.tab-pane button {
    margin: 10px auto;
}

.item-container img {
    max-width: 100%;
}

.puzzle-tab, .puzzle-tab.nav-link {
    background-color: rgba(132, 132, 56, 0.2);
}

.quiz-tab, .quiz-tab.nav-link {
    background-color: rgba(56, 132, 132, 0.2);
}

.city-tab, .city-tab.nav-link {
    background-color: rgba(81, 132, 56, 0.46);
}

.nature-tab, .nature-tab.nav-link {
    background-color: rgba(1, 132, 28, 0.46);
}

.nav-tabs {
    font-size: xx-large;
}

.container .nav-tabs {
    width: 100%;
    border-bottom: 0;
}

.container .nav-tabs>div>a {
    margin-bottom: 0;
    border-radius: 10px 10px 0 0;
}

.nav-tabs a.puzzle-tab.active,
.nav-tabs a.puzzle-tab.active:focus,
.nav-tabs a.puzzle-tab.active:hover,
.nav-tabs a.puzzle-tab:hover {
    background-color: rgba(132, 132, 56, 0.2);
}

.nav-tabs a.quiz-tab.active,
.nav-tabs a.quiz-tab.active:focus,
.nav-tabs a.quiz-tab.active:hover,
.nav-tabs a.quiz-tab:hover {
    background-color: rgba(56, 132, 132, 0.2);
}

.nav-tabs a.city-tab.active,
.nav-tabs a.city-tab.active:focus,
.nav-tabs a.city-tab.active:hover,
.nav-tabs a.city-tab:hover {
    background-color: rgba(81, 132, 56, 0.46);
}

.nav-tabs a.nature-tab.active,
.nav-tabs a.nature-tab.active:focus,
.nav-tabs a.nature-tab.active:hover,
.nav-tabs a.nature-tab:hover {
    background-color: rgba(1, 132, 28, 0.46);
}

.nav-tabs a.active,
.nav-tabs a.active:focus,
.nav-tabs a.active:hover {
    border-bottom-width: 0;
    min-width: 300px;
}

/* The flip card container - set the width and height to whatever you want. We have added the border property to demonstrate that the flip itself goes out of the box on hover (remove perspective if you don't want the 3D effect */
.flip-card {
    background-color: transparent;
    width: 100%;
}

.flip-card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.8s;
    transform-style: preserve-3d;
}

.flip-card:hover .flip-card-inner {
    transform: rotateY(180deg);
}

.flip-card-front, .flip-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden; /* Safari */
    backface-visibility: hidden;
}

.flip-card-back {
    background-color: transparent;
    color: white;
    transform: rotateY(180deg);
    display: flex;
    flex-direction: column;
    justify-content: space-evenly;
    align-items: stretch;
}

.flip-card-back button {
    font-size: 1.2em;
    margin: 0 10px;
}

@media (min-width: 576px) {
    .col-md-6 .flip-card {
        height: 330px;
    }
    .col-sm-3 .flip-card {
        height: 150px;
    }
    .col-sm-4 .flip-card {
        height: 150px;
    }
}

@media (min-width: 768px) {
    .col-md-6 .flip-card {
        height: 450px;
    }
    .col-sm-3 .flip-card {
        height: 240px;
    }
    .col-sm-4 .flip-card {
        height: 240px;
    }
}

.col-md-6 .flip-card {
    height: 540px;
}
.col-sm-3 .flip-card {
    height: 250px;
}
.col-sm-4 .flip-card {
    height: 160px;
}