<input type="email" placeholder="email@address.com">

input:not(:focus-visible):invalid {
  text-decoration: underline wavy red;
}

input {
  padding-block: .5ch;
  padding-inline: 1ch;
  line-height: 1.5;
}

* {
  box-sizing: border-box;
  margin: 0;
}

html {
  block-size: 100%;
  color-scheme: dark light;
}

body {
  min-block-size: 100%;
  font-family: system-ui, sans-serif;
  
  display: grid;
  place-content: center;
}