Enlarge button size so it is more table-friendly.

app/templates/userpage_post.html

@@ -25,7 +25,7 @@
     <input type="button" id="btn-selection" value="全部勾选" onclick="toggleCheckboxSelection(true)" />
   </p>
       <form method="post" action="/{{username}}/mark">
-       <button type="submit" name="add-btn" class="btn btn-primary btn-lg">加入我的生词簿</button>
+       <button type="submit" name="add-btn" class="btn btn-outline-primary btn-lg">加入我的生词簿</button>
        {% for x in lst %}
           {% set word = x[0]%}
         <p>