body {
  margin: 0;
  font-family: "Meiryo", sans-serif;
  background-color: #eafbe4;
}
main {
  padding: 0.5em;
}
.controls {
  display: flex;
  justify-content: center;
  gap: 1em;
  margin-bottom: 0.5em;
  flex-wrap: wrap;
}
.channel {
  margin-bottom: 1em;
}
.channel-info {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2em;
  margin-bottom: 0.2em;
}
.channel-info .metric {
  text-align: center;
}
.channel-info .voltage {
  font-size: 1.6rem;
  font-weight: bold;
  color: #003366;
}
.channel-info .metric:not(.voltage) {
  font-size: 1.2rem;
}
.channel-info button {
  padding: 0.4em 1em;
}
.graph-container {
  display: flex;
  justify-content: center;
}
.graph {
  width: 100%;
  max-width: 900px;
  height: auto;
  background: #fff;
  border: 1px solid #ccc;
  box-sizing: border-box;
}
footer {
  text-align: center;
  padding: 0.5em;
}