@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Serif:wght@200&display=swap'); 

*{ padding: 0; margin: 0; box-sizing: border-box; transition: 1s all; }


header { 
    color: #ffffff; 
    background-image: url(../img/portada.jpg); 
    padding: 1rem;
    text-align: center;
    background-repeat: no-repeat;
    background-size: cover;
    width: auto;
    background-position: center;
}

img {
    border-radius: 6rem;
}

h1 {
    color: #ffffff; 
    margin-top: 15;
    font-family: 'IBM Plex Serif', serif;
    font-weight: 900;
}

h2 {
    font-family: 'IBM Plex Serif', serif; 
    color: white
}

nav { 
    color: #ffffff; 
    background:rgba(0, 0, 0, 0.84); 
    padding: 1rem;
    text-align: center;
}

nav ul li { 
    display: inline-block; 
}

nav ul li a { 
    color: #ffffff; 
    text-decoration: none; 
    margin: 8rem; 
}

a:hover {
    box-shadow: 0.2rem 0.2rem 0.2rem #ff0000; 
    padding: 1%; 

}

main section { 
    background: #000000;
    text-align: center;
}

main section article { 
    color: #ffffff; 
    background: #565a5f; 
    padding: 1rem; 
    margin-left: 0,5rem; 
    text-decoration: none; 
}

.color-article {
    background: #000000;
}

.color-article2 {
    text-align: center;
}

main section article h3 a { 
    color: #ffffff; 
    text-decoration: none; 
}

main section article ul { 
    font-family: 'Montserrat', sans-serif;
}

main section article ul p {
    padding: 2px;
}

.compañeros{ 
    padding: 2rem;
    border-radius: 20rem;
    max-width: 90%;
}

.nombre{
    font-family: 'IBM Plex Serif', serif;
    font-size: 1rem;
    font-weight: bold;

}

.alumnos {
    width: 100%;
    display: flex;
    flex-direction: row;
	flex-wrap: nowrap;
	justify-content: center;
	align-items: center;
	align-content: center;
   
}

.alumnos a {
        font-family: 'IBM Plex Serif', serif;
        text-decoration: none;
        color: #666666;
}
section-fotos{
    padding-top: 1rem;
}

.fotos { 
    background: #000000; 
    padding: 0 3rem 2rem; 
    width: 100%; 
    display:flex; 
    justify-content: space-between; 
    flex-flow: wrap; 
    align-self: center;
}
 
.cuadro { 
    width: 20%; 
    padding: auto; 
    display: flex; 
    flex-flow: column; 
}

.cuadro .foto {
    width: 6.25rem; 
    height: 6.25rem;
}
    
.contenido { 
    color: #fff;
    font-family: 'IBM Plex Serif', serif;
    font-weight: 400; 
    font-size: 1rem; 
    text-decoration: none; 
    padding: 0.5rem; 
    display: inline-block; 
    text-align: center;
}


.foto { 
    width:5rem; 
    height:5rem; 
    border-radius:10px;  
    align-self: center;
}

footer { 
    color: #ffffff; 
    background: #000000;
    border-top: 0.1rem solid #ffffff;
    padding: 1rem; 
    font-size: 0.8rem; 
}

<!-- comentario -->