Set width of text input form with blueprint

I try to layout a form composed by a label and a text input. I want to set the width of the in开发者_开发问答put element because the default is too wide.

<div class="container">
    <div class="span-24 last">
        <label for="age">Age: </label>
        <input class="text span-2"/>
    </div>
</div>

I tried to use span-2 but the input text is displayed before the label.

input
{
    width: 300px;
}

will set the input width to 300px.