.app-margin-top{
    margin-top: 40px;
}
.app-margin-bottom{
    margin-bottom: 40px;
}
.app-padding-top{
    padding-top: 60px;
}

.img-size{
    width: 300px;
    height: auto;
}
.img-size2{
    width: 500px;
    height: auto;
}
.img-centered{
    margin: 0 auto;
}