@import url('https://fonts.googleapis.com/css2?family=Luckiest+Guy&display=swap');

html {
    --primary-color: rgb(130, 229, 251);
    --secondary-color: rgb(27, 124, 165);
}

html,
body {
    margin: 0;
}

body {
    font-size: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 1em;
    padding-bottom: 1em;
    background-color: var(--secondary-color);
    color: var(--primary-color);
    font-family: "Luckiest Guy", cursive;
    letter-spacing: 0.15em;
}

.heading {
    font-size: 2em;
}

.description {
    font-size: 1.5em;
}

#game-board {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1em;
    margin-top: 1em;
}

#new-game-button {
    border: none;
    border-radius: 1.5em;
    padding: 0.5em 1.5em;
    background-color: var(--primary-color);
    color: white;
    font-size: 1em;
    font-family: inherit;
    letter-spacing: inherit;
    text-transform: uppercase;
    cursor: pointer;
}

#new-game-button:hover {
    opacity: 0.8;
}

.card {
    width: 5em;
    height: 5em;
    perspective: 50em;
    cursor: pointer;
}

.card-inner {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.5s;
}

.card-front,
.card-back {
    width: 100%;
    height: 100%;
    position: absolute;
    backface-visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: var(--primary-color);
    border-radius: 0.5em;
    font-size: 2.5em;
    color: white;
    box-shadow: 0.02em 0.02em 0.02em 0.02em rgba(0, 0, 0, 0.1);
}

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

.card-back {
    transform: rotateY(180deg);
}