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

:root {
    --gap: 24px;
    --card-width: min(310px, calc((100vw - 40px - 4 * var(--gap)) / 5));
    --card-height: calc(var(--card-width) * 2.129);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: #f5f1e8;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px 20px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

main {
    width: 100%;
    max-width: 1900px;
}

.site-title {
    font-size: 3rem;
    font-weight: 600;
    text-align: center;
    color: #2d3454;
    margin-bottom: 56px;
    letter-spacing: -0.02em;
}

.cards-container {
    display: flex;
    gap: var(--gap);
    justify-content: center;
    align-items: center;
    flex-wrap: nowrap;
    padding: 20px 0;
}

.card {
    position: relative;
    width: var(--card-width);
    height: var(--card-height);
    flex-shrink: 0;
    perspective: 1000px;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.card:hover {
    transform: translateY(-8px);
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    transition: transform 0.6s cubic-bezier(0.4, 0.2, 0.2, 1);
    border-radius: 24px;
    overflow: hidden;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.1);
}

.card-front {
    transform: rotateY(0deg);
}

.card-front img {
    position: absolute;
    top: -8px;
    left: -8px;
    width: calc(100% + 16px);
    height: calc(100% + 16px);
    object-fit: cover;
    object-position: top;
    display: block;
}

.card-back {
    background: white;
    transform: rotateY(180deg);
    overflow-y: auto;
    scrollbar-width: thin;
    scrollbar-color: rgba(0, 0, 0, 0.2) transparent;
}

.card-back::-webkit-scrollbar {
    width: 6px;
}

.card-back::-webkit-scrollbar-thumb {
    background: rgba(0, 0, 0, 0.2);
    border-radius: 3px;
}

.card-back::-webkit-scrollbar-track {
    background: transparent;
}

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

.card.flipped .card-back {
    transform: rotateY(0deg);
}

.card-content {
    padding: 32px 28px;
    color: #1a1a1a;
}

.card-content h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 6px;
    line-height: 1.2;
    color: #000;
}

.subtitle {
    font-size: 0.9rem;
    color: #666;
    margin-bottom: 24px;
    font-weight: 500;
}

.card-content p {
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 16px;
    color: #333;
}

.card-content p strong {
    color: #000;
    font-weight: 600;
}

.quick-ref {
    margin-top: 24px;
    padding: 16px;
    background: #f8f8f8;
    border-radius: 12px;
    border-left: 3px solid #ddd;
}

.quick-ref p {
    font-size: 0.9rem;
    margin-bottom: 10px;
    line-height: 1.5;
}

.quick-ref p:last-child {
    margin-bottom: 0;
}

/* Responsive: wrap into rows on narrow screens */
@media (max-width: 1100px) {
    :root {
        --card-width: min(280px, calc((100vw - 40px - 2 * var(--gap)) / 3));
    }

    .cards-container {
        flex-wrap: wrap;
    }
}

@media (max-width: 768px) {
    :root {
        --card-width: min(280px, calc((100vw - 40px - var(--gap)) / 2));
    }

    body {
        padding: 20px 10px;
    }

    .site-title {
        font-size: 2rem;
        margin-bottom: 40px;
    }

    .card-content {
        padding: 24px 20px;
    }

    .card-content h2 {
        font-size: 1.3rem;
    }

    .card-content p {
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {
    :root {
        --card-width: min(310px, calc(100vw - 40px));
    }
}

/* Smooth entrance animation */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card {
    animation: fadeInUp 0.6s ease-out backwards;
}

.card:nth-child(1) { animation-delay: 0.1s; }
.card:nth-child(2) { animation-delay: 0.2s; }
.card:nth-child(3) { animation-delay: 0.3s; }
.card:nth-child(4) { animation-delay: 0.4s; }
.card:nth-child(5) { animation-delay: 0.5s; }