:root{color-scheme:light;font-family:Inter,Arial,sans-serif}*{box-sizing:border-box}body{margin:0;background:#f5f7fb;color:#222}body,main{min-height:100vh}main{display:flex;align-items:center;justify-content:center;padding:1rem}.chat-shell{width:100%;max-width:760px;background:#fff;border:1px solid #e5e9f0;border-radius:14px;box-shadow:0 12px 30px rgba(17,24,39,.08);overflow:hidden}.chat-header{padding:1rem 1.25rem;border-bottom:1px solid #eef2f7;font-weight:600}.messages{height:420px;overflow-y:auto;padding:1rem;display:flex;flex-direction:column;gap:.75rem;background:#fcfdff}.message{padding:.65rem .85rem;border-radius:10px;line-height:1.4;max-width:80%;white-space:pre-wrap}.message.user{align-self:flex-end;background:#dce8ff}.message.assistant{align-self:flex-start;background:#edf2f7}.composer{border-top:1px solid #eef2f7;padding:1rem;display:grid;grid-gap:.75rem;gap:.75rem}.row{display:flex;gap:.5rem}input[type=text]{flex:1 1;border:1px solid #cfd8e3;border-radius:8px;padding:.65rem .8rem;font-size:1rem}button{border:0;border-radius:8px;padding:.65rem 1rem;background:#2563eb;color:#fff;font-weight:600;cursor:pointer}button:disabled{opacity:.6;cursor:not-allowed}.status{font-size:.9rem;color:#475569}.error{color:#c1121f}