Setting a viewport height without stretching a featured image. #wordpress

singular.php

<?php if ( has_post_thumbnail() && ! post_password_required() ) : ?>

	<div class="featured-image" style='background-image: url(" <?= get_the_post_thumbnail_url(get_the_ID(), 'full'); ?>");'></div>

<?php endif; ?>

styles.css

.featured-image img {
	width: 100%;
}

.featured-image {
	position: relative;
    min-height: 30rem;
    height: 75vh;
    max-width: 1600px;
    margin-left: auto;
    margin-right: auto;
    margin-top: 1em;
    background-position: center center;
    background-repeat: no-repeat;
    background-size: cover;
}