tate.skips += 1;
        feedback('Skipped', false);
        updateStatsUI();
        nextProblem();
      }

      function feedback(msg, ok) {
        els.feedback.textContent = msg;
        els.feedback.className = 'feedback ' + (ok ? 'ok' : 'no');
        flash(ok ? '#19c37d22' : '#ef444422');
      }

      function flash(color) {
        const el = document.querySelector('.problem');
        const old = el.style.boxShadow;
        el.style.boxShadow = `0 0 0 9999px ${color} inset, 0 6px 20px var(--sha