div.circuit-container {
  max-width: 96%;
  width: auto;
  margin: 5px 0 5px 0;
  position: relative;
}

img.circuit-schematic {
  width: 100%;
  height: auto;
}

.circuit-input {
  -webkit-user-select: none;
  transition: all 1s ease;
  background: white;
  border: 1px solid;
  border-radius: 5px;
  position: absolute;
  font-family: courier;
  font-size: 1.5em;
  font-weight: bold;
  text-align: center;
}
.circuit-input:active {
    background-color: yellow;
    -webkit-transition: background-color 0.1s ease-out;
}

.circuit-output {
  background: none;
  position: absolute;
  font-family: courier;
  font-size: 1.5em;
  font-weight: bold;
  text-align: center;
}

.circuit-intern {
  background: none;
  border: none;
  position: absolute;
  font-family: courier;
  font-size: 1em;
  font-weight: regular;
  text-align: center;
}

.circuit-container > .flash {
  -webkit-animation-name: circuit-flash-animation;
  -webkit-animation-duration: 1s;
  -webkit-animation-timing-function: ease-in-out;
}

@-webkit-keyframes circuit-flash-animation {
  from {
    background: yellow;
  }
  to {
    background: default;
  }
}