@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;800&family=Noto+Sans+KR:wght@400;700&family=Noto+Sans+JP:wght@400;700&display=swap');

:root {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --card-bg: rgba(255, 255, 255, 0.05);
    --card-border: rgba(255, 255, 255, 0.1);
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    --hover-glow: 0 0 20px rgba(168, 85, 247, 0.4);
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Inter', 'Noto Sans KR', sans-serif;
    line-height: 1.6;
    overflow-x: hidden;
}

/* Lang specific font overrides */
html[lang="ja"] body {
    font-family: 'Inter', 'Noto Sans JP', sans-serif;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 2rem 0;
    margin-bottom: 4rem;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.05em;
}


.lang-switch {
    display: flex;
    align-items: center;
}

.lang-switch a {
    color: #94a3b8;
    text-decoration: none;
    margin-left: 1.5rem;
    font-size: 0.9rem;
    font-weight: 600;
    transition: color 0.3s;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.lang-switch a::before {
    content: '';
    display: block;
    width: 20px;
    height: 15px;
    background-size: cover;
    background-position: center;
    border-radius: 2px;
}

.lang-switch a:first-child::before {
    background-image: url('../flags/kr.svg');
}

.lang-switch a:nth-child(2)::before {
    background-image: url('../flags/us.svg');
}

.lang-switch a:nth-child(3)::before {
    background-image: url('../flags/jp.svg');
}

/* Override with href-based selectors for reliability */
.lang-switch a[href*="/ko/"]::before,
.lang-switch a[href*="ko/"]::before {
    background-image: url('../flags/kr.svg');
}

.lang-switch a[href*="/en/"]::before,
.lang-switch a[href*="en/"]::before {
    background-image: url('../flags/us.svg');
}

.lang-switch a[href*="/ja/"]::before,
.lang-switch a[href*="ja/"]::before {
    background-image: url('../flags/jp.svg');
}

.lang-switch a.active,
.lang-switch a:hover {
    color: #fff;
}

.hero {
    text-align: center;
    margin-bottom: 5rem;
    animation: fadeIn 1s ease-out;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    line-height: 1.2;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: #94a3b8;
    max-width: 700px;
    margin: 0 auto;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    padding-bottom: 4rem;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 20px;
    padding: 2rem;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    justify-content: flex-end;
    height: 300px;
    text-decoration: none;
    color: inherit;
}

.card:hover {
    transform: translateY(-10px);
    border-color: rgba(168, 85, 247, 0.5);
    box-shadow: var(--hover-glow);
}

.card-img-placeholder {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at top right, rgba(255, 255, 255, 0.1), transparent);
    z-index: 0;
    transition: transform 0.4s;
}

.card:hover .card-img-placeholder {
    transform: scale(1.1);
}

.card h2 {
    font-size: 1.8rem;
    z-index: 1;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

.card span {
    z-index: 1;
    color: #94a3b8;
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* Category Specific Background Images */
.card[data-cat="science"] .card-img-placeholder {
    background-image: url('../assets/images/science.jpg');
    background-size: cover;
    background-position: center;
}

.card[data-cat="math"] .card-img-placeholder {
    background-image: url('../assets/images/math.jpg');
    background-size: cover;
    background-position: center;
}

.card[data-cat="philosophy"] .card-img-placeholder {
    background-image: url('../assets/images/philosophy.jpg');
    background-size: cover;
    background-position: center;
}

.card[data-cat="psychology"] .card-img-placeholder {
    background-image: url('../assets/images/psychology.jpg');
    background-size: cover;
    background-position: center;
}

.card[data-cat="history"] .card-img-placeholder {
    background-image: url('../assets/images/history.jpg');
    background-size: cover;
    background-position: center;
}

.card[data-cat="religion"] .card-img-placeholder {
    background-image: url('../assets/images/religion.jpg');
    background-size: cover;
    background-position: center;
}

/* Overlay gradient for text readability */
.card-img-placeholder::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, transparent 0%, rgba(15, 23, 42, 0.8) 100%);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
}


/* Shared Styles from Science Category */
.experiment-area,
#canvas-container {
    width: 100%;
    height: 500px;
    /* Fixed height match */
    background: radial-gradient(circle at center, #1a1a1a, #000);
    border-radius: 20px;
    margin: 2rem 0;
    overflow: hidden;
    border: 1px solid #333;
    position: relative;
    box-shadow: inset 0 0 20px rgba(0, 0, 0, 0.5);
}

.controls {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

/* Unify .btn and .control-btn */
.btn,
.control-btn {
    background: linear-gradient(135deg, #f97316, #dc2626);
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1.2rem;
    font-weight: 700;
    border-radius: 50px;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn:hover,
.control-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 0 20px rgba(255, 100, 50, 0.6);
}

.explanation {
    background: var(--card-bg, rgba(255, 255, 255, 0.05));
    padding: 2rem;
    border-radius: 20px;
    line-height: 1.8;
    font-size: 1.1rem;
    backdrop-filter: blur(10px);
    border: 1px solid var(--card-border, rgba(255, 255, 255, 0.1));
    color: #eee;
    margin: 0 auto 4rem auto;
    max-width: 100%;
    /* Allow full width within container */
}

.explanation h3 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    color: #fff;
    margin-top: 0;
}

.explanation h4 {
    font-size: 1.3rem;
    margin-top: 2rem;
    margin-bottom: 0.5rem;
    color: #e2e8f0;
}

.explanation p {
    color: #cbd5e1;
    line-height: 1.7;
    margin-bottom: 1rem;
}

.highlight {
    color: #f97316;
    font-weight: 700;
}

#status-text {
    text-align: center;
    font-size: 1.2rem;
    margin-top: 1rem;
    margin-bottom: 1.5rem;
    min-height: 2rem;
    color: #fff;
    text-shadow: 0 0 10px #f97316;
}

/* Detail Container used in Science */
.detail-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}