*{
    box-sizing: border-box;

}
body{
    background-color: white;

}
header{
    width: 90%;
    margin: 20px auto;
    font-size: 4vw;
    text-align: left;
    text-transform: capitalize;
    border-bottom: 8px double black ;
}
article, footer,main{
    width: 90%;
    margin: 20px auto;
}

footer{
    color: grey;
}
ul{
    display: flex;
    flex-wrap: nowrap;
}
li{
    list-style-type: none;
    width: 22%;
    font-size: 1.2vw;
    border-right: 2px solid black;
    padding: 1px 10px;
}
li:last-of-type{
    border: none;
}
li > img{
    margin:0px 1px;
}
span{
    color: blue;
}
img[alt="principal"],section{
    width: 90%;
    
}
main{
    display: flex;
    flex-wrap: wrap;
    justify-content: center ;
}
h2{
    width: 100%;
    font-size: 2vw;
}
section{
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
}

img[alt="stu"],img[alt="twi"],img[alt="mail"]{
    display: none;
}
@media screen and (min-width: 576px){
    img[alt="stu"],img[alt="twi"]{
        display: inline;
    }

    section{
        justify-content: center;
    }
    section > img{
    width: 33%;
    border: 1px solid grey;
    margin: 15px 0px;
}
}
@media screen and (min-width: 1000px){
    img[alt="mail"]{
        display: inline;
    }
    main{
        
        flex-wrap: nowrap;
    }
    section > img{
    width: 45%;
    border: 1px solid grey;
    margin: 15px 0px;
    
}
img[alt="principal"]{
    margin: 10px;
}
}