:root{color:#1f2937;background:#f5f7fb;font-family:Segoe UI,Apple SD Gothic Neo,sans-serif}*{box-sizing:border-box}body{margin:0;min-height:100vh;background:linear-gradient(180deg,#f0f4ff,#f8fafc)}.app{max-width:960px;margin:0 auto;padding:24px}.header{margin-bottom:16px}.header h1{margin:0 0 6px;font-size:1.6rem}.header p{margin:0;color:#4b5563}.chat-panel{border:1px solid #dbe4ff;background:#fff;border-radius:12px;display:flex;flex-direction:column;min-height:70vh}.messages{flex:1;padding:16px;overflow:auto;display:flex;flex-direction:column;gap:10px}.message{padding:10px 12px;border-radius:10px;display:flex;flex-direction:column;gap:4px;white-space:pre-wrap}.message.user{background:#e9f2ff;border:1px solid #cfe3ff;align-self:flex-end;max-width:80%}.message.assistant{background:#f4f7f9;border:1px solid #e5e7eb;max-width:80%}.message.system{background:#fff7ed;border:1px solid #fed7aa}.composer{border-top:1px solid #e5e7eb;padding:12px;display:grid;grid-template-columns:1fr auto auto;gap:8px}.composer input{border:1px solid #cbd5e1;border-radius:8px;padding:10px}.composer button{border:0;border-radius:8px;background:#1d4ed8;color:#fff;padding:10px 14px;cursor:pointer}.composer button:disabled{opacity:.6;cursor:not-allowed}.hidden{display:none}@media (max-width: 768px){.app{padding:12px}.composer{grid-template-columns:1fr}}