body {
  font-family: system-ui, sans-serif;
  background: #f5f5f5;
  text-align: center;
}

.screen {
  display: none;
  padding: 30px;
}

.screen.active {
  display: block;
}

.buttons button {
  margin: 10px;
  padding: 12px 24px;
  font-size: 18px;
  border-radius: 8px;
  border: none;
  background: #333;
  color: #fff;
  cursor: pointer;
}

.buttons button:hover {
  background: #555;
}

#zero-btn {
  display: none;
  background: linear-gradient(135deg, #000, #444);
  color: #ffd700;
  font-weight: bold;
}

#question {
  font-size: 32px;
  margin: 30px 0;
}

input {
  font-size: 18px;
  padding: 8px;
}

.status {
  display: flex;
  justify-content: space-between;
}

table {
  margin: 20px auto;
  border-collapse: collapse;
  width: 80%;
}

th, td {
  border: 1px solid #999;
  padding: 6px;
}