style.css

/* Fonts */
@import url('https://fonts.googleapis.com/css2?family=Acme&family=Press+Start+2P&display=swap');

/* If newer grid 'gap' property is not supported, ensure backup for grid is applied */

@supports (gap: 1.5rem) {
    .game-area {
        margin: 1.5rem;
    }
}

/* General reset */

* {
    margin: 0;
    padding: 0;
}

/* Set background / general styles */

body {
    background-image: url('./media/bg.jpg');
    color: #C34134;
    font-family: 'Acme', sans-serif;
    font-weight: 800;
    letter-spacing: 2px;
}

/* Nav holds the heading and game control buttons
Adding 'right' property to nav reconciles incompatibility between 'fixed' & 'flex' */

nav {
    border-bottom: 2px solid #74A674;
    display: flex;
    align-items: center;
    justify-content: space-between;
    opacity: 0.9;
    padding: 0 2.5rem;
    position: fixed;
    left: 0;
    right: 0;
    top: 0;
    z-index: 1000;
}

nav,
table {
    background-color: #000;
}

/* Brand image & alien icon SVGs courtesy of flaticon.io */

.brand {
    padding: 10px 0;
    width: 80px;
}

.brand,
.win-badge-image,
.medal-title,
.medal-image {
    height: auto;
}

h1 {
    font-size: 4rem;
}

h1,
#msg-display {
    color: #74A674;
}

/* Area that displays messages to players during game & end of game */

.ui {
    margin-top: 8%;
}

.ui,
table {
    text-align: center;
}

/* Game control buttons */

button {
    border: none;
    border-radius: 22px;
    color: #000;
    cursor: pointer;
    margin: 1rem;
    padding: 10px 20px 10px 20px;
}

button,
caption,
#msg-display {
    font-size: 1.2rem;
}

button:active {
    box-shadow: inset 1px 1px 6px #FFF;
}

.flip-btn {
    background: #3DC72E;
}

.flip-btn:hover {
    background: #3CE853;
}

.reset-game-btn {
    background: #007DE4;
}

.reset-game-btn:hover {
    background: #009AFF;
}

.reset-wins-btn {
    background: #D93434;
}

.reset-wins-btn:hover {
    background: #FF1919;
}

/* Scoreboard section */

caption {
    margin: 30px;
}

table,
th,
td {
    border: 3px solid #545454;
    border-collapse: collapse;
    color: #FFF;
    font-family: 'Press Start 2P', cursive;
    font-size: 0.7rem;
    padding: 1rem;
}

table,
.medal-image {
    margin: auto;
}

/* Game grid containing all images / cards */

.game-area {
    display: grid;
    grid-template-rows: repeat(4, 1fr);
    grid-template-columns: repeat(5, 1fr);
    gap: 1rem;
    margin-top: 5%;
}

.card img {
    height: 100%;
    width: 100%;
}

/* Win badge that displays for the winner at the end of the game & medals that are acquired when enough games are won (initially hidden) */

.win-badge-image,
.medal-title,
.medal-image {
    width: 70px;
}

.medal-title {
    width: 30px;
}

/* Set general properties of each individual card */

.game-area div {
    background-color: #74A674;
    border-radius: 10%;
    height: 250px;
    width: 230px;
}

/* Sections that contain cards in divs */

.container {
    height: 300px;
    position: relative;
    width: 200px;
    -webkit-perspective: 1000px;
    -moz-perspective: 1000px;
    -o-perspective: 1000px;
    perspective: 1000px;
}

/* Individual card styling */

.card,
.card div {
    height: 100%;
    position: absolute;
    width: 100%;
}

.card {
    transform-style: preserve-3d;
    transition: transform 1s;
    -webkit-transform-origin: 50% 50%;
}

/* 'Transform' and 'rotate' had a 98% compatibilty rating, so some webkits omitted */

.card div {
    display: block;
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    -o-backface-visibility: hidden;
    backface-visibility: hidden;
}

/* Back of each card & class applied with JS in order to turn card over when clicked */

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

/* Animations: removing cards when pair is found */

@keyframes slide-left {
    100% {
        margin-left: -5000px;
    }
}

@keyframes slide-up {
    100% {
        margin-top: -5000px;
    }
}

/* Hide the divs that show a win animation - unnecessary until game over */

.span-container,
.medal-image {
    display: none;
}

/* General styling & spacing between elements */

#msg-display,
#pvp-display {
    padding: 20px;
}

#pvp-display,
#winner-title,
#winner-name {
    font-size: 2.5rem;
}

/* Animation showing who plays who, which runs after users have entered their names */

@keyframes matchup {
    0% {
        font-size: 0;
        opacity: 0;
    }

    50% {
        font-size: 3rem;
        text-shadow: 2px 2px 12px #74A674;
    }
}

/* Animations for winner name displayed at the end of the game */

#winner-title {
    animation: train 1.8s ease forwards;
    margin-right: 1rem;
}

#winner-name {
    animation: plane 2.8s ease forwards;
    position: absolute;
}

/* First half of text slides in from left, 'train' */

@keyframes train {
    0% {
        margin-left: -2000px;
    }

    100% {
        margin-left: inherit;
    }
}

/* Second half of text drops in from top, 'plane' */

@keyframes plane {
    0% {
        margin-top: -2000px;
    }

    100% {
        margin-top: inherit;
    }
}