.hero-image {
    background-image: linear-gradient(rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.5)), url("../png/banner_teacher.jpg");
    height: 100vh;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    position: relative;
}

.hero-text {
    text-align: center;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
}

.card {
    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2);
    transition: 0.3s;
    margin-bottom: 50px;
}

.card:hover {
    box-shadow: 0 8px 16px 0 rgba(0, 0, 0, 0.2);
}
.cardcontainer {
    padding: 20px 16px;
}
.cardgroup {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-column-gap: 20px;
    grid-row-gap: 1em;
}

@media only screen and (max-width: 768px) {
    .cardgroup {
        grid-template-columns: repeat(1, 1fr);
    }
    /* .card {
        margin: 40px;
    } */
}