:root {
    --bg-color: #0f172a;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-back: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
    --card-border: rgba(255, 255, 255, 0.1);
    --glass-bg: rgba(15, 23, 42, 0.6);
    --glass-border: rgba(255, 255, 255, 0.05);
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --success: #10b981;
    --header-footer-h: 270px;
    --card-gap: 1rem;
}

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

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow-x: hidden;
    position: relative;
}

/* Background Shapes for modern feel */
.background-shapes {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    overflow: hidden;
}

.shape {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.5;
    animation: float 10s infinite alternate ease-in-out;
}

.shape-1 {
    width: 400px;
    height: 400px;
    background: #3b82f6;
    top: -100px;
    left: -100px;
}

.shape-2 {
    width: 300px;
    height: 300px;
    background: #8b5cf6;
    bottom: -50px;
    right: -50px;
    animation-delay: -5s;
}

.shape-3 {
    width: 250px;
    height: 250px;
    background: #ec4899;
    top: 40%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation-delay: -2s;
}

@keyframes float {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(30px, 50px) scale(1.1); }
}

.container {
    width: 100%;
    max-width: 1000px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
    height: 100vh;
    overflow: hidden;
}

.back-link {
    align-self: flex-start;
    color: white;
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.3) 0%, rgba(139, 92, 246, 0.3) 100%);
    border: 1px solid rgba(59, 130, 246, 0.5);
    backdrop-filter: blur(8px);
    padding: 0.7rem 1.4rem;
    border-radius: 12px;
    text-decoration: none;
    font-weight: 700;
    font-size: 1rem;
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.2), inset 0 1px 1px rgba(255, 255, 255, 0.2);
    margin-bottom: -0.5rem;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

.back-link:hover {
    color: white;
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.5) 0%, rgba(139, 92, 246, 0.5) 100%);
    border-color: rgba(96, 165, 250, 0.8);
    transform: translateX(-5px);
    box-shadow: 0 6px 25px rgba(59, 130, 246, 0.4), 0 0 15px rgba(139, 92, 246, 0.2);
}

header {
    width: 100%;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    padding: 1.5rem 2rem;
    border-radius: 20px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

h1 {
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(to right, #60a5fa, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 2px 10px rgba(96, 165, 250, 0.2);
}

.stats {
    display: flex;
    gap: 1.5rem;
}

.stat-box {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-box .label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    font-weight: 600;
}

.stat-box .value {
    font-size: 1.5rem;
    font-weight: 800;
}

.btn {
    background: var(--card-back);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    font-family: inherit;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.6);
    filter: brightness(1.1);
}

.btn:active {
    transform: translateY(1px);
}

.header-buttons {
    display: flex;
    gap: 1rem;
}

.secondary-btn {
    background: transparent;
    border: 2px solid var(--accent);
    color: var(--accent);
    box-shadow: none;
}

.secondary-btn:hover {
    background: var(--accent);
    color: white;
}

.primary-btn {
    background: var(--success);
    margin-top: 1.5rem;
    font-size: 1.2rem;
    padding: 1rem 2.5rem;
    box-shadow: 0 4px 15px rgba(16, 185, 129, 0.4);
}

.primary-btn:hover {
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.6);
}

.game-board {
    display: grid;
    gap: var(--card-gap);
    perspective: 1000px;
    width: max-content;
    margin: 0 auto;
    justify-content: center;
    align-content: center;
}

.grid-level-1 {
    --cols: 2;
    --rows: 2;
    --max-h: min(calc((100vh - var(--header-footer-h) - var(--card-gap)) / var(--rows)), calc((100vw - 4rem - var(--card-gap)) / var(--cols) / 0.75));
    grid-template-columns: repeat(var(--cols), calc(var(--max-h) * 0.75));
    grid-template-rows: repeat(var(--rows), var(--max-h));
}

.grid-level-2 {
    --cols: 4;
    --rows: 2;
    --max-h: min(calc((100vh - var(--header-footer-h) - var(--card-gap)) / var(--rows)), calc((100vw - 4rem - (var(--cols) - 1) * var(--card-gap)) / var(--cols) / 0.75));
    grid-template-columns: repeat(var(--cols), calc(var(--max-h) * 0.75));
    grid-template-rows: repeat(var(--rows), var(--max-h));
}

.grid-level-3 {
    --cols: 4;
    --rows: 3;
    --max-h: min(calc((100vh - var(--header-footer-h) - (var(--rows) - 1) * var(--card-gap)) / var(--rows)), calc((100vw - 4rem - (var(--cols) - 1) * var(--card-gap)) / var(--cols) / 0.75));
    grid-template-columns: repeat(var(--cols), calc(var(--max-h) * 0.75));
    grid-template-rows: repeat(var(--rows), var(--max-h));
}

.grid-level-4 {
    --cols: 4;
    --rows: 4;
    --max-h: min(calc((100vh - var(--header-footer-h) - (var(--rows) - 1) * var(--card-gap)) / var(--rows)), calc((100vw - 4rem - (var(--cols) - 1) * var(--card-gap)) / var(--cols) / 0.75));
    grid-template-columns: repeat(var(--cols), calc(var(--max-h) * 0.75));
    grid-template-rows: repeat(var(--rows), var(--max-h));
}

.card {
    position: relative;
    width: 100%;
    aspect-ratio: 3/4;
    cursor: pointer;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.card:hover:not(.flipped):not(.matched) {
    transform: scale(1.05) translateY(-5px);
}

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

.card.matched {
    transform: rotateY(180deg) scale(1.05);
    box-shadow: 0 0 20px rgba(16, 185, 129, 0.5);
    z-index: 10;
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 16px;
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
    border: 1px solid var(--card-border);
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

.card-front {
    background: var(--card-bg);
    backdrop-filter: blur(4px);
    transform: rotateY(180deg);
}

.card-front img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.card-back {
    background: var(--card-back);
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.card-back::after {
    content: '?';
    font-size: 3rem;
    color: rgba(255, 255, 255, 0.5);
    font-weight: 800;
}

/* Glassmorphism Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 1;
    transition: opacity 0.3s ease;
}

.modal.hidden {
    opacity: 0;
    pointer-events: none;
}

.modal-content {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    padding: 3rem;
    border-radius: 24px;
    text-align: center;
    transform: scale(1);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    box-shadow: 0 15px 50px rgba(0,0,0,0.5);
}

.modal.hidden .modal-content {
    transform: scale(0.8);
}

.modal h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--success);
}

.modal p {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.time-result {
    font-size: 1.5rem !important;
    color: var(--accent) !important;
    margin-bottom: 2rem !important;
    font-weight: 600;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    :root {
        --header-footer-h: 310px;
        --card-gap: 0.5rem;
    }
    .container {
        padding: 1rem;
        gap: 1rem;
    }
    .grid-level-1 {
        --max-h: min(calc((100vh - var(--header-footer-h) - var(--card-gap)) / var(--rows)), calc((100vw - 2rem - var(--card-gap)) / var(--cols) / 0.75));
    }
    .grid-level-2 {
        --max-h: min(calc((100vh - var(--header-footer-h) - var(--card-gap)) / var(--rows)), calc((100vw - 2rem - (var(--cols) - 1) * var(--card-gap)) / var(--cols) / 0.75));
    }
    .grid-level-3 {
        --max-h: min(calc((100vh - var(--header-footer-h) - (var(--rows) - 1) * var(--card-gap)) / var(--rows)), calc((100vw - 2rem - (var(--cols) - 1) * var(--card-gap)) / var(--cols) / 0.75));
    }
    .grid-level-4 {
        --max-h: min(calc((100vh - var(--header-footer-h) - (var(--rows) - 1) * var(--card-gap)) / var(--rows)), calc((100vw - 2rem - (var(--cols) - 1) * var(--card-gap)) / var(--cols) / 0.75));
    }
    header {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
        border-radius: 16px;
    }
    .header-logo-title {
        flex-direction: column;
        align-items: center;
        text-align: center;
        gap: 0.5rem;
    }
    .game-header-logo {
        height: 40px;
    }
    .stats {
        gap: 1rem;
    }
    .stat-box .value {
        font-size: 1.25rem;
    }
    .header-buttons {
        gap: 0.5rem;
        width: 100%;
        justify-content: center;
    }
    .btn {
        padding: 0.6rem 1.2rem;
        font-size: 0.9rem;
    }
    .sound-btn {
        font-size: 1.1rem !important;
        padding: 0.7rem 1.5rem !important;
    }
    .modal-content {
        padding: 2rem;
    }
    .modal-logo {
        max-width: 140px;
    }
}

/* Header Logo */
.header-logo-title {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.game-header-logo {
    height: 50px;
    width: auto;
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.3));
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.game-header-logo:hover {
    transform: scale(1.08) rotate(-2deg);
}

/* Modal Logo */
.modal-logo {
    max-width: 180px;
    width: 100%;
    height: auto;
    margin-bottom: 0.25rem;
    filter: drop-shadow(0 6px 12px rgba(0, 0, 0, 0.4));
    animation: logoFloat 3s infinite alternate ease-in-out;
}

@keyframes logoFloat {
    0% { transform: translateY(0); }
    100% { transform: translateY(-5px); }
}

/* Game Footer */
.game-footer {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: auto;
    padding-top: 0.5rem;
    opacity: 0.7;
    transition: opacity 0.3s ease;
}

.game-footer:hover {
    opacity: 1;
}

.game-footer .footer-text {
    font-size: 0.75rem;
    color: var(--text-secondary);
    letter-spacing: 1px;
    text-transform: uppercase;
    font-weight: 600;
}

.footer-logo {
    height: 24px;
    width: auto;
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.3));
    transition: transform 0.3s ease;
}

.footer-logo:hover {
    transform: scale(1.05);
}

/* Card Preview Carousel */
.card-carousel {
    width: 100%;
    max-width: 420px;
    overflow: hidden;
    margin: 1.25rem 0;
    padding: 0.5rem 0;
    position: relative;
    mask-image: linear-gradient(to right, transparent, white 20%, white 80%, transparent);
    -webkit-mask-image: linear-gradient(to right, transparent, white 20%, white 80%, transparent);
}

.carousel-track {
    display: flex;
    gap: 0.75rem;
    width: max-content;
    animation: scrollCarousel 18s linear infinite;
}

.carousel-card {
    width: 70px;
    aspect-ratio: 3/4;
    border-radius: 8px;
    border: 1px solid var(--card-border);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
    overflow: hidden;
    background: var(--card-bg);
}

.carousel-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

@keyframes scrollCarousel {
    0% {
        transform: translate3d(0, 0, 0);
    }
    100% {
        transform: translate3d(-50%, 0, 0);
    }
}

/* Full Screen Start Modal styling */
#start-modal {
    background: radial-gradient(circle at center, rgba(15, 23, 42, 0.98) 0%, #0f172a 100%);
    backdrop-filter: none;
}

#start-modal .modal-content {
    background: transparent;
    border: none;
    box-shadow: none;
    width: 100vw;
    height: 100vh;
    border-radius: 0;
    padding: 3rem 2rem;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    max-width: 100%;
    transform: none !important;
    box-sizing: border-box;
}

#start-modal .modal-header {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

#start-modal .modal-logo {
    max-width: 240px;
    width: 100%;
    height: auto;
    margin-bottom: -15px;
}

#start-modal h2 {
    font-size: 2.2rem;
    margin-top: 0;
    margin-bottom: 0;
    background: linear-gradient(to right, #60a5fa, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 2px 10px rgba(96, 165, 250, 0.2);
}

#start-modal .card-carousel {
    max-width: 100%;
    width: 100vw;
    margin: auto 0;
    padding: 1rem 0;
}

#start-modal .carousel-track {
    gap: 2rem;
}

#start-modal .carousel-card {
    width: 280px;
    aspect-ratio: 3/4;
    border-radius: 16px;
    border: 2.5px solid rgba(255, 255, 255, 0.15);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.5);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275), border-color 0.3s ease;
}

#start-modal .carousel-card:hover {
    transform: scale(1.06) rotate(2deg);
    border-color: var(--accent);
}

/* Sound Button Prominence */
.sound-btn {
    font-size: 1.35rem !important;
    padding: 0.9rem 2.2rem !important;
    background: rgba(59, 130, 246, 0.15) !important;
    border-color: var(--accent) !important;
    color: var(--text-primary) !important;
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
}

.sound-btn:hover {
    background: var(--accent) !important;
    color: white !important;
    box-shadow: 0 0 15px rgba(59, 130, 246, 0.4) !important;
}