* {
    padding: 0;
    margin: 0;
}

body {
    font-family: "微軟正黑體",Arial, Helvetica, sans-serif;
    align-items: center;
    flex-direction: column;
    display: flex;
    background-image: linear-gradient(to top, #fddb92 0%, #d1fdff 100%);
    background-attachment: fixed;
    background-repeat: no-repeat;
    height: 100%;
    width: 100%;
}



h1 {
    color: #009688;
    padding: 1em 0;
    font-family: monospace;
    text-align: center;
}



.container {
    width: 640px;
    margin: 0 auto;
}

    .container .block ul {
        display: inline-block
    }


.card-wrapper {
    list-style: none;
    margin: 16px;
}

.card {
    position: relative;
    transform-style: preserve-3d;
    float: left;
    margin: 5px 25px 5px 25px;
    width: 100px;
    height: 140px;
}

    .card.active {
        transform: rotateY(180deg);
        -webkit-transform: rotateY(180deg);
    }

    .card img {
        width: 100%;
        position: absolute;
        left: 0;
        top: 0;
        display: block;
        -webkit-backface-visibility: hidden;
        backface-visibility: hidden;
        border-radius: 10px;
        overflow: hidden;
    }

/* 翻轉效果 */
.front {
    transform: rotateY(180deg);
    -webkit-transform: rotateY(180deg);
}


.transition {
    transition: all .5s;
    -webkit-transition: all .5s;
}

.score {
    color: #ff0000;
    font-weight: bold;
    font-size: 20px;
}

#tiktok {
    width: 400px;
    height: 15px;
    background: red;
    border: 2px solid #4CAF50;
    margin: 10px auto;
    border-radius: 3px;
}

#counter {
    width: 100%;
    height: 100%;
    background: white;
    float: right;
}

.mask {
    width: 640px;
    height: inherit;
    position: absolute;
    top: 0;
    z-index: 99;
    background: rgba(0,0,0,0.5);
}

.intro {
    width: 400px;
    height: 400px;
    background: #F8F8C6;
    margin: 100px auto 0px auto;
    font-weight: bolder;
    font-size: 18px;
    line-height: 30px;
    padding: 20px;
}

    .intro button {
        display: block;
        padding: 15px 20px;
        font-size: 20px;
        cursor: pointer;
        color: #fff;
        background-color: #4CAF50;
        border: none;
        border-radius: 15px;
        box-shadow: 0 9px #999;
        margin: 60px auto 0 auto;
    }

        .intro button:hover {
            background-color: #3e8e41
        }

        .intro button:active {
            background-color: #3e8e41;
            box-shadow: 0 5px #666;
            transform: translateY(4px);
        }

.chk {
    margin-left: 80px;
}

#timer {
    height: 25px;
    display: block;
}

footer {
    background-color: black;
    color: white;
    text-align: center;
    padding: 5px 0;
    width: 100%;
    position: absolute;
    bottom: 0;
}
footer a {
    color: white;
}