html {
  display: flex;
  height: 100%;
}

:root {
  --background: #eee;
  --color: #222;
  --layout: row;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #222;
    --color: #eee;
  }
}

body.dark {
  --background: #222;
  --color: #eee;
}

body {
  background: var(--background);
  color: var(--color);
  display: flex;
  flex: 1;
  flex-direction: column;
  font: icon;
  transition: background .1s, color .1s;
}

h1 {
  align-items: center;
  display: flex;
  gap: 1ex;
}

#arrowSpan span {
  display: none;
}

#arrowSpan::after {
  display: inline-block;
}

body.horizontal #arrowSpan::after {
  content: '→';
}

body.vertical #arrowSpan::after {
  content: '↓';
}

a {
  color: inherit;
}

button {
  background: var(--background);
  border: 1px solid var(--color);
  border-radius: 2px;
  color: var(--color);
  cursor: pointer;
  height: 100%;
  padding: 1ex 1em;
  transition: background .1s, color .1s;
}

#mainDiv {
  display: flex;
  flex: 1;
  gap: 1ex;
}

body.horizontal #mainDiv {
  flex-direction: row;
}

body.horizontal #arrowSpan::after {
  align-items: center;
  display: flex;
  height: 100%;
}

body.vertical #mainDiv {
  flex-direction: column;
}

body.vertical #arrowSpan::after {
  display: flex;
  justify-content: center;
  width: 100%;
}

textarea {
  background: var(--background);
  border: 1px solid var(--color);
  border-radius: 2px;
  color: var(--color);
  flex: 1;
  transition: background .1s, color .1s;
}

textarea:read-only {
  opacity: .75;
}