Прозрачность для header

.site-header{ 
	color: var(--BgColor); 
	height: 140px; 
	width: 100%; 
	background-color: var(--GeneralColor); 
	opacity: 0.25; 
}

<header class="site-header"> 
		<div class="head-wrap fw-row-container"> 
			<div class="site-branding fw-col-lg-3 fw-col-md-3 fw-col-sm-4 "> 
				<?php the_custom_logo(); ?> 
					<h1 class="site-title"><a href="<?php echo esc_url( home_url( '/' ) ); ?>" rel="home"><?php bloginfo( 'name' ); ?></a></h1> 
				<?php 
				 
				$description = get_bloginfo( 'description', 'display' ); 
				if ( $description || is_customize_preview() ) : ?> 
					<p class="site-description"><?php echo $description; /* WPCS: xss ok. */ ?></p> 
				<?php 
				endif; ?> 
			</div><!-- .site-branding --> 
			<nav class="main-navigation fw-col-lg-8 fw-col-lg-offset-1 fw-col-md-9 fw-col-sm-8 "> 
				<i id="menu-btn" class="fa fa-bars" aria-hidden="true"></i> 
				<?php 
					wp_nav_menu( array( 
						'theme_location' => 'menu-1', 
						'menu_id'        => 'primary-menu', 
					) ); 
				?> 
			</nav><!-- #site-navigation --> 
		</div><!-- #masthead --> 
	</header>