CSS valid & invalid textbox validation

CSS valid & invalid textbox validation.txt

input:not(:focus):valid {
  border: 1px solid green;
}
input:not(:focus):valid + span::after {
  content: '✓';
}
input:not(:focus):invalid {
  border: 1px solid red;
}
input:not(:focus):invalid + span::after {
  content: '×';
}