body {

    padding: 30px;

}

.g-father {

    width: 100px;

    margin: 20px auto;

    padding: 30px;

    border:1px solid #999;

}

​

input {

    display: block;

    border: none;

    outline: none;

    background: none;

    border: 1px solid #333;

    cursor: pointer;

    margin: 0 auto;

    &:focus {

        background: #00bcd4;

    }

}

​

body:focus-within {

    background: blue;

}

​

.g-father:focus-within {

    background: red;

}