.btt{right:var(--btt-right,18px);bottom:calc(var(--btt-bottom,22px) + env(safe-area-inset-bottom));z-index:var(--btt-z,45);width:var(--btt-size,46px);height:var(--btt-size,46px);border:var(--btt-border,1px solid #00000014);border-radius:var(--btt-radius,999px);background:var(--btt-bg,#fff);color:var(--btt-fg,#1a1a1a);box-shadow:var(--btt-shadow,0 6px 18px #00000024);clip-path:var(--btt-clip,none);-webkit-backdrop-filter:var(--btt-backdrop,none);backdrop-filter:var(--btt-backdrop,none);cursor:pointer;opacity:0;visibility:hidden;-webkit-tap-highlight-color:transparent;place-items:center;padding:0;transition:opacity .22s,transform .26s,visibility 0s linear .26s,background-color .18s,color .18s;display:grid;position:fixed;transform:translateY(14px)scale(.92)}.btt[data-shown="1"]{opacity:1;visibility:visible;transition-delay:0s;transform:none}.btt:hover{background:var(--btt-hover-bg,var(--btt-bg,#fff));color:var(--btt-hover-fg,var(--btt-fg,#1a1a1a))}.btt:hover svg{transform:translateY(-2px)}.btt:active{transform:var(--btt-press,translateY(2px))}.btt svg{transition:transform .18s}.btt svg path{stroke-width:var(--btt-stroke,2.4);stroke-linecap:var(--btt-cap,round);stroke-linejoin:var(--btt-cap-join,round)}.btt:focus-visible{outline:3px solid var(--btt-focus,currentColor);outline-offset:3px}@media (prefers-reduced-motion:reduce){.btt,.btt svg{transition:none}}:root{--btt-bg:var(--surface-raised);--btt-fg:var(--text);--btt-border:1px solid var(--border);--btt-hover-bg:var(--action);--btt-hover-fg:var(--on-action);--btt-shadow:0 10px 26px #00000059;--btt-focus:var(--focus,var(--action));--btt-backdrop:blur(10px)}:root:not([data-brand-theme]),:root[data-brand-theme=classic]{--btt-bg:linear-gradient(135deg, var(--action-start), var(--action-end));--btt-fg:#fff;--btt-border:0;--btt-hover-fg:#fff;--btt-shadow:0 10px 28px #6c5ce773}:root:not([data-brand-theme]) .btt:hover,:root[data-brand-theme=classic] .btt:hover{filter:brightness(1.12)}:root[data-brand-theme=netflix]{--btt-radius:6px;--btt-fg:#e50914;--btt-shadow:0 10px 26px #0009}:root[data-brand-theme=youtube]{--btt-bg:#fff;--btt-fg:#0f0f0f;--btt-border:1px solid #e5e5e5;--btt-hover-bg:#f2f2f2;--btt-hover-fg:#0f0f0f;--btt-shadow:0 4px 14px #0000001f}:root[data-brand-theme=bilibili]{--btt-bg:#fff;--btt-fg:var(--action);--btt-border:1px solid var(--border);--btt-shadow:0 6px 18px #d6246e2e}:root[data-brand-theme=iqiyi]{--btt-bg:#fff;--btt-fg:var(--action);--btt-border:1px solid var(--border);--btt-radius:12px;--btt-shadow:0 6px 18px #00850a29}@media (max-width:1023.98px){:root{--btt-bottom:92px;--btt-right:14px;--btt-size:42px}}