source/src/styles.css

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body,
#root {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

body {
  font-family:
    ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Monaco, Consolas,
    monospace;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* no focus ring flash on the click targets, but keep it for keyboard users */
button {
  font-family: inherit;
  cursor: pointer;
}
button:focus:not(:focus-visible) {
  outline: none;
}