/* 回到顶部 */
#back-to-top {          
    position:fixed;
    right:28px;
    bottom:28px;
    z-index:9;
    display:flex;
    align-items:center;
    justify-content:center;
    width:48px;
    height:48px;
    border-radius:999px;
    color:#fff !important;
    background:#e65475;
    box-shadow:0 12px 28px rgba(44,36,39,0.18);
    font-size:12px;
    font-weight:900;
    line-height:1.1;
    text-align:center;
    opacity:0;
    pointer-events:none;
    transform:translateY(14px);
    transition:opacity 0.2s ease, transform 0.2s ease;  
    cursor:pointer;     
}

#back-to-top.is-visible {
    opacity:1;
    pointer-events:auto;
    transform:translateY(0);
}