fixed media card min-width, and centering on superevent log entries

gracedb/events/templatetags/mediaviews.py

@@ -83,7 +83,7 @@ img_style_template = """max-height= 250px;
 """
 
 image_card_div = """
-<div class="card my-3 log-comment-card">
+<div class="card my-3 log-comment-card" style="min-width:250px;">
   <div class="card-header log-comment-card-header text-left">
     <h7>Log Image</h7>
   </div>

gracedb/templates/superevents/log_entry_details.html

@@ -21,7 +21,7 @@
 
        <p><center>
        Use buttons to expand/collapse log sections.</p>
-       <p><center>
+       <p>
        {{ log_list|logboxes }}
        </center></p>