Header higher than menu

hi, you can create a child theme (see here https://codex.ww.wp.xz.cn/Child_Themes ), copy header.php file and change the code in the it to this one

<!-- Header -->

		<div class="sg-header-area">
			<div class="header-wrap">

			<?php
				do_action( 'sgwindow_header_image' );
			?>

			</div><!-- .header-wrap -->
		</div><!-- .sg-header-area -->

		<header id="masthead" class="site-header" role="banner">	

			<?php do_action( 'sgwindow_header_top' ); ?>

		</header><!-- #masthead -->

		<!-- Header -->

		<div class="sg-header-area">
			<div class="header-wrap">

			<?php
				get_sidebar( 'top' );
			?>

			</div><!-- .header-wrap -->
		</div><!-- .sg-header-area -->