* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    transition: all 0.3s ease;
}

body {
    font-family: 'Poppins', sans-serif;
    min-height: 100vh;

    background: #333;
    color: #fff;
}

a {
    text-decoration: none;
}

ul {
    list-style: none;
}

header {
    position: fixed;
    width: 100%;
    height: 4em;
    display: flex;
    justify-content: space-around;
    align-items: center;
    border-bottom: 2px solid #fff;
}

header ul {
    display: flex;
}

main {
    padding: 6em;
    padding-top: 4em;
    padding-bottom: 0;
    display: flex;
    flex-direction: column;
}

main h1 {
    padding-bottom: 1em;
}

main section {
    display: flex;
    flex-wrap: wrap;
    gap: 2em;
}

main section article {
    flex: 1 1 300px;
    background: rgba(0, 0, 0, 0.3);
    padding: 1em;
    padding-top: 0.5em;
    border-radius: 1em;
}

main section article h2 {
    margin-bottom: 0.5em;
    font-weight: 300;
    color: #c6c6c6;
    font-size: 1.25em;
}

main section article .display {
    width: 100%;
    height: 175px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 0.5em;
    display: grid;
    place-items: center;
}

main section article .display .card {
    position: absolute;
    width: 150px;
    height: 100px;
    background: #fff;
    border-radius: 0.5em;
    display: grid;
    place-items: center;
    color: #333;
    font-weight: 600;
    font-size: 2em;
}

main section article .display .card .box {
    width: 50px;
    height: 50px;
    background: rgb(38, 98, 235);
    border-radius: 0.25em;
}

#perspective .display {
    perspective: 500px;
}

#perspective .display:hover .card {
    transform: rotateX(45deg);
}

#perspective-origin .display {
    perspective: 500px;
    perspective-origin: bottom left;
}

#perspective-origin .display .card {
    background-image: conic-gradient(from 90deg at 50% 50%, #fff, #ccc, #fff);
}

#perspective-origin .display:hover .card {
    transform: rotateY(45deg);
}

#transform-origin .display:hover .card .box {
    transform: rotate(45deg);
    transform-origin: 0 0;
}

#transform-style .display {
    perspective: 500px;
    transform-style: preserve-3d;
}

#transform-style .display:hover .card {
    transform: rotateX(30deg) rotateY(-30deg);
}

#transform-style .display:hover .card:first-child {
    transform: rotateX(30deg) rotateY(-30deg) translateZ(1em);
    background: rgb(38, 98, 235);
}

#transform-style .display:hover .card:last-child {
    transform: rotateX(30deg) rotateY(-30deg) translateZ(-1em);
    background: rgb(235, 38, 38);
}

#backface-visibility .display {
    perspective: 500px;
}

#backface-visibility .display .card {
    backface-visibility: hidden;
}

#backface-visibility .display .card:first-child {
    background: rgb(38, 98, 235);
}

#backface-visibility .display .card:last-child {
    background: rgb(235, 38, 38);
    transform: rotateY(180deg);
}

#backface-visibility .display:hover .card:first-child {
    transform: rotateY(180deg);
}

#backface-visibility .display:hover .card:last-child {
    transform: rotateY(360deg);
}

#transform-box .display {
    perspective: 500px;
}

#transform-box .display:hover .card .box {
    transform: rotateX(30deg) rotateY(-30deg);
}