app.css

* {
  padding: 0px;
  margin: 0px;
  box-sizing: border-box;
  user-select: none;
  -moz-user-select: none;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  font-size: 21px;
}

#wrapper {
  margin: 50px auto;
  text-align: center;
  width: 1000px;
}

#tools {
  float: left;
  border-radius: 2px;
  border: 1px solid black;
}

.tool {
  padding: 15px;
}

.tool:not(:last-child) {
  border-bottom: 1px solid black;
}

.tool input {
  width: 50px;
  text-align: center;
}

.tool button {
  padding: 6px 7px;
}

.tool input[type="color"] {
  border: none;
  background: none;
}

.tool .title {
  display: block;
}

.hidden {
  display: none !important;
}

canvas {
  border: 1px solid black;
}