body {
    font-family: "Open Sans", "Helvetica Neue", Helvetica, "Arial", "游ゴシック", YuGothic, "ヒラギノ角ゴ ProN W3", "Hiragino Kaku Gothic ProN", "メイリオ", Meiryo, sans-serif;
    font-size: 13px;
}

.btn {
    font-size: 11px;
}

.error {
    color: red;
}