 'Right' ),
) );

add_action( 'genesis_after_header', 'inline_widgets' );

function inline_widgets() {

if ( is_active_sidebar( 'left' ) || is_active_sidebar( 'right' ) ) {	

    echo '<div class="grid-wrapper">';

	genesis_widget_area( 'left', array(
		'before' => '<div class="left widget-area">',
		'after'  => '</div>',
	) );
	
	genesis_widget_area( 'right', array(
		'before' => '<div class="right widget-area">',
		'after'  => '</div>',
	) );	
	
    }
    
    echo '</div>';

}

style.css

.left {
	grid-area: left;
}

.right {
	grid-area: right;
}

.grid-wrapper {
    padding-top: 40px;
    padding-left: 40px;
    padding-right: 40px;
    display: grid;
    grid-gap: 40px;
	grid-template-columns: 1fr 1fr;
	grid-template-areas: "left right";
}

@media only screen and (max-width: 1023px) {

    .grid-wrapper {
        display: grid;
        grid-gap: 0;
	grid-template-columns: 1fr;
	grid-template-areas: 
	    "left"
	    "right";
    }
    
}