index.css

@import url('https://fonts.googleapis.com/css2?family=Space+Mono&display=swap');

* {
  margin: 0;
  padding: 0;

  font-size: 16px;
  font-family: 'Space Mono', monospace;

  overflow: hidden;
  user-select: none;
}

body {
  width: 100vw;
  height: 100vh;

  display: flex;
  flex-direction: column;
  justify-content: space-evenly;

  background-color: rgb(30, 25, 44);
}
body > div {
  background-color: #6664;
}

#status {
  display: flex;
}

#status > span {
  flex: 1;

  color: #ddd;
  font-size: 1.5em;
  text-align: center;
  text-shadow: 0.3vmin 0.3vmin 0 #000;
}
#status > span:not(:last-child) {
  border-right: 1vmin solid rgb(30, 25, 44);
}
#status > span > span {
  display: flex;
  flex-direction: column;
  justify-content: center;

  font-size: 2em;
}
#branch-count {
  color: rgb(218, 106, 54);
}
#tile-count {
  color: rgb(81, 218, 54);
}
#tick-rate {
  color: rgb(27, 146, 201);
}

#canvas-container {
  --padding: 2.5%;
  --sizeBorder: 0.2vmin solid #fff2;

  position: relative;
  padding: var(--padding);

  height: 70%;

  box-sizing: border-box;
}
#canvas-container::before {
  position: absolute;
  top: var(--padding);
  right: var(--padding);

  width: calc(100% - var(--padding) * 3);
  text-align: center;

  border-bottom: var(--sizeBorder);
  border-left: var(--sizeBorder);
  border-right: var(--sizeBorder);

  content: attr(w) " Tiles";
  color: #ccc;
}
#canvas-container::after {
  position: absolute;
  bottom: var(--padding);
  left: var(--padding);

  height: calc(100% - var(--padding) * 4);
  text-align: center;

  border-bottom: var(--sizeBorder);
  border-top: var(--sizeBorder);
  border-right: var(--sizeBorder);

  content: attr(h) " Tiles";
  color: #ccc;
  writing-mode: vertical-lr;
  text-orientation: mixed;
}
#canvas {
  position: absolute;
  top: calc(var(--padding) * 3);
  right: var(--padding);

  border: 0.05vmin solid #6665;
}

#info {
  padding: 0.4% 0;

  color: #aaa;
  text-align: center;
}