style.css

body {
  --text: hsl(0 0% 15%);
  font-family: sans-serif;
  background-color: hsl(0 0% 96%);
  color: var(--text);
}
body.dark-theme {
  --text: hsl(0 0% 90%);
  background-color: hsl(223 39% 7%);
}

main {
  display: flex;
  flex-direction: column;
  align-items: center;
  max-width: 80rem;
  text-align: center;
}

a {
  color: var(--text);
}

select, input, button, .text-gen-output {
  padding: 0.5rem 1rem;
}

select, img, input {
  margin: 0.5rem auto 1rem;
}

form {
  width: 25rem;
  margin: 0 auto;
}

input {
  width: 70%;
}

.text-gen-output {
  min-height: 1rem;
  margin: 0;
  align-self: start;
  border: 2px solid var(--text);
}