.fbs-btn{position:fixed;z-index:9999;display:flex;align-items:center;justify-content:center;border-radius:50%;background:#fff;box-shadow:0 2px 10px rgba(0,0,0,.3);transition:transform .2s ease}
.fbs-btn:hover{filter:brightness(1.05)}
.fbs-btn img{width:100%;height:100%;object-fit:contain;border-radius:50%;display:block}
.fbs-tip{position:absolute;top:50%;transform:translateY(-50%);white-space:nowrap;background:#222;color:#fff;font-size:13px;line-height:1;padding:8px 10px;border-radius:4px;opacity:0;visibility:hidden;pointer-events:none;transition:opacity .2s}
.fbs-btn:hover .fbs-tip,.fbs-btn:focus .fbs-tip{opacity:1;visibility:visible}
@media print{.fbs-btn{display:none !important}}