body { margin: 0; background: black; color: white; font-family: Arial, sans-serif; text-align: center; }
#container{ width:100vw; height:100vh; display:flex; flex-direction:column; justify-content:center; align-items:center; gap:20px; }
.hidden{ display:none; }

#instructions{ font-size: 26px; max-width: 900px; line-height: 1.5; }
#instructions ul{ text-align:left; font-size: 24px; }

#task{ position: relative; width:100vw; height:100vh; }

#fixation{
  position:absolute; left:50%; top:50%;
  transform: translate(-50%,-50%);
  font-size: 90px; z-index: 1;
}

#stimulus{
  position:absolute;
  width: 8vmin; height: 8vmin;
  min-width: 36px; min-height: 36px;
  max-width: 60px; max-height: 60px;
  border-radius: 50%;
  transform: translate(-50%,-50%);
  z-index: 2;
}

button{ padding: 12px 18px; font-size: 18px; border-radius: 10px; border:none; cursor:pointer; }