*{
    box-sizing: border-box;
}

body{
    background-color: antiquewhite;

}
header{
    width: 90%;
    margin: 20px auto;
    font-size: 5vw;
    text-transform: capitalize;
    text-align: left;
    border-bottom: 6px double black;
}
article, footer, main{
    width: 90%;
    margin: 20px auto;

}
footer{
    color: gray
}
ul{
    display: flex;
    flex-wrap: nowrap;

}
li{
    list-style-type: none;
    width: 25%;
    font-size: 1vw;
    padding: 2px 20px;
    border-right: 1px solid black;
    
}
li:last-of-type{
    border: none;
}
article > img{
    margin: 0px 10px;
}
span{
    color: blue;
}

main{
    display: flex;
    flex-wrap: wrap;
}
img[alt="principal"], section{
    width: 90%;
    margin: 10px auto;
 
}
section > img{
    width: 50%;
    border: 1px solid grey;
    margin: 10px 0px;
}
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 0px;
    
} 
img[alt="lec"], img[alt="tw"], img[alt="email"]{
    display: none;

}
@media screen and (min-width: 576px){
    img[alt="lec"]{
        display: inline;
    }
    
    section > img{
        width: 33%;
        border: 1px solid grey;
        margin: 10px 0px;
    }
}
@media screen and (min-width: 1000px){
    img[alt="tw"], img[alt="email"]{
        display: inline;
    }
   section > img{
        width: 50%;
        border: 1px solid grey;
        margin: 10px 0px;
   }
    main{
        justify-content: space-between;
        flex-wrap: nowrap;
    }
    img[alt="principal"]{
        width: 150%;
    }


}