:root {
  --color-block: lightgray;
  --color-block-checked: lightgreen;

  --spacing-mouse: 0.25rem;
  --spacing-cat: 0.5rem;
  --spacing-dog: 1rem;
  --spacing-horse: 2rem;
  --spacing-elephant: 4rem;
}

body {
  margin: var(--spacing-dog);
}

.g-Bpm {
  display: block;
  margin-bottom: var(--spacing-dog);
}

.g-Input {
  margin-left: var(--spacing-dog);
}

.g-PlayStop {
  margin-bottom: var(--spacing-dog);
}

.g-Sequencer {
  margin-top: var(--spacing-dog);
}

.g-Sequencer__Buttons {
  margin-bottom: var(--spacing-dog);
  display: flex;
  gap: var(--spacing-dog);
}

.g-Sequencer__Blocks {
  display: flex;
  gap: var(--spacing-cat);
}

.g-Sequencer__Block {
  width: var(--spacing-horse);
  height: var(--spacing-horse);
  background-color: lightgray;
  cursor: pointer;
}

.g-Sequencer__Block:hover {
  filter: brightness(110%);
}

.g-Sequencer__Block--Checked {
  background-color: lightgreen;
}

.g-Sequencer__Block--Beat {
  animation: beat 0.2s linear;
}

@keyframes beat {
  0%   {transform: scale(100%);}
  30%  {transform: scale(105%);}
  100% {transform: scale(100%);}
}