Example节

by booktu8

HTML

<!-- Learn about this code on MDN: https://developer.mozilla.org/zh-CN/docs/Web/CSS/:invalid -->

<form>
  <label for="url_input">Enter a URL:</label>
  <input type="url" id="url_input" />
  <br />
  <br />
  <label for="email_input">Enter an email address:</label>
  <input type="email" id="email_input" required/>
</form>

CSS

input:invalid {
  background-color: #000;
}

form:invalid {
  border: 5px solid #000;
}

input:valid {
  background-color: #red;
}

form:valid {
  border: 5px solid #red;
}
  
input:required {
  border-color: #800000;
  border-width: 3px;
}

input:required:invalid {
  border-color: #C00000;
}