countdown.md
In countdown: A Countdown Timer for HTML Presentations, Documents, and Web Apps

countdown css template

.countdown {
  background: inherit;
  position: absolute;
  cursor: pointer;
  font-size: 3rem;
  line-height: 1;
  border-color: #ddd;
  border-width: 3px;
  border-style: solid;
  border-radius: 15px;
  box-shadow: 0px 4px 10px 0px rgba(50, 50, 50, 0.4);
  -webkit-box-shadow: 0px 4px 10px 0px rgba(50, 50, 50, 0.4);
  margin: 0;
  padding: 12px;
  text-align: center;
  z-index: 10;
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
          user-select: none;
}
.countdown {
  display: flex;
  align-items: center;
  justify-content: center;
}
.countdown .countdown-time {
  background: none;
  font-size: 100%;
  padding: 0;
}
.countdown-digits {
  color: inherit;
}
.countdown.running {
  border-color: #2A9B59FF;
  background-color: #43AC6A;
}
.countdown.running .countdown-digits {
  color: #002F14FF;
}
.countdown.finished {
  border-color: #DE3000FF;
  background-color: #F04124;
}
.countdown.finished .countdown-digits {
  color: #4A0900FF;
}
.countdown.running.warning {
  border-color: #CEAC04FF;
  background-color: #E6C229;
}
.countdown.running.warning .countdown-digits {
  color: #3A2F02FF;
}

.countdown.running.blink-colon .countdown-digits.colon {
  opacity: 0.1;
}

/* ------ Controls ------ */
.countdown:not(.running) .countdown-controls {
  display: none;
}

.countdown-controls {
  position: absolute;
  top: -0.5rem;
  right: -0.5rem;
  left: -0.5rem;
  display: flex;
  justify-content: space-between;
  margin: 0;
  padding: 0;
}

.countdown-controls > button {
  font-size: 1.5rem;
  width: 1rem;
  height: 1rem;
  display: inline-block;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-family: monospace;
  padding: 10px;
  margin: 0;
  background: inherit;
  border: 2px solid;
  border-radius: 100%;
  transition: 50ms transform ease-in-out, 150ms opacity ease-in;
  --countdown-transition-distance: 10px;
}

.countdown .countdown-controls > button:last-child {
  transform: translate(calc(-1 * var(--countdown-transition-distance)), var(--countdown-transition-distance));
  opacity: 0;
  color: #002F14FF;
  background-color: #43AC6A;
  border-color: #2A9B59FF;
}

.countdown .countdown-controls > button:first-child {
  transform: translate(var(--countdown-transition-distance), var(--countdown-transition-distance));
  opacity: 0;
  color: #4A0900FF;
  background-color: #F04124;
  border-color: #DE3000FF;
}

.countdown.running:hover .countdown-controls > button,
.countdown.running:focus-within .countdown-controls > button{
  transform: translate(0, 0);
  opacity: 1;
}

.countdown.running:hover .countdown-controls > button:hover,
.countdown.running:focus-within .countdown-controls > button:hover{
  transform: translate(0, calc(var(--countdown-transition-distance) / -2));
  box-shadow: 0px 2px 5px 0px rgba(50, 50, 50, 0.4);
  -webkit-box-shadow: 0px 2px 5px 0px rgba(50, 50, 50, 0.4);
}

.countdown.running:hover .countdown-controls > button:active,
.countdown.running:focus-within .countdown-controls > button:active{
  transform: translate(0, calc(var(--coutndown-transition-distance) / -5));
}

/* ----- Fullscreen ----- */
.countdown.countdown-fullscreen {
  z-index: 0;
}

.countdown-fullscreen.running .countdown-controls {
  top: 1rem;
  left: 0;
  right: 0;
  justify-content: center;
}

.countdown-fullscreen.running .countdown-controls > button + button {
  margin-left: 1rem;
}