<!-- Portfolio Grid Section -->
    <section id="portfolio" class="bg-light-gray">
        <div class="container">
            <div class="row">
                <div class="col-lg-12 text-center">
                    <h2 class="section-heading">Projects</h2>
                    <h3 class="section-subheading text-muted">
                      Completed Projects funded by the Open Annotation Fund.
                    </h3>
                </div>
            </div>
            <div class="row">
            {% for post in site.posts %}
                <div class="col-md-4 col-sm-6 portfolio-item">
                    <a href="#portfolioModal{{ post.modal-id }}" class="portfolio-link" data-toggle="modal">
                        <div class="portfolio-hover">
                            <div class="portfolio-hover-content">
                                <i class="fa fa-plus fa-3x"></i>
                            </div>
                        </div>
                        <img src="img/portfolio/{{ post.thumbnail }}" class="img-responsive" alt="">
                    </a>
                    <div class="portfolio-caption">
                      <h4><a href="#portfolioModal{{ post.modal-id }}" class="portfolio-link" data-toggle="modal">{{ post.title }}</a></h4>
                        <p class="text-muted">{{ post.subtitle }}</p>
                        <hr />
                        <p class="text-left">{{ post.description }}</p>
                    </div>
                </div>
            {% endfor %}
            </div>
        </div>
    </section>

<!-- Portfolio Grid Section -->
    <section id="portfolio" class="bg-light-gray">
        <div class="container">
            <div class="row">
                <div class="col-lg-12 text-center">
                    <h2 class="section-heading">Projects</h2>
                    <h3 class="section-subheading text-muted">
                      Completed Projects funded by the Open Annotation Fund.
                    </h3>
                </div>
            </div>
            <div class="row">
            {% for post in site.posts %}
                <div class="col-md-4 col-sm-6 portfolio-item">
                    {% if post.thumbnail %}
                    <a href="#portfolioModal{{ post.modal-id }}" class="portfolio-link" data-toggle="modal">
                        <div class="portfolio-hover">
                            <div class="portfolio-hover-content">
                                <i class="fa fa-plus fa-3x"></i>
                            </div>
                        </div>
                        <img src="img/portfolio/{{ post.thumbnail }}" class="img-responsive" alt="">
                    </a>
                    {% endif %}
                    <div class="portfolio-caption">
                      <h4><a href="#portfolioModal{{ post.modal-id }}" class="portfolio-link" data-toggle="modal">{{ post.title }}</a></h4>
                        <p class="text-muted">{{ post.subtitle }}</p>
                        <hr />
                        <p class="text-left">{{ post.description }}</p>
                    </div>
                </div>
            {% endfor %}
            </div>
        </div>
    </section>

Hide thumbnail if not set
Hide thumbnail if not set
