body {
  margin: 0;
  background: linear-gradient(to bottom, #b30000, #800000);
  font-family: "Segoe UI", sans-serif;
  color: white;
  text-align: center;
  padding: 20px;
}

.envelope {
  margin-top: 100px;
  cursor: pointer;
}

.envelope img {
  width: 250px;
}

.click-hint {
  margin-top: 10px;
  font-size: 18px;
  color: #ffeaea;
}

.letter {
  display: none;
  margin-top: 30px;
  padding: 30px;
  background: #fffaf0;
  color: #440000;
  border-radius: 20px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  box-shadow: 0 0 20px rgba(255, 255, 255, 0.4);
}

.letter .content p {
  font-size: 18px;
  line-height: 1.6;
}

.firma {
  margin-top: 20px;
  font-weight: bold;
  color: #b30000;
}

.hidden {
  display: none;
}