php-ppub/themes/baseline/navigation.php

<?php

function baseline_navigation() {
    ?>
    <ul class="compressed">
        <li><a href="<?php echo(SITE_URL);?>/"><span class="icon">📰</span>Latest</a></li>
        <li><a href="<?php echo(SITE_URL);?>/feed.rss"><span class="icon">🛜</span>RSS Feed</a></li>
    </ul>
    <?php
}

function baseline_banner_css() {
    if(SITE_BANNER != null) { ?>
        header[role="banner"] {
            background:
                url("<?php echo(SITE_BANNER); ?>");
        }
        @media (prefers-color-scheme: dark) {
            header[role="banner"] {
                background:
                    linear-gradient(
                        rgba(43, 54, 65, 0.6),
                        rgba(43, 54, 65, 0.6)
                    ),
                    url("<?php echo(SITE_BANNER); ?>");
            }
        }
        <?php 
    }
}