maple-bbs/maple/templates/auth/validate.html

<a id="clickCode" href="javascript:void(0)" >
    <img id="changeCode" src="{{ url_for('auth.validcode') }}" style="width:120px;height:30px;" alt="验证码">
</a>
<span>{{ form.code(class="form-control input-sm",style="width:120px;display: inline;") }}</span>