wordpress主题中<em>的未知输出

on my new theme in wordpress a <em> Tag is outputed, but i don't know why... I dont use any <em> Tags anywhere in my theme, so i can't understand why this is outputed and destroys my design.

Here the Content of my index.php

 <?php get_header(); ?>
<div class="row">
    <div class="col-sm-12 blog-content">
        <div class="container">
            <div class="col-sm-8 blog-main">
                <?php if (have_posts()) : while (have_posts()) : the_post(); ?>
                    <div class="col-sm-12 blog-post">
                         <div class="date">
                            <div class="corner"></div>
                            <?php the_date('d M Y'); ?>
                        </div>
                        <h2><a href="<?php the_permalink() ?>"><?php the_title(); ?></a></h2>
                        <div class="meta">
                            <i class="icon-user"></i>
                            <span><?php the_author(); ?></span>

                            <i class="icon-bookmark"></i>
                            <span><?php the_category(', '); ?></span>

                            <i class="icon-bubble"></i>
                            <a href="<?php the_permalink() ?>"><?php comments_number('0 Kommentare', '1 Kommentare', '(% Kommentare)' );?></a>
                        </div>
                        <div class="entry">
                            <?php echo apply_filters('the_content', substr(get_the_content(), 0, 400) ); ?>
                        </div>
                        <div class="row">
                            <div class="col-sm-offset-8 col-sm-4 col-md-offset-9 col-md-3 col-lg-offset-9 col-lg-3 more">
                                <div class="btn">
                                    <a href="<?php the_permalink() ?>">Mehr lesen</a>
                                </div>
                            </div>
                        </div>
                    </div>
                <?php endwhile; endif; ?>
            </div>

            <div class="col-sm-3 col-sm-offset-1 blog-sidebar">
                <?php get_sidebar(); ?>
            </div>
        </div>
    </div>
</div>

<?php get_footer(); ?>

Here you can watch my problem live. thorstenreichelt.de

Thanks for Help ;)

There is a em tag in your content (not in your theme). As you truncate it for the preview, in the first 400 characters you have the opening em tag but not the closing one, so the final HTML and your design are "broken".

Have a look at strip_tags() PHP function, or any equivalent used in Wordpress theming functions.

Could it be that you're pasting in some content to that post from somewhere, and its some formatting thats coming across with it.

Have you gone into edit that post and click "text" in the top right corner of the main editing area, next to where it says visual. Is there a stray tag there?

Try add this:

remove_filter ('the_content',  'wpautop');
remove_filter ('comment_text', 'wpautop');

at the final of the functions.php file from your theme.