body { font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; margin:0; background:#f8fafc; color:#0f172a; }
.card { background:white; border:1px solid #e2e8f0; border-radius:16px; padding:18px; box-shadow:0 10px 30px rgba(15,23,42,.06); }
.chat-layout { display:grid; grid-template-columns: 300px 1fr 320px; gap:16px; padding:16px; }
.chat-list,.chat-room,.customer-panel { min-height:70vh; }
.chat-bubble { max-width:70%; padding:10px 14px; border-radius:16px; margin:8px 0; }
.chat-bubble.staff { background:#2563eb; color:white; margin-left:auto; }
.chat-bubble.customer { background:#e2e8f0; }
.installment-widget { border:1px solid #dbeafe; background:#eff6ff; border-radius:16px; padding:14px; }
.installment-row { background:white; border-radius:12px; padding:10px; margin-top:8px; }
@media(max-width: 900px) { .chat-layout { grid-template-columns:1fr; } .customer-panel { display:none; } }