Centre align new menu area

I’m working on a site using LocalWP (offline) and have created a new menu area in Twenty Sixteen child theme. Menu functioning no problems. I’ve used CSS to customise it as needed but the only thing I cannot get to work is to centre the menu underneath the header image.

CODE in HEADER.PHP:
<nav id=”shop-navigation” class=”shop-nav” role=”navigation” aria-label=”<?php
esc_attr_e(‘Primary Menu’, ‘twentysixteen’);
?>”>
<?php
wp_nav_menu(array(
‘theme_location’ => ‘shop-menu’,
‘menu_class’ => ‘primary-menu’
));
?></nav>

CUSTOM CSS:

.shop-nav {
font-family: Montserrat, “Helvetica Neue”, sans-serif;
}

.shop-nav ul {
list-style: none;
}

.shop-nav a {
color: #1a1a1a;
display: block;
padding: 1em 1em;
}

.shop-nav a:hover,
.shop-nav a:focus {
color: #007acc;
}

.shop-nav .primary-menu > li {
float: left;
}

Can anyone point me in the right direction?