pre code{
    line-height: 25px;
    border-radius: 4px;
    font-family: "SourceHanSans-Regular",Monaco,Menlo,Consolas,"Courier New",monospace;
    font-size: 14px;
}
pre .copytextarea{
    width: 1px;
    height: 1px;
    line-height: 1px;
    overflow: hidden;
}
pre {
    position: relative; 
}
pre .copybtn{ 
    display: none;
    position: absolute;
    top:2px;
    right: 2px;
    background: #333;
    color: #9c9c9c;
    border: 0px solid #232323;
}
pre .copybtn:hover{ 
    color: #fff;
    cursor: pointer;
}
pre:hover .copybtn{
    display: block;
}