* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont;
  background: linear-gradient(180deg, #020617, #0f172a);
  color: #e5e7eb;
}

header {
  padding: 16px;
  text-align: center;
  font-size: 22px;
  font-weight: 700;
}

.card {
  background: #020617;
  margin: 12px;
  padding: 16px;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.4);
}

.card h2 {
  margin: 0 0 10px;
  font-size: 18px;
}

.timer {
  font-size: 40px;
  text-align: center;
  margin: 16px 0;
}

.btn-group {
  display: flex;
  gap: 10px;
}

button {
  flex: 1;
  padding: 12px;
  border-radius: 12px;
  border: none;
  background: #38bdf8;
  font-size: 16px;
  font-weight: 600;
}

input {
  width: 100%;
  padding: 10px;
  margin-top: 8px;
  border-radius: 10px;
  border: none;
}