body {
  font-family: sans-serif;
  margin: 0;
  padding: 1em;
  background-color: #f5f5f5;
}
main {
  max-width: 600px;
  margin: auto;
  background: white;
  padding: 1em;
  border-radius: 4px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
.form-group {
  margin-bottom: 1em;
  display: flex;
  flex-direction: column;
}
.form-group-inline {
  display: flex;
  align-items: center;
  gap: 0.5em;
}
.time-inputs {
  display: flex;
  align-items: center;
  gap: 0.25em;
}
label {
  font-weight: bold;
}
small {
  color: #555;
}
#error {
  color: red;
  margin-top: 1em;
}
@media (max-width: 500px) {
  .time-inputs input {
    width: 4em;
  }
}