styles.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: sans-serif;
  color: #fff;
}

body {
  display: flex;
  justify-content: center;
  align-items: center; /*it will make it vertically center but we 
    need to give height first
    */
  min-height: 100vh; /*it will make it center*/
  background-color: #008000;
}

.container {
  position: relative;
}
.clock {
  width: 300px;
  height: 300px;
  border-radius: 50%;
  background-color: rgba(255, 0, 0);
  border: 2px solid rgba(255, 0, 0, 0.25);
  box-shadow: 0px 0px 30px rgba(0, 0, 0, 0.9);
  display: flex;
  justify-content: center;
  align-items: center;
}

.clock span {
  position: absolute;
  transform: rotate(
    calc(30deg * var(--i))
  ); /*here var() is a custom css varialbe and as there are 12 hours
    and it is 360 degree circle we can 360/12 = 30 degree and we are multiplying
    it var(--i) if i = 3 than it will 30 * 3 degree*/
  inset: 12px; /*if not set inset it will not bring the digits in center*/
  text-align: center; /*text-align center will bring digits inside the circle border*/
}

.clock span b {
  /* we need to transform b tag transform rotate to negative value -30deg to 
    make all the digits  vertically straight*/
  transform: rotate(calc(-30deg * var(--i)));
  display: inline-block; /*we need to inline-block because it is default is block*/
  font-size: 20px;
}

.clock::before {
  position: absolute;
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: #fff;
}

.hand {
  position: absolute;
  display: flex;
  justify-content: center;
  align-items: flex-end;
}

.hand i {
  position: absolute;
  background-color: var(--clr);
  width: 4px;
  height: var(--h);
  border-radius: 8px;
}