:root{--bg:#fff;--bg-elev:#f7f7f8;--bg-sidebar:#f9f9f9;--border:#e5e5e6;--text:#1f2023;--text-dim:#6b6c70;--accent:#10a37f;--accent-hover:#0e8f6f;--user-bubble:#eef6f3;--danger:#d9534f;--code-bg:#f2f2f3}:root[data-theme=dark]{--bg:#1a1b1e;--bg-elev:#25262b;--bg-sidebar:#141517;--border:#303136;--text:#ececf1;--text-dim:#9a9ba1;--accent:#10a37f;--accent-hover:#14b98f;--user-bubble:#2a3b36;--danger:#e5706b;--code-bg:#0e0f11}*{box-sizing:border-box}body,html{padding:0;margin:0;height:100%}body{background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;font-size:15px;line-height:1.55}button{font-family:inherit;cursor:pointer}input,select,textarea{font-family:inherit;font-size:inherit}a{color:var(--accent);text-decoration:none}.app{display:flex;height:100vh;overflow:hidden}.sidebar{width:270px;min-width:270px;background:var(--bg-sidebar);border-right:1px solid 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