:root {
    --maxWidth: 960px;
    --cardWidth: 200px;
    --cardHeight: 300px;
    --colorMain: #3498db;
    --colorMainDarker: #2980b9;
    --colorSecundary: #9b59b6;
    --colorSecundaryDarker: #9b59b6;
}

html, body {
    position: relative;
    height: 100%;
    margin: 0;
    padding: 0;
}
/* body {
    background-color: #eeeeee;
    font-family: 'helvetica', sans-serif;
    font-size: 16px;
    transform: translate3d(0,0,0);
    background: linear-gradient(135deg, var(--colorMainDarker) 0%, var(--colorSecundaryDarker) 100%);
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#1e5799', endColorstr='#7db9e8',GradientType=1 );
} */
.img{
    width: 200px; /* 设置logo的宽度 */
    height: auto; /* 高度自动调整以保持图片比例 */
    border-radius: 10px;
}

.containercard {
    position: relative;
    /* width: 100%; */
    /* max-width: var(--maxWidth); */
    /* min-height: 100%; */
    margin: 0px auto;
    padding: 20px;
    box-sizing: border-box;
    display: flex;
    flex-direction: row;
    /* flex-wrap: wrap; */
    justify-content: center;
    align-items: center;
    /* border-radius: 20px; */
}

.element-card {
    position: relative;
    width: var(--cardWidth);
    height: var(--cardHeight);
    transform-style: preserve-3d;
    border-radius: 10px;
    transform: rotatey(0deg) translatex(0px) translatey(0px);
    transition: all 0.6s cubic-bezier(0.680, -0.550, 0.265, 1.550);
    box-shadow: 4px 4px 20px rgba(0,0,0,0.4);
    margin: 5px;
    cursor: pointer;
}

.element-card:hover {
    transform: rotatey(45deg) translatex(0px) translatey(0px);
}

.element-card.open {
    width: calc(1.5 * var(--cardWidth));
    height: calc(1.5 * var(--cardHeight));
    transform: rotatey(-180deg) translatex(0px) translatey(0px);
}

.element-card .front-facing {
    transform: rotateY(0deg) translateZ(2px);
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background-color: #ecf0f1;
    border: 2px white solid;
    border-radius: 10px;
}

.element-card .front-facing .abr {
    width: 100%;
    position: absolute;
    top: 50%;
    left: 0;
    font-size: 42px;
    margin: -35px 0 0 0;
    text-align: center;
    color: var(--colorMain);
}

.element-card .front-facing .title {
    width: 100%;
    position: absolute;
    top: 50%;
    left: 0;
    text-transform: uppercase;
    font-size: 12px;
    margin: 15px 0 0 0;
    text-align: center;
    color: var(--colorMain);
}

.element-card .front-facing .atomic-number {
    position: absolute;
    top: 10px;
    left: 10px;
    font-size: 12px;
    color: var(--colorMainDarker);
}

.element-card .front-facing .atomic-mass {
    position: absolute;
    bottom: 10px;
    right: 10px;
    font-size: 12px;
    color: var(--colorMainDarker);
}

.element-card .back-facing {
    transform: rotateY(180deg) translateZ(0px);
    display: flex;
    flex-direction: column;
    flex-wrap: nowrap;
    justify-content: center;
    align-items: center;
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background-color: #ecf0f1;
    border: 2px white solid;
    border-radius: 10px;
    padding: 20px;
    /* text-align: center; */
    overflow: hidden;
}

.element-card .back-facing p {
    font-size: 14px;
    margin: 0;
}

.element-card .back-facing a.btn {
    display: inline-block;
    background-color: white;
    padding: 5px 15px;
    margin: 20px 0 0 0;
    color: #eee;
    background-color: var(--colorMain);
    text-decoration: none;
    border-radius: 3px;
}

.element-card .back-facing a.btn:hover,
.element-card .back-facing a.btn:focus {
    color: #fff;
    background-color: var(--colorMainDarker);
}