<?php
            $previouspost = get_previous_post($in_same_cat, $excluded_categories);
            if ($previouspost != null) {
            
            echo '<div class="side-post"><div class="upper"><div class="fade"></div><h3>';
            previous_post_link('%link');
            echo '</h3>';
            previous_post_excerpt();
            echo '</div><span class="btn-readon">';
            previous_post_link('%link');
            echo '</span><span class="sub-txt">Previous Entry</span></div>';
        } ?>

            <?php
            $nextpost = get_next_post($in_same_cat, $excluded_categories);
            if ($nextpost != null) {
            
            echo '<div class="side-post"><div class="upper"><div class="fade"></div><h3>';
            next_post_link('%link');
            echo '</h3>';
            next_post_excerpt();
            echo '</div><span class="btn-readon">';
            next_post_link('%link');
            echo '</span><span class="sub-txt">Next Entry</span></div>';
        } ?>

    
        <div class="side-post"><div class="upper"><div class="fade"></div><h3>Навигация по сайту</h3>
text</div><span class="btn-readon"></span><span class="sub-txt"></span></div>