Button: Default

<div class="b">
    <div class="m-v400 m-h200">
        <button class="btn">Next</button>
    </div>
    <div class="m-v400 m-h200">
        <button class="btn" disabled>Next</button>
    </div>
    <div class="m-v400 m-h200">
        <a class="btn">Next</a>
    </div>
    <div class="m-v400 m-h200">
        <a class="btn btn--sm btn--100">Next</a>
    </div>
</div>