::-webkit-scrollbar-track-piece{width:10px;background-color:#f2f2f2}
::-webkit-scrollbar{width:8px;height:6px}
::-webkit-scrollbar-thumb{height:50px;background-color:rgba(0,0,0,.3); border-radius: 1000px;}
::-webkit-scrollbar-thumb:hover{background:#333}

/* Firefox：与官网灰系滚动条观感一致 */
html {
    scrollbar-width: thin;
    scrollbar-color: rgba(0, 0, 0, 0.35) #f2f2f2;
}

/* 全局返回顶部（页脚片段 #back-to-top） */
.back-to-top {
    position: fixed;
    bottom: 1.5rem;
    right: 1.5rem;
    width: 48px;
    height: 48px;
    padding: 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    z-index: 1040;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: opacity 0.25s ease, visibility 0.25s ease, transform 0.25s ease, box-shadow 0.2s ease;
    box-shadow: 0 4px 14px var(--shadow-color, rgba(15, 23, 42, 0.12));
    display: flex;
    align-items: center;
    justify-content: center;
}
.back-to-top i {
    font-size: 1.5rem;
    line-height: 1;
}
.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}
.back-to-top:hover {
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--shadow-color, rgba(15, 23, 42, 0.18));
}
.back-to-top.visible:hover {
    transform: translateY(-2px);
}
.back-to-top:focus-visible {
    outline: 3px solid rgba(30, 111, 217, 0.45);
    outline-offset: 2px;
}
@media (max-width: 576px) {
    .back-to-top {
        bottom: 1rem;
        right: 1rem;
        width: 44px;
        height: 44px;
    }
    .back-to-top i {
        font-size: 1.35rem;
    }
}

/* 赞/踩：Boxicons 手势 EA9B（.bx-like）；踩为同形上下镜像（scaleY，见 item_detail / browse 卡片） */
.bx-hand-dislike-flip {
    transform: scaleY(-1);
}