<style type="text/css">
    .btn {
        display: block;
        background: none rgb(40, 60, 220);
        color: rgb(255, 255, 255);
        display: block;
        font-size: 15px;
        width: 300px;
        height: 300px;
    }
</style>
<input class="btn" type="submit" value="Should be located in the center" />