styles.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
:root {
  --themecolor: black;
  --themeinvert: white;
  --coloncolor: red;
  --neon: rgb(255, 0, 0, 0.75);
}
@keyframes blink {
  0% {
    filter: opacity(1);
  }
  100% {
    filter: opacity(0);
  }
}
body {
  background-color: var(--themecolor);
  width: 100%;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}
.container {
  width: 100vw;
  height: 65vh;
  display: flex;
  align-items: center;
  justify-content: center;
}
.main-time {
  display: flex;
  width: 90%;
}
.main-time svg {
  height: 35vw;
  margin: 5px;
  filter: drop-shadow(0 0 1vw var(--neon));
}
.colon {
  font-family: Georgia;
  font-size: 27.5vw;
  vertical-align: middle;
  color: var(--coloncolor);
  text-shadow: 0 0 2vw var(--neon);
  animation: blink 1s both infinite ease-in;
}
.main-time svg g polygon {
  stroke: var(--coloncolor);
  stroke-width: 0.1px;
}
@media (min-width: 1200px) {
  .container {
    width: 100vw;
    height: 65vh;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .main-time {
    display: flex;
    width: 57.5%;
  }
  .main-time svg {
    height: 20vw;
    margin: 5px;
    filter: drop-shadow(0 0 0.5vw var(--neon));
  }
  .colon {
    font-family: Georgia;
    font-size: 17vw;
    vertical-align: middle;
    color: var(--coloncolor);
    text-shadow: 0 0 8px var(--neon);
    animation: blink 1s both infinite ease-in;
  }
  .main-time svg g polygon {
    stroke: var(--coloncolor);
    stroke-width: 0.1px;
  }
}