the_posts_pagination( array( 'mid_size' => 2,<br ?--> 'prev_text' => __( 'Back', 'textdomain' ),
'next_text' => __( 'Onward', 'textdomain' ),
) );

.page-numbers {
display: inline-block;
padding: 5px 10px;
margin: 0 2px 0 0;
border: 1px solid #eee;
line-height: 1;
text-decoration: none;
border-radius: 2px;
font-weight: 600;
}
.page-numbers.current,
a.page-numbers:hover {
background: #f9f9f9;
}