countdown.css

/* general styling */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  margin: 0;
}

body {
  align-items: center;
  background-image: url("marks.png");
  background-repeat: repeat;
  background-position: 182% 7%; /* No idea what this means */
  background-blend-mode: hard-light;
  background-color: #393939;
  display: flex;
  font-family: sans-serif;
  /*
  font-family: -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    Oxygen-Sans,
    Ubuntu,
    Cantarell,
    "Helvetica Neue",
    sans-serif;
  */
}

.container {
  color: #ddd;
  margin: 0 auto;
  text-align: center;
}

h1 {
  font-weight: normal;
  letter-spacing: .125rem;
  text-transform: uppercase;
  font-size: 2.0rem;
}

li {
  display: inline-block;
  font-size: 1.5em;
  list-style-type: none;
  padding: 1em;
  text-transform: uppercase;
}

li .remaining {
  display: block;
  font-size: 4.5rem;
}

.message {
  font-size: 4rem;
}

#content {
  display: none;
  padding: 1rem;
}

#countdown {
  margin-top: 4vh;
  margin-bottom: 7vh;
}

#lidays {
  min-width: 6.8rem;
}

#lihours {
  min-width: 9.5rem;
}

#liminutes {
  min-width: 10rem;
}

#liseconds {
  min-width: 12rem;
}

@media all and (max-width: 768px) {
  h1 {
    font-size: 1.5rem;
  }

  li {
    font-size: 1.125rem;
    padding: .75rem;
  }

  li .remaining {
    font-size: 3.375rem;
  }

  #lidays {
    min-width: 5.1rem;
  }

  #lihours {
    min-width: 6.375rem;
  }

  #liminutes {
    min-width: 7.5rem;
  }

  #liseconds {
    min-width: 9rem;
  }
}

@media all and (max-width: 430px) {
  h1 {
    font-size: 2.0rem;
  }

  li {
    font-size: 0.900rem;
    padding: 0.45rem;
  }

  li .remaining {
    font-size: 3.375rem;
  }

  #countdown {
    margin-top: 3vh;
    margin-bottom: 4vh;
  }

  #lidays {
    min-width: 3.6rem;
  }

  #lihours {
    min-width: 4.67rem;
  }

  #liminutes {
    min-width: 5.67rem;
  }

  #liseconds {
    min-width: 6.1rem;
  }
}

@media all and (max-width: 330px) {
  /* For the iPhone 5/SE */

  h1 {
    font-size: 2.0rem;
  }

  li {
    font-size: 0.900rem;
    padding: 0.45rem;
  }

  li .remaining {
    font-size: 3.375rem;
  }

  #countdown {
    margin-top: 3vh;
    margin-bottom: 4vh;
  }

  #lidays {
    min-width: 0.6rem;
  }

  #lihours {
    min-width: 4.67rem;
  }

  #liminutes {
    min-width: 5.27rem;
  }

  #liseconds {
    min-width: 6.1rem;
  }
}

/* From https://geekunicorn.com/create-a-script-text-with-glitter-overlay-on-wordpress/ (God bless the unicorn!) */
.glitter-script {
  font-family: -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    Oxygen-Sans,
    Ubuntu,
    Cantarell,
    "Helvetica Neue",
    sans-serif;
  padding: 0.6em 0.2em;
  background-image: url("glitter-rainbow.jpg");
  background-repeat: no-repeat;
  background-size: cover;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  box-decoration-break: clone;
  -webkit-box-decoration-break: clone;
}