body {
  background: #001f1f;
  color: white;
  font-family: 'Segoe UI', sans-serif;
  text-align: center;
  padding: 20px;
}

h1 {
  margin-bottom: 20px;
  font-size: 1.8em;
  color: #fff;
}

.tree {
  position: relative;
  margin: auto;
  width: 200px;
  height: 300px;
  background: linear-gradient(to bottom, #00703C, #004d2e);
  clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
  border: 2px solid #fff;
}

.star {
  position: absolute;
  top: -30px;
  left: 50%;
  transform: translateX(-50%);
  width: 30px;
  height: 30px;
  background: gold;
  clip-path: polygon(50% 0%, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
}

.lights {
  position: absolute;
  top: 20px;
  left: 0;
  width: 100%;
  display: flex;
  justify-content: space-around;
}

.lights li {
  width: 10px;
  height: 10px;
  background: red;
  border-radius: 50%;
  animation: twinkle 1s infinite alternate;
}

@keyframes twinkle {
  from { opacity: 0.3; }
  to { opacity: 1; }
}

.calendar {
  margin-top: 320px;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
  max-width: 300px;
  margin-left: auto;
  margin-right: auto;
}

.calendar div {
  padding: 10px;
  border: 1px solid #fff;
  border-radius: 5px;
  font-weight: bold;
  transition: transform 0.2s;
}

.locked {
  background: #333;
  color: #888;
  cursor: not-allowed;
}

.unlocked {
  background: #004d2e;
  color: white;
  cursor: pointer;
}

.unlocked:hover {
  transform: scale(1.05);
  background: #00703C;
}