@charset "utf-8";

    .contents {
            background: #ccc;
            background-image: url(https://thg-hd.com/image/image.jpg);
            background-position: center center;
            background-repeat: no-repeat;
            background-attachment: fixed;
            background-size: cover 
            background-color: #464646;
               }
               
    .parentbox {
            position: relative;
            margin: 0 auto;
            width:800px;
            height: 500px;
            text-align: center
               }
               
    .childbox {
            position: absolute;
            padding: 10px;
            width: 400px;
            height: auto;
            border: solid 5px #fff;
            text-align: center;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%)
               }
               
    h1 {
             display: inline-block;
             text-align: left;
             color: #fff
               }