.back_cover {

    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    z-index: 1000;
    padding: 20px;
    box-sizing: border-box;
    background-color: #000;
    background-color: rgba(0, 0, 0, 0.9);
    text-align: center;

}

.show {
    visibility: visible;
}

.hide {
    visibility: hidden;
}

.modal {
    display: inline-block;
    vertical-align: middle;
    position: relative;
    z-index: 2;
    max-width: 500px;
    box-sizing: border-box;
    width: 90%;
    background: #fff;
    padding: 15px 30px;
    text-align: left;
}

.back_cover:before {
    content: "";
    display: inline-block;
    height: 100%;
    vertical-align: middle;
    margin-right: -0.05em;
}

.back_cover a.button, button.button, input.this_submit {
    width: 100%;
    margin-bottom: 10px;
    display: inline-block;

    height: 37px;
    line-height: 37px;
    letter-spacing: 0.1px;
    text-align: center;
    color: #ffffff;
    text-decoration: none;
    font-size: 15px;
    background-color: #000000;
    font-family: "Helvetica Neue", Helvetica, Arial, "微軟正黑體", sans-serif;
    border: 0;
    -webkit-transition: all 150ms ease-out;
    -moz-transition: all 150ms ease-out;
    -o-transition: all 150ms ease-out;
    -ms-transition: all 150ms ease-out;
    transition: all 150ms ease-out;
}

.back_cover .a4 {

    font-size: 0.8em;
    margin: 10px 0;
}

.back_cover img {
    width: 100%;
}

.back_cover a.close-modal {
    position: absolute;
    top: 10px;
    right: 10px;
    display: block;
    width: 30px;
    height: 30px;
    text-indent: -9999px;
    background-image: url(/assets/imgs/x.png);
    background-repeat: no-repeat;
    cursor: pointer;
}