@import url('https://fonts.googleapis.com/css2?family=Roboto+Mono&display=swap');
body {
    margin: 0;
    padding: 0;
    background-color: #fff;
    font-family: 'Roboto Mono', monospace;
}

main {
    text-align: center;
}

.materias {
    display: flex;
}

h3 {
    margin: 0;
    margin-bottom: 20px;
}


.materia {
    margin: 50px;
    padding: 20px 50px;
    max-width: 300px;
    color: #fff;
    text-align: center;
    background-color: rgb(9, 56, 110);
    vertical-align: center;
    border-radius: 20px;
}

a {
    color: #fff;
    text-decoration: none;
    display: inline-block;
    margin-bottom: 20px;
}

@media only screen and (max-width: 600px) {
    .materias {
        display: block;
    }
    img {
        width: 100%;
    }
  }