*{
    box-sizing: border-box;
}

body{
    background-color: rgb(255, 255, 255);
}

header{
    width: 90%;
    margin: 20px auto;
    font-size: 3vw;
    color: rgb(122, 122, 122);
    border-bottom: 10px double rgb(122, 122, 122);
}

article, footer, main{
    width: 90%;
    margin: 20px auto;
}

footer{
    color: grey;
}

ul{
    display: flex;
    flex-wrap: nowrap;
}

li{
    list-style-type: none;
    width: 20%;
    font-size: 1.5vw;
    padding: 1px 10px;
    border-right: 2px solid rgb(122, 122, 122);
}

li:last-of-type{
    border: none;
}

li > img{
    margin: 0 1px;

}

span{
    color: rgb(36, 50, 255);
}

img[alt="principal"]{
    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;
}

section > img{
    width: 50%;
    border: 1px solid grey;
    margin: 10px 0;
}
img[alt="stu"],img[alt="twi"],img[alt="mail"]{
    display: none;
}

@media screen and (min-width: 576px){
    img[alt="stu"]{
    display: inline;
    }

    section{
        justify-content: center;
    }
    section > img{
        width: 33%;
        border: 1px solid grey;
        margin: 10px 0px;
    }
}

@media screen and (min-width: 1000px){
    img[alt="twi"], img[alt="mail"]{
    display: inline;
    }
    main{
        flex-wrap: nowrap;
    }
    main > img{
        width: 170%;
        margin: auto 10px;
    }
    section > img{
        width: 50%;
    }
}