*{
    box-sizing: border-box;
}

body{
    /*background-color: lightblue;*/
}

header{
    width: 90%;
    margin: 20px auto;
    font-size: 4vw;
    text-transform: capitalize;
    border-bottom: 10px double grey ;
}


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

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

li{
    list-style-type: none;
    width: 25%;
    font-size: 1.2vw;
    padding: 1px 10px;
    border-right: 5px solid grey;
}

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


li > img{
    margin: 0px 2px;
}

span{
    color: rgb(113, 191, 218);
}

main{
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

img[alt="principal"]{
    width: 90%;
    margin: 10px auto;
}


h2{
    width: 100%;
    font-size: 1.5vw
}

section{
    display: flex;
    flex-wrap: wrap;
    justify-content: center ;
}

section > img{
    width: 50%;
    border: 1px solid grey;
    margin: 10px 0px;
}

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;
    }


}

@media screen and (min-width: 1000px) {
    section{
        width: 50%;
        margin: 10px 0px;
    }

    main{
        flex-wrap: nowrap;
    }

    img[alt="principal"]{
        width: 100%;
    }

    section > img{
        width: 50%;
        border: 1px solid grey;
        margin: 10px 0px;
    }

    img[alt="twi"],img[alt="mail"]{
        display: inline;
    }


}