:root {
  color-scheme: light;
  --surface: #fff;
  --focus: #737373;
  --target: 48px;
  --space: 24px;
}

html,
body {
  width: 100%;
  height: 100%;
  min-height: 100svh;
  margin: 0;
  background: var(--surface);
}

body {
  overflow: hidden;
}

.a {
  position: fixed;
  right: calc(var(--space) + env(safe-area-inset-right, 0px));
  bottom: calc(var(--space) + env(safe-area-inset-bottom, 0px));
  width: var(--target);
  height: var(--target);
  margin: 0;
}

.b {
  display: block;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
  appearance: none;
  -webkit-appearance: none;
  background: transparent;
  border: 0;
  border-radius: 0;
  box-shadow: none;
  cursor: default;
  -webkit-tap-highlight-color: transparent;
}

.b:focus {
  outline: none;
}

.b:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 4px;
}