style.css

:root {
  font-family: Inter, system-ui, Avenir, Helvetica, Arial, sans-serif;
  line-height: 1.5;
  font-weight: 400;

  color-scheme: light dark;
  color: rgba(255, 255, 255, 0.87);
  background-color: #242424;

  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  display: flex;
  place-items: center;
  min-width: 320px;
  min-height: 100vh;
}

h1 {
  font-size: 3.2em;
  line-height: 1.1;
}

.row {
  display: flex;
  justify-content: space-evenly;
}

#required {
  justify-content: center;
}

.row:not(:first-of-type) {
  margin-top: 20px;
}

.timeParts {
  display: flex;
  justify-content: space-evenly;
  flex-direction: column;
  align-items: center;
}

label, input, p {
  width: 150px;
  height: 25px;
  margin: 0px;
  text-align: center;
}

#app {
  max-width: 1280px;
  margin: 0 auto;
  text-align: center;
  padding: 20px;
  padding-top: 0px;

  border-radius: 10px;
  border: 1px black solid;
  box-shadow: 5px 5px 5px black;
}

#apps {
  display: flex;
}

#timeCalculator, #timeConverter {
  width: 350px;
}

#timeConverter {
  border-left: 1px white solid;
}

@media (prefers-color-scheme: light) {
  :root {
    color: #213547;
    background-color: #ffffff;
  }
}