.activity-image-size a img {
    width: 300px;
    height: 375px;
    border-radius: 10px;
}

.groups-image-size a img {
    width: 300px;
    height: 375px;
    border-radius: 10px;
}

.members-image-size a img {
    width: 300px;
    height: 375px;
    border-radius: 10px;
}

.forums-image-size a img {
    width: 100%;
    height: 100px;
}