talking-timer.css

body {
  font-family: Arial, Helvetica, sans-serif;
}
.hide {
  display: none;
}
.hide + .colon {
  display: none;
}
.duration {
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  justify-content: center;
  align-items: stretch;
}
.duration label {
  display: block;
  font-weight: bold;
  font-family: Verdana, Geneva, Tahoma, sans-serif;
  text-align: center;
}
.duration input {
  display: block;
  font-size: 4rem;
  width: 6rem;
  border: none;
  text-align: right;
  padding: 0 0.2rem;
}
ul {
  column-width: 20rem;
  padding: 0;
  margin: 0.5rem 0;
  column-gap: 5%;
}
li {
  list-style-type: none;
  padding: 0;
  -webkit-column-break-inside: avoid-column
}
label.checkbox {
  display: block;
  padding: 0.5rem 0.5rem 0.3rem 2.15rem;
  text-indent: -1.65rem;
}
label + span {
  display: block;
  padding: 0 0.5rem 0.5rem 2.15rem;
}
input[type=text] {
  font-family: 'Courier New', Courier, monospace;
  padding: 0.3rem 0.5rem;
  display: inline-block;
  width: 30rem;
}
.colon {
  align-items: baseline;
  font-size: 4rem;
  padding: 1.1rem 0.1rem 0;
}

.sub {
  display: block;
  font-size: 0.9rem;
  font-weight: normal;
}

talking-timer {
  display: block;
  margin: 2rem auto;
  max-width: 30rem;
  width: 100%;
  font-size: 90%;
  border: 0.05em solid #ccc;
  padding: 0;
  position: relative;
}

.timer-wrap {
  align-items: stretch;
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  justify-content: space-between;
  margin: auto;
  width: 100%;
}

@media screen and (min-width: 60rem) {
  .timer-wrap {
    flex-direction: row;
    align-items: center;
  }
}