note mature content on post list

_includes/post.html

@@ -2,6 +2,12 @@
     <div class="card-body">
         <span class="blog-meta text-muted">{{ include.post.tags | join: ", " }}<br>{{ include.post.date | date_to_string }}</span>
         <h4 class="card-title"><a class="title-button" href="{{ include.post.url }}">{{ include.post.title }}</a></h4>
-        <div class="card-text">{{ include.post.description }}</div>
+        <div class="card-text">
+            {{ include.post.description }}
+
+            {% if include.post.mature %}
+                <p style="margin-top: 0.5rem; margin-bottom: 0">⚠️ This post contains mature content.</p>
+            {% endif %}
+        </div>
     </div>
 </div>