header {
    margin-bottom: 16px;
    padding: 8px 16px;
    background-color: rgb(190, 190, 190);
    color: white;
    text-align: center;
}

main {
    display: flex;
    justify-content: center;
}

.TRV_form {
    margin-bottom: 35px;
    padding: 10px 30px;
}

td {
    padding: 8px;
}

.box {
    box-sizing: border-box;
    width: 150px;
    height: 40px;
    margin: 0;
    padding: 0 10px;
}

.res_area {
    font-size: .8rem;
    letter-spacing: 1px;
    box-sizing: border-box;
    width: 300px;
    height: 200px;
    padding: 10px;
    line-height: 1.5;
    border-radius: 5px;
    border: 1px solid rgb(175, 175, 175);
}

.calc_button {
    width: 80px;
    height: 30px;
    border: 1px solid rgb(100, 100, 100);
    cursor: pointer;
    padding: 8px;
    font-weight: bold;
}