Example error template that can be used in Custom System Messages, an ExpressionEngine add-on.

error.html

{if csm:error == TRUE AND csm:action == 11}
    <div class="error-message">
        <strong>The following errors were encountered:</strong> 
        <ul class="error-fields">
            {csm:content}
        </ul>
    </div>
{/if}
<div class="grid-row">
    <h3>SIGN IN</h3>
    <p>Don’t have an account yet? <a href="{path='account/register'}">Create an account.</a></p>
    <p><a href="{path='account/forgot-password'}">Forgot your password?</a></p>
</div>
<div class="grid-row"> 
    {exp:member:login_form return="site/index" form_class="lj-form clearfix"}
        <div class="grid-col size3of6">
            <label for="signin-email">Email Addresss <span>(Username)</span><span class="input-required"> *</span></label>
            <input type="text" id="signin-email" name="username" />
        </div>        
        <div class="grid-col size3of6">
            <label for="signin-password">PASSWORD<span class="input-required"> *</span></label>
            <input type="password" id="signin-password" name="password" />
            <button type="submit" name="submit" value="SIGN IN">SIGN IN</button>
        </div>        
    {/exp:member:login_form}
</div>