body {
  background: #cfcfcf;
  font-family: sans-serif;
}

.app {
  width: 700px;
  margin: 40px auto;
}

/* SECUENCIADOR */
.sequencer {
  background: red;
  padding: 10px;
}

.track {
  display: flex;
  align-items: center;
  background: orange;
  margin-bottom: 6px;
  padding: 6px;
}

.track-label {
  width: 24px;
  height: 24px;
  background: purple;
  margin-right: 10px;
}

.steps {
  display: flex;
  gap: 5px;
  overflow-x: auto;
}

.step {
  width: 30px;
  height: 30px;
  background: yellow;
  cursor: pointer;
  flex-shrink: 0;
}

.step.active {
  background: #ffcc00;
  outline: 2px solid #000;
}

.step.playing {
  outline: 3px solid red;
}

/* CONTROLES */
.controls {
  margin-top: 20px;
  background: green;
  padding: 10px;
  display: flex;
  align-items: center;
  gap: 10px;
}

#bpm {
  width: 250px;
}

button {
  width: 40px;
  height: 40px;
  font-size: 18px;
}