#content {
    display: flex;
    flex-direction: row-reverse;
}
#main {
    flex: 1;
    float: left
}
#menu {
    width: 200px;
    float: left;
}

#gallery img{
    width: 32%;
}
h1 {
    color: blue;
    background-color: lightgray;
}
.menu_item {
    font-weight: bold;
}