* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
html {
  color: #333;
  font-family: arial ,"Open Sans", sans-serif;
  background:linear-gradient(45deg, rgba(0, 0, 0, 0.8), rgba(0, 0, 0, 0.8)),url(http://tohoanbac.rf.gd/set3.jpg) no-repeat fixed;
  background-size: cover;
  
}



#box {
    margin :0 auto;
    width:1200px;
    height:500px;
}

#leftbox {
    width: 1200px;
}
    #leftbox h1 {
        padding: 100px;
        padding-bottom: 0px;
        color: #000;
        text-align: center;
    }
    #leftbox p {
        padding: 100px;
        padding-top: 0px;
        padding-bottom: 0px;
        color: #000;
        text-align: center;
    }

    #leftbox h2 {
        padding: 100px;
        padding-top: 0px;
        color: #000;
        text-align:center;
    }