html,body,#root{height:100%}*{box-sizing:border-box}body{margin:0;font-family:Arial,sans-serif}.app{display:flex;height:100vh;background:#f7f7f8}.sidebar{width:260px;background:#202123;color:#fff;padding:20px}.sidebar-header h2{margin-top:0}.new-session-button{width:100%;padding:12px;border:1px solid #565869;background:transparent;color:#fff;border-radius:6px;cursor:pointer;font-size:15px}.new-session-button:hover{background:#343541}.session-list{margin-top:20px}.session-item{padding:12px;border-radius:6px;cursor:pointer;margin-bottom:5px}.session-item:hover,.session-item.active{background:#343541}.chat-container{flex:1;display:flex;flex-direction:column}.chat-header{padding:20px;background:#fff;border-bottom:1px solid #ddd}.chat-header h2{margin:0}.messages{flex:1;padding:30px;overflow-y:auto}.empty-chat{text-align:center;color:#777;margin-top:100px}.welcome{margin:auto;text-align:center}.welcome h1{font-size:32px}.start-button{padding:12px 20px;border:none;border-radius:6px;cursor:pointer}.chat-input-container{display:flex;padding:20px;background:#fff;border-top:1px solid #ddd}.chat-input-container input{flex:1;padding:14px;font-size:16px;border:1px solid #ccc;border-radius:6px}.chat-input-container button{margin-left:10px;padding:0 20px;border:none;border-radius:6px;cursor:pointer}.message{max-width:75%;margin-bottom:20px;padding:12px 16px;border-radius:10px}.message p{margin:5px 0 0;white-space:pre-wrap}.message.user{margin-left:auto;background:#e5e7eb}.message.assistant{margin-right:auto;background:#fff;border:1px solid #ddd}