body {
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f0fdf4;
  color: #333;
}

header {
  text-align: center;
  padding: 1em;
  background-color: #4caf50;
  color: white;
}

#calendar {
  max-width: 90%;
  margin: 20px auto;
  background: white;
  padding: 1em;
  border-radius: 12px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

.popup {
  display: none;
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background-color: rgba(0, 0, 0, 0.4);
  justify-content: center;
  align-items: center;
  z-index: 999;
}

.popup-inner {
  background: white;
  padding: 2em;
  border-radius: 10px;
  width: 90%;
  max-width: 400px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.popup-inner label, .popup-inner select, .popup-inner input, .popup-inner textarea {
  display: block;
  width: 100%;
  margin: 0.5em 0;
}

.popup-inner button {
  padding: 0.8em;
  background-color: #4caf50;
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  margin-top: 1em;
}

.close-btn {
  float: right;
  font-size: 24px;
  cursor: pointer;
}