html,
body{
    height: 100%;
}

.wrapper{
    box-sizing: border-box;
    border: 10px solid #000;
    background-image: url(https://kakechimaru.com/wp-content/uploads/2021/11/211120_03.jpg);
    background-size: cover;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    position: relative;
}
.wrapper::before{
    content: ".wrapper要素";
    color: #000;
    font-size: 14px;
    font-weight: bold;
    position: absolute;
    top: 10px;
    left: 10px;
}

.inner{
    transform: skew(10deg);

    border: 10px solid #646464;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 70%;
    height: 70%;
    position: relative;
}
.inner::before{
    content: ".inner要素";
    color: #646464;
    font-size: 14px;
    font-weight: bold;
    position: absolute;
    top: 10px;
    left: 10px;
}

.box{
    mix-blend-mode: multiply;

    background-color: blue;
    padding-top: 45%;
    width: 45%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}
.box::before{
    content: ".box要素";
    color: #fff;
    font-size: 14px;
    font-weight: bold;
    position: absolute;
    top: 10px;
    left: 10px;
}