*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
*::before{
    box-sizing: border-box;
}
*::after{
    box-sizing: border-box;
}

body{
    height: 100vh;
    background: #b8b8b8 url('http://img01.taopic.com/170219/267846-1F21913300390.jpg') center center no-repeat;
    background-size: 100%;
    display:flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    position: relative;
}

header{
    line-height: 100px;
    padding: 0 140px;
    font-size: 30px;
    height: 100px;
    min-width: 850px;
    position: absolute;
    top: 100px;
    left: 50%;
    margin-left: -425px;
}

main{
    text-align: center;
    min-width: 850px;
}
#mainX{
    display: inline-block;
}
#mainX > div:nth-child(2){
    margin-left: 4px;
}
#mainX > div:nth-child(3){
    margin-left: -54px;
}
#mainX>div{
}
kbd{
    border: 1px solid;
    border-radius: 5px;
    width: 64px;
    height: 64px;
    margin: 5px;
    display: inline-block;
    text-transform: uppercase;
    position: relative;
    background-color: #b8b8b8;
    font-size: 20px;
    line-height: 40px;
}
kbd .divButton{
    position: absolute;
    bottom: 0;
    right: 0;
}
kbd button{
    background: orange;
    color: white;
    display: none;
    border: none;
    margin-left: 5px;
    padding: 1px 2px;
    border-radius: 50%;
}
kbd:hover button{
    display: inline-block;
}