.messaging-shell{display:grid;grid-template-columns:350px 1fr;height:calc(100vh - 160px);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);overflow:hidden;box-shadow:var(--shadow-soft)}.contacts-list{border-right:1px solid var(--border);overflow-y:auto;-webkit-overflow-scrolling:touch;overscroll-behavior-y:contain}.contact-item{padding:20px 24px;border-bottom:1px solid var(--border);cursor:pointer;transition:.2s}.contact-item:hover,.contact-item.active{background:#1e293b66}.contact-item.active{border-left:4px solid var(--primary)}.chat-view{display:flex;flex-direction:column}.chat-header{padding:20px 32px;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between}.chat-messages{flex:1;padding:32px;overflow-y:auto;scroll-behavior:smooth;-webkit-overflow-scrolling:touch;overscroll-behavior-y:contain;display:flex;flex-direction:column;gap:20px}.message{max-width:70%;padding:16px 20px;border-radius:20px;font-size:.95rem}.message.sent{align-self:flex-end;background:var(--primary);color:#fff;border-bottom-right-radius:4px}.message.received{align-self:flex-start;background:#1e293b99;color:var(--text-dark);border-bottom-left-radius:4px;border:1px solid var(--border)}.chat-input-area{padding:24px 32px;border-top:1px solid var(--border);display:flex;gap:16px}@media(max-width:900px){.messaging-shell{grid-template-columns:1fr;height:auto;min-height:calc(100vh - 120px)}.contacts-list{height:300px;border-right:none;border-bottom:1px solid var(--border)}.chat-view{height:500px}.chat-header{padding:16px 20px}.chat-messages{padding:20px}.chat-input-area{padding:16px 20px}}