:root {
    --neon-gold: #2a2dee;
    --neon-purple: #20a4e6;
    --dark-bg: #000000;      /* Dark purple background */
    --light-bg: #00aeff;     /* Lighter purple for containers */
    --text-color: #EAEAEA;
    --matched-glow: #0008ff; /* Contrasting teal for matched glow */
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--dark-bg);
    color: var(--text-color);
    font-family: var(--font-family);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    padding: 10px;
}

.header {
    width: 100%;
    text-align: center;
    padding: 10px;
    margin-bottom: 15px;
    font-size: 1.1em;
    color: var(--neon-gold);
    text-shadow: 0 0 5px var(--neon-gold), 0 0 10px var(--neon-gold);
}

.game-container {
    max-width: 600px;
    width: 100%;
    text-align: center;
}

.game-title {
    margin-bottom: 10px;
    font-size: 2.8em;
    font-weight: bold;
    color: var(--neon-purple);
    text-shadow: 0 0 10px var(--neon-purple), 0 0 20px var(--neon-purple);
}

.level-display {
    font-size: 1.5em;
    color: #fff;
    margin-bottom: 15px;
}

.stats-container {
    display: flex;
    justify-content: space-around;
    font-size: 1.3em;
    margin-bottom: 15px;
    background: var(--light-bg);
    padding: 10px;
    border-radius: 10px;
    border: 1px solid var(--neon-gold);
}

.memory-game {
    width: 100%;
    display: grid;
    gap: 8px;
    perspective: 1000px;
}

.memory-card {
    background-color: transparent;
    aspect-ratio: 1 / 1;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    cursor: pointer;
}

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

.front-face, .back-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 8px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.8em;
    border: 2px solid var(--neon-purple);
    overflow: hidden;
}

.front-face {
    background: var(--light-bg);
    transform: rotateY(180deg);
    color: var(--text-color);
}

.back-face {
    background: linear-gradient(135deg, var(--neon-gold), var(--neon-purple));
    font-size: 2.2em;
    color: var(--dark-bg);
    box-shadow: 0 0 10px var(--neon-purple);
}

.memory-card.matched {
    cursor: default; /* Make it unclickable */
}

/* New style for matched cards */
.memory-card.matched .front-face {
    box-shadow: 0 0 20px var(--matched-glow), inset 0 0 10px var(--matched-glow);
    border-color: var(--matched-glow);
    color: var(--matched-glow);
}

#restart-game-button {
    margin-top: 20px;
    padding: 12px 25px;
    font-size: 1.1em;
    font-weight: bold;
    color: #fff;
    background-color: var(--neon-purple);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

#restart-game-button:hover {
    box-shadow: 0 0 20px var(--neon-purple);
}

.popup-container {
    display: none;
    position: fixed; top: 0; left: 0;
    width: 100%; height: 100%;
    background-color: rgba(0, 0, 0, 0.9);
    justify-content: center; align-items: center;
    z-index: 100;
}

.popup-container.show { display: flex; }

.popup-box {
    background: var(--light-bg);
    padding: 30px;
    border-radius: 20px;
    text-align: center;
    border: 2px solid var(--neon-gold);
    box-shadow: 0 0 30px var(--neon-gold);
}

.popup-box h2 {
    color: var(--matched-glow);
    text-shadow: 0 0 15px var(--matched-glow);
}

#next-button {
    background-color: var(--neon-gold);
    color: var(--dark-bg);
}