html – 引导3：如何在单行和其他输入上单独输入两个表单输入？

有谁知道该怎么办？

这是Fiddle

<style>
.reg_name {
 max-width:200px;
}
</style>


<form name="registration_form" id='registration_form' class="form-inline">

        <div class="form-group">
            <label for="firstname" class="sr-only"></label>
            <input id="firstname" class="form-control input-group-lg reg_name" type="text" name="firstname"
                   title="Enter first name"
                   placeholder="First name"/>
        </div>

        <div class="form-group">
            <label for="lastname" class="sr-only"></label>
            <input id="lastname" class="form-control input-group-lg reg_name" type="text" name="lastname"
                   title="Enter last name"
                   placeholder="Last name"/>
        </div>

    <div class="form-group">
        <label for="username" class="sr-only"></label>
        <input id="username" class="form-control input-group-lg" type="text" autocapitalize='off' name="username"
               title="Enter username"
               placeholder="Username"/>
    </div>

    <div class="form-group">
        <label for="password" class="sr-only"></label>
        <input id="password" class="form-control input-group-lg" type="password" name="password"
               title="Enter password"
               placeholder="Password"/>
    </div>

 </form>