一、在模板下的thread.htm内查找

<span class="username">
 <a href="<?php echo url("user-$thread [uid]");?>" class="text-muted font-weight-bold"><?php echo $thread ['username'];?></a>
 </span>

在后面添加

<?php if ($thread ['user'] ['gid'] < 6 && $thread ['user'] ['gid'] > 0){?>
 <span class="badge badge-sm badge-danger"><?php echo $thread ['user'] ['groupname'];?></span>
 <?php }elseif($thread ['user'] ['gid'] > 100){?>
 <span class="badge badge-sm badge-info"><?php echo $thread ['user'] ['groupname'];?></span>
 <?php }else{?>
 <span class="badge badge-sm badge-secondary"><?php echo $thread ['user'] ['groupname'];?></span>
 <?php }?>

二、在模板文件post_list.inc.htm中查找

<!--{hook post_list_inc_username_after.htm}-->

在前面添加

<?php if ($_post ['user'] ['gid'] < 6 && $_post ['user'] ['gid'] > 0){?>
 <span class="badge badge-sm badge-danger"><?php echo $_post ['user'] ['groupname'];?></span> 
 <?php }elseif($_post ['user'] ['gid'] > 100){?> 
 <span class="badge badge-sm badge-success"><?php echo $_post ['user'] ['groupname'];?></span>
 <?php }else{?>
 <span class="badge badge-sm badge-secondary"><?php echo $_post ['user'] ['groupname'];?></span>
 <?php }?>

这是本站在用的，用户组用不同颜色显示，管理组红色背景，普通会员绿色背景，其它会员（被屏蔽，待验证等）用灰色背景。如果要修改样式，请修改 class="badge badge-sm badge-danger" 中的CSS样式，可以自定义CSS，也可以用默认的bootstrap。bootstrap的badge样式： https://v4.bootcss.com/docs/components/badge/