:root{--bg:#0f1117;--bg-elevated:#171a22;--bg-hover:#1f2430;--border:#2a3142;--text:#eef1f8;--text-muted:#9aa4b8;--accent:#6ea8fe;--accent-strong:#4d8dff;--user-bubble:#1f3a5f;--assistant-bubble:#1a1f2b;--success:#3ecf8e;--danger:#ff6b6b;--radius:14px;--shadow:0 12px 40px rgba(0,0,0,0.35)}*{box-sizing:border-box}body,html{margin:0;padding:0;min-height:100%;background:var(--bg);color:var(--text);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}a{color:var(--accent);text-decoration:none}button,input,select,textarea{font:inherit}.app-shell{display:grid;grid-template-columns:280px 1fr;min-height:100vh}.sidebar{background:var(--bg-elevated);border-right:1px solid var(--border);display:flex;flex-direction:column;padding:16px;gap:12px}.sidebar-header{display:flex;align-items:center;justify-content:space-between;gap:8px}.brand{font-size:1.1rem;font-weight:700}.sidebar-actions{display:grid;grid-gap:8px;gap:8px}.conversation-list{flex:1 1;overflow:auto;display:grid;grid-gap:6px;gap:6px}.conversation-item{text-align:left;background:transparent;border:1px solid transparent;color:var(--text);border-radius:10px;padding:10px 12px;cursor:pointer}.conversation-item.active,.conversation-item:hover{background:var(--bg-hover);border-color:var(--border)}.chat-main{display:grid;grid-template-rows:auto 1fr auto auto;min-height:100vh}.topbar{align-items:center;justify-content:space-between;padding:16px 20px;border-bottom:1px solid var(--border);background:rgba(15,17,23,.85);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.topbar,.usage-bar{display:flex;gap:12px}.usage-bar{flex-wrap:wrap;font-size:.85rem;color:var(--text-muted)}.messages{overflow:auto;padding:24px;display:flex;flex-direction:column;gap:16px}.message{max-width:820px;width:-moz-fit-content;width:fit-content;padding:14px 16px;border-radius:var(--radius);line-height:1.55;white-space:pre-wrap}.message.user{align-self:flex-end;background:var(--user-bubble)}.message.assistant{align-self:flex-start;background:var(--assistant-bubble);border:1px solid var(--border)}.message-meta{margin-top:8px;font-size:.75rem;color:var(--text-muted)}.composer{padding:16px 20px 20px;border-top:1px solid var(--border);background:var(--bg-elevated)}.composer-row{display:grid;grid-template-columns:180px 1fr auto;grid-gap:10px;gap:10px;align-items:end}.composer textarea{width:100%;min-height:72px;max-height:180px;resize:vertical;background:var(--bg);color:var(--text);border:1px solid var(--border);border-radius:12px;padding:12px 14px}.btn{border:none;border-radius:10px;padding:10px 14px;cursor:pointer;background:var(--accent-strong);color:white}.btn.secondary{background:var(--bg-hover);color:var(--text);border:1px solid var(--border)}.btn:disabled{opacity:.6;cursor:not-allowed}.auth-panel,.empty-state{max-width:420px;margin:auto;padding:32px;background:var(--bg-elevated);border:1px solid var(--border);border-radius:18px;box-shadow:var(--shadow)}.auth-panel input,.auth-panel select,.composer select,.sidebar select{width:100%;background:var(--bg);color:var(--text);border:1px solid var(--border);border-radius:10px;padding:10px 12px}.auth-panel .stack,.auth-panel form{display:grid;grid-gap:10px;gap:10px}.source-panel{padding:0 20px 12px}.source-panel details{background:var(--bg-elevated);border:1px solid var(--border);border-radius:12px;padding:10px 12px}.pill{display:inline-flex;align-items:center;gap:6px;padding:4px 10px;border-radius:999px;background:var(--bg-hover);color:var(--text-muted);font-size:.75rem}@media (max-width:900px){.app-shell{grid-template-columns:1fr}.sidebar{display:none}.composer-row{grid-template-columns:1fr}}