* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
#mainBodyBG {
    position: fixed;
    top: 0;
    z-index: -4;
    width: 100%;
    height: 100%;
    object-fit: cover;
    background-repeat: no-repeat;
    background-size:cover;
    filter: blur(1px);
}

#mainBodyBG::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(ellipse at center, transparent 0%, transparent 40%, rgba(0, 0, 0, 0.4) 80%, rgba(0, 0, 0, 0.7) 100%);
    pointer-events: none;
}

.shell {
    position: fixed;
    top: 0;
    z-index: -4;
    width: 100%;
    height: 100%;
    object-fit: cover;
}
.button {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 380px;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    bottom: -80%;
}

.prev,
.next {
    transition: transform 0.25s ease;
    z-index: 99999;
}

.prev i,
.next i {
    font-size: 90px;
    color: #fff;
    cursor: pointer;
    text-shadow: 0 0 10px #ffffff;
}
.preview{
    font: 800;
    font-size: 90px;
    color: white;
    cursor: pointer;
    text-shadow: 0 0 10px #ffffff;
}
.preview:hover{
    color: #9e9e9e;
    text-shadow: 0 0 10px #9e9e9e;
}

.shell_body {
    width: 100%;
    transform: scale(.8);
    padding: 20px 0 150px 0;
}

.shell_slider {
    position: relative;
    margin-top: 20%;
    transition: transform 1s ease-in-out;
    background: transparent;
}

.item {
    cursor: pointer;
    position: relative;
    float: left;
    margin: 0 20px;
    transform: translate(-30%);
}

.frame {
    position: relative;
    width: 160%;
    height: 90%;
    transition: transform 1s ease-in-out;
    transform-style: preserve-3d;
    
}

.frame:after {
    content: "";
    position: absolute;
    bottom: -16%;
    width: 100%;
    height: 60px;
    background: #ffffff1c;
    box-shadow: 0px 0px 15px 5px #ffffff1c;
    transform: rotateX(90deg) translate3d(0px, -20px, 0px);
}

.box {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: absolute;
    width: 100%;
    height: 100%;
    border: 4px solid #fff;
    perspective: 1000px;
    transform-style: preserve-3d;
}

.box h1,
.box span {
    color: #fff;
    transform: translateZ(20px);
}

.box h1 {
    text-shadow: 0 0 30px #1f05b4;
    font-size: 100px;
}

.box span {
    position: absolute;
    bottom: 20px;
    padding: 0 25px;
    text-shadow: 0 0 10px #1f05b4;
}
.previewOnlinePage{
    display: none;
}
.front,
.left,
.right {
    box-shadow: 0 0 50px #ffffff;
    background-size: cover;
}

.right,
.left {
    top: 0;
    width: 60px;
    backface-visibility: hidden;
}
.left {
    left: 0;
    border-left-width: 5px;
    transform: translate3d(1px, 0, -60px) rotateY(-90deg);
    transform-origin: 0%;
}
.right {
    right: 0;
    border-right-width: 5px;
    transform: translate3d(-1px, 0, -60px) rotateY(90deg);
    transform-origin: 100%;
}


/* ========== 移动端适配 ========== */
@media (max-width: 768px) {
    /* 背景居中 */
    #mainBodyBG {
        background-position: center center;
    }

    .shell_body {
        transform: none;
        padding: 0;
        padding-top: calc(25vh - 44px);
        width: 100%;
        height: calc(100vh - 88px);
        margin-top: 88px;
        overflow: hidden;
        box-sizing: border-box;
    }
    .shell_slider {
        margin-top: 0;
        position: relative;
    }

    /* 卡片项：margin须与JS的margin=20一致 */
    .item {
        margin: 0 20px;
        transform: translate(0);
    }
    .frame { width: 100%; }
    .frame:after { display: none; }

    /* 卡片内容 */
    .box { border-width: 2px; }
    .box h1 { font-size: 32px; }
    .box span {
        font-size: 11px;
        bottom: 8px;
        padding: 0 12px;
        text-align: center;
    }

    /* 隐藏3D侧面 */
    .box.left, .box.right { display: none; }

    /* 按钮控制区域 */
    .button {
        width: 80%;
        max-width: 300px;
        position: fixed;
        bottom: 20px;
        left: 50%;
        transform: translateX(-50%);
        z-index: 100;
        display: flex;
        justify-content: space-between;
        align-items: center;
        background: rgba(0, 0, 0, 0.5);
        padding: 10px 20px;
        border-radius: 30px;
    }
    .prev i, .next i { font-size: 40px; }
    .preview {
        font-size: 18px;
        padding: 8px 16px;
        background: rgba(255, 255, 255, 0.15);
        border-radius: 20px;
    }
}

@media (max-width: 480px) {
    .shell_body { height: calc(100vh - 78px); margin-top: 78px; padding-top: calc(25vh - 39px); }
    .button { width: 90%; padding: 8px 16px; }
    .prev i, .next i { font-size: 30px; }
    .preview { font-size: 16px; padding: 6px 12px; }
    .box h1 { font-size: 24px; }
    .box span { font-size: 10px; padding: 0 8px; }
}