.btn {
    /* change bg color to get different hues    */
    color: white;
    border: none;
    border-radius: 5px;
    letter-spacing: 2px;
    text-align: center;
    vertical-align: middle;
    cursor: pointer;
    font-weight: bold;
    height: 1.6rem;
    line-height: 180%;
    padding: 0 1.2rem;
}

.btn_small {
    font-size: 1rem;
}

.btn_middle {

}

.btn_big {

}

.mt-6 { margin-top: 6px; }
.mt-8 { margin-top: 8px; }
.mt-10 { margin-top: 10px; }
.mt-12 { margin-top: 12px; }
.mt-14 { margin-top: 14px; }
.mt-16 { margin-top: 16px; }

.ml-6 { margin-left: 6px; }
.ml-8 { margin-left: 8px; }
.ml-10 { margin-left: 10px; }
.ml-12 { margin-left: 12px; }
.ml-14 { margin-left: 14px; }
.ml-16 { margin-left: 16px; }

.btn_bg_salmon {
    background-color: salmon;
}

@media screen and (max-width: 736px) {
    .btn {
        height: 1.4rem;
        line-height: 150%;
        padding: 0 0.8rem;
    }
    .btn_small {
        font-size: 0.8rem;
    }
}