/* Mental Arithmetic */
.ns-q { font-family: var(--display); font-size: clamp(42px, 12vw, 64px); font-weight: 800; margin: 34px 0 34px; font-variant-numeric: tabular-nums; }
.ns-q.in { animation: ns-in .2s ease-out; }
@keyframes ns-in { from { transform: translateY(10px); opacity: 0; } }
.ns-pad { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; width: 100%; max-width: 440px; }
.ns-btn { position: relative; min-height: 74px; border-radius: 18px; font-family: var(--display); font-size: 30px; font-weight: 800; font-variant-numeric: tabular-nums;
  background: var(--tile-top); color: var(--text); border: 1px solid var(--glass-edge); box-shadow: var(--lift); cursor: pointer; transition: transform .1s; }
.ns-btn:hover { transform: translateY(-2px); }
.ns-btn:active { transform: translateY(2px); }