/* tiny inline styles so you can test quickly */
    body { font-family: system-ui, Arial; display:flex; align-items:center; justify-content:center; height:100vh; background:#111; color:#eee; }
    .calc { width:320px; background:#222; padding:16px; border-radius:8px; box-shadow:0 6px 20px rgba(0,0,0,0.6); }
    #display { height:56px; background:#000; color:#0f0; padding:12px; font-size:20px; border-radius:6px; margin-bottom:12px; overflow:hidden; white-space:nowrap; text-overflow:ellipsis; }
    .row { display:flex; gap:8px; margin-bottom:8px; }
    button { flex:1; padding:14px 8px; font-size:18px; border-radius:6px; border:0; cursor:pointer; background:#333; color:#fff; }
    button.op { background:#ff9500; color:#000; }
    button.equal { background:#0a84ff; }
    button.clear { background:#ff3b30; }