:root {
  --bg-color: #000;
  --clock-color: #fff;
  --font-family: "Arial", "Helvetica", "メイリオ", "ヒラギノ角ゴ Pro W3", sans-serif;
  --fade-speed: 0.5s;
}
html,body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--bg-color);
  color: var(--clock-color);
  font-family: --font-family;
}
.hidden{
  opacity: 0;
}
.material-symbols-rounded {
  font-variation-settings:
  'FILL' 1,
  'wght' 400,
  'GRAD' 0,
  'opsz' 24
}
  
#clock {
  display: flex;
  flex-direction: column;
  align-items: center;  
  transition: opacity var(--fade-speed) ease;
}
#time, #date {
  text-align: center;
  user-select: none;
}
#date{
  font-size: clamp(32px, 4vw, 64px)
}
#time {
  font-size: clamp(80px, 10vw, 160px)
}
  
#settings{
  transition: opacity var(--fade-speed) ease;
}
#settings summary{
  width: 48px;
  height: 48px;
  top: 24px;
  right: 24px;
  position: fixed;
  background: rgba(66, 66, 66, .7);
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer
}
#settings-items{
  display: flex;
  top: 24px;
  right: 88px;
  position: fixed;
  width: 240px;
  flex-direction: column;
  padding: 16px;
  border-radius: 8px;
  background: rgba(66, 66, 66, .7);
}
#settings-items label{
  display: flex;
  align-items: center;
  margin-bottom: 12px;
  gap: 0 8px;
}
#settings-items input[type="color"], #settings-items select{
  flex:1;
}