.chat-screen .chat-history{
 scroll-behavior:auto;overflow-anchor:none;overscroll-behavior-y:contain;
 -webkit-overflow-scrolling:touch;touch-action:auto;
 overflow-y:scroll;overflow-x:hidden;will-change:scroll-position;
}
/* A real 1px overflow enables Safari's own rubber band even in a short chat.
   Out-of-flow and invisible: it does not add a blank row or move message layout. */
.chat-screen .chat-history::after{
 content:'';position:absolute;top:0;left:0;width:1px;height:calc(100% + 1px);
 pointer-events:none;
}
.history-jump{position:absolute;right:12px;bottom:calc(var(--chat-composer-height,60px) + 12px);z-index:3;display:grid;place-items:center;width:40px;height:40px;border-radius:50%;background:var(--surface);color:var(--muted);box-shadow:0 1px 5px #0002;padding:8px;}
.history-jump[hidden]{display:none;}
.history-jump svg{width:24px;height:24px;}
.history-jump-count{position:absolute;top:-8px;right:-2px;min-width:19px;height:19px;line-height:19px;padding:0 4px;border-radius:10px;background:var(--accent);color:white;font-size:11px;font-weight:600;}