html, body {
  margin: 0;
  padding: 0;
  background-color: transparent;
  color: #ffffff;
  height: 100vh;
  width: 100vw;
  display: flex;
  justify-content: center;
  align-items: center;
  font-family: Arial, sans-serif;
}

.clock-container {
  text-align: center;
  background-color: transparent;
}

.clock, .date {
  font-family: 'BIZ UDGothic', sans-serif;
  text-shadow: 2px 2px 4px rgba(0,0,0,0.7);
}

.clock {
  font-size: 10vw;
  background-color: transparent;
}

.date {
  font-size: 5vw;
  margin-top: 10px;
  display: block;
}

.settings-toggle {
  position: absolute;
  top: 10px;
  left: 10px;
  font-size: 1.5em;
  cursor: pointer;
  user-select: none;
}

.control-panel {
  position: absolute;
  top: 40px;
  left: 10px;
  display: none;
  background-color: #fff;
  color: #000;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 8px;
  box-shadow: 0 0 5px rgba(0,0,0,0.2);
}

input[type="color"] {
  width: 100px;
  height: 30px;
  border: none;
  cursor: pointer;
}

.background {
  position: fixed;
  top: 0; bottom: 0; left: 0; right: 0;
  background-size: cover;
  background-position: center center;
  background-repeat: no-repeat;
  background-color: black;
  z-index: -1;
  filter: brightness(0.6);
}

@media screen and (max-width: 480px) {
  .clock {
    font-size: 16vw;
  }

  .date {
    font-size: 8vw;
  }
}