Electro v2 - Change handheld screen size

functions.php

if ( ! function_exists( 'electro_mobile_header_v1' ) ) {
    /**
     * Displays Mobile Header v1
     */
    function electro_mobile_header_v1() {
        if( has_electro_mobile_header() ) : ?>
            <div class="container hidden-lg-up">
                <div class="mobile-header-v1 handheld-stick-this">
                    <?php
                    /**
                     * @hooked electro_off_canvas_nav - 10
                     * @hooked electro_header_logo - 20
                     * @hooked electro_handheld_header_links - 30
                     */
                    do_action( 'electro_mobile_header_v1' ); ?>
                </div>
            </div>
        <?php endif;
    }
}