/Application/Forum/View/default/Public/_nav.html  中

<a type="submit" class="input-btn"><i class="icon-search"></i> </a>

修改为

 <button type="submit" class="input-btn" style="border-color: transparent;background: transparent;padding: 0 10px 0 10px;"><i class="icon-search"></i></button>

_nav.rar