:root {
  --bg-color: #ffffff;
  --text-color: #000000;
  --panel-bg: #f0f0f0;
  --panel-border: #ccc;
  --key-white: #ffffff;
  --key-black: #333333;
  --key-white-active: #dddddd;
  --key-black-active: #555555;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #222222;
    --text-color: #eeeeee;
    --panel-bg: #333333;
    --panel-border: #555555;
    --key-white: #444444;
    --key-black: #000000;
    --key-white-active: #666666;
    --key-black-active: #333333;
  }
}

body {
  margin: 0;
  font-family: sans-serif;
  background: var(--bg-color);
  color: var(--text-color);
}

header {
  padding: 1rem;
  background: var(--panel-bg);
  border-bottom: 1px solid var(--panel-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.channel-selector label {
  margin-right: 0.5rem;
}

.channels {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1rem;
  padding: 1rem;
}

.channel {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 4px;
  padding: 0.5rem;
}

.channel h2 {
  margin: 0 0 0.5rem 0;
  font-size: 1.1rem;
}

.channel label {
  display: block;
  margin: 0.25rem 0;
  font-size: 0.9rem;
}

.channel input,
.channel select {
  width: 100%;
  margin-top: 0.25rem;
}

.channel fieldset {
  margin: 0.5rem 0;
  border: 1px solid var(--panel-border);
  padding: 0.5rem;
}

.channel fieldset legend {
  font-size: 0.9rem;
}

.filter-taps {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
  margin-top: 0.5rem;
}

.filter-taps input {
  width: 40px;
}

.keyboard {
  display: flex;
  user-select: none;
  padding: 0 1rem 1rem 1rem;
}

.key {
  position: relative;
  border: 1px solid var(--panel-border);
  box-sizing: border-box;
  cursor: pointer;
}

.key.white {
  width: 40px;
  height: 200px;
  background: var(--key-white);
  z-index: 1;
}

.key.black {
  width: 30px;
  height: 120px;
  background: var(--key-black);
  margin-left: -15px;
  margin-right: -15px;
  z-index: 2;
}

.key.active.white {
  background: var(--key-white-active);
}

.key.active.black {
  background: var(--key-black-active);
}