:root {
    --bg-dark: #0a0a0f;
    --bg-panel: #12121a;
    --text-primary: #ffffff;
    --text-secondary: #94a3b8;
    --text-tertiary: #cbd5e1;
    --accent-blue: #3b82f6;
    --accent-purple: #8b5cf6;
    --glass-bg: rgba(255, 255, 255, 0.03);
    --glass-border: rgba(255, 255, 255, 0.08);
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --font-display: 'Outfit', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', ui-monospace, monospace;

    /* Okabe-Ito palette used in the paper */
    --moral-selfish:    #E69F00;
    --moral-kin:        #D55E00;
    --moral-reciprocal: #56B4E9;
    --moral-universal:  #0072B2;
}

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

body {
    background-color: var(--bg-dark);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    overflow-x: hidden;
}

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    padding: 0.1em 0.4em;
    background: rgba(255,255,255,0.06);
    border-radius: 4px;
    color: #e2e8f0;
}

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

/* Typography */
h1, h2, h3 { font-family: var(--font-display); line-height: 1.2; }

.gradient-text {
    background: linear-gradient(to right, #60a5fa, #c084fc, #f472b6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-title {
    font-size: clamp(2rem, 3.5vw, 2.75rem);
    margin-bottom: 1rem;
    text-align: center;
    font-weight: 800;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    font-size: 1.1rem;
    max-width: 780px;
    margin-left: auto;
    margin-right: auto;
}

.section { padding: 6rem 0; }

/* ---------- Hero ---------- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    padding: 4rem 2rem;
}

.blob {
    position: absolute;
    filter: blur(80px);
    z-index: -1;
    opacity: 0.6;
    border-radius: 50%;
    animation: float 20s infinite ease-in-out alternate;
}

.blob-1 { width: 400px; height: 400px; background: rgba(59, 130, 246, 0.3); top: -10%; left: -10%; }
.blob-2 { width: 500px; height: 500px; background: rgba(139, 92, 246, 0.2); bottom: -20%; right: -10%; animation-delay: -5s; }
.blob-3 { width: 300px; height: 300px; background: rgba(236, 72, 153, 0.2); top: 40%; left: 40%; animation-delay: -10s; }

@keyframes float {
    0%   { transform: translate(0, 0) rotate(0deg) scale(1); }
    100% { transform: translate(100px, 50px) rotate(180deg) scale(1.2); }
}

.hero-wrap {
    display: grid;
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: 4rem;
    align-items: center;
    max-width: 1280px;
    width: 100%;
    z-index: 10;
}

.hero-text { text-align: left; }

.hero-art { position: relative; }
.hero-art img {
    width: 100%;
    height: auto;
    border-radius: 20px;
    box-shadow: 0 40px 80px -20px rgba(0,0,0,0.8),
                0 0 0 1px rgba(255,255,255,0.06);
}
.hero-art-caption {
    margin-top: 1rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-style: italic;
}

.venue-badge {
    display: inline-block;
    padding: 0.5rem 1.2rem;
    background: rgba(139, 92, 246, 0.15);
    border: 1px solid rgba(139, 92, 246, 0.3);
    color: #e2e8f0;
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 2rem;
    letter-spacing: 1.2px;
    text-transform: uppercase;
}

.title {
    font-size: clamp(2.2rem, 4vw, 3.75rem);
    margin-bottom: 2rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.authors { margin-bottom: 1rem; font-size: 1rem; line-height: 1.9; }
.author {
    color: #e2e8f0;
    text-decoration: none;
    margin-right: 0.75rem;
    display: inline-block;
    transition: color 0.2s;
}
.author:hover { color: var(--accent-blue); }
.author.principal { font-weight: 600; }

.affiliations {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 2rem;
}

.actions {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.btn {
    padding: 0.7rem 1.6rem;
    border-radius: 50px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-display);
    font-size: 0.95rem;
}

.btn-primary { background: var(--text-primary); color: var(--bg-dark); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 10px 25px -5px rgba(255,255,255,0.2); }
.btn-secondary { background: var(--glass-bg); color: var(--text-primary); border: 1px solid var(--glass-border); }
.btn-secondary:hover { background: rgba(255,255,255,0.1); transform: translateY(-2px); }

/* ---------- Puzzle ---------- */
.puzzle-section { padding: 5rem 0 3rem; }
.pull-quote {
    text-align: center;
    max-width: 900px;
    margin: 0 auto 4rem;
    padding: 0 1rem;
}
.pull-quote p {
    font-family: var(--font-display);
    font-size: clamp(1.4rem, 2.4vw, 2rem);
    font-weight: 400;
    line-height: 1.3;
    color: var(--text-primary);
    margin-bottom: 1rem;
    letter-spacing: -0.01em;
}
.pull-quote-attrib {
    color: var(--text-secondary);
    font-size: 0.9rem;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.puzzle-stats { max-width: 1000px; margin: 0 auto; }
.stat-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 14px;
    padding: 2rem 1.5rem;
    text-align: center;
}
.stat-value {
    font-family: var(--font-display);
    font-weight: 800;
    font-size: 3rem;
    background: linear-gradient(135deg, #60a5fa, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}
.stat-label { color: var(--text-secondary); font-size: 0.95rem; line-height: 1.4; }

/* ---------- Abstract ---------- */
.glass-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 3rem;
    font-size: 1.05rem;
    color: var(--text-tertiary);
    max-width: 900px;
    margin: 0 auto;
}
.abstract-card p { margin-bottom: 1.5rem; }
.abstract-card p:last-child { margin-bottom: 0; }
.abstract-card strong { color: #fff; font-weight: 600; }
.abstract-card em { color: #e2e8f0; }

/* ---------- Grids ---------- */
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 1.5rem; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1.5rem; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(360px, 1fr)); gap: 2rem; }

/* ---------- Moral cards ---------- */
.moral-card {
    background: linear-gradient(180deg, var(--glass-bg) 0%, rgba(0,0,0,0) 100%);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 2rem 1.75rem 4.5rem;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    min-height: 300px;
}
.moral-card:hover { transform: translateY(-6px); background: linear-gradient(180deg, rgba(255,255,255,0.05) 0%, var(--glass-bg) 100%); }

.card-ring {
    position: absolute;
    top: -60px; right: -60px;
    width: 160px; height: 160px;
    border-radius: 50%;
    opacity: 0.12;
    transition: opacity 0.3s, transform 0.3s;
}
.moral-card:hover .card-ring { opacity: 0.25; transform: scale(1.1); }
.ring-selfish    { background: radial-gradient(circle, var(--moral-selfish) 0%, transparent 70%); }
.ring-kin        { background: radial-gradient(circle, var(--moral-kin) 0%, transparent 70%); }
.ring-reciprocal { background: radial-gradient(circle, var(--moral-reciprocal) 0%, transparent 70%); }
.ring-universal  { background: radial-gradient(circle, var(--moral-universal) 0%, transparent 70%); }

.card-icon { font-size: 1.8rem; margin-bottom: 1.25rem; }
.type-selfish    .card-icon { color: var(--moral-selfish); }
.type-kin        .card-icon { color: var(--moral-kin); }
.type-reciprocal .card-icon { color: var(--moral-reciprocal); }
.type-universal  .card-icon { color: var(--moral-universal); }

.moral-card h3 { margin-bottom: 0.75rem; font-size: 1.2rem; }
.moral-card p { color: var(--text-secondary); font-size: 0.9rem; line-height: 1.55; }

.dominates {
    position: absolute;
    bottom: 1.25rem; left: 1.75rem; right: 1.75rem;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    color: #94a3b8;
    letter-spacing: 0.5px;
    padding-top: 0.75rem;
    border-top: 1px solid rgba(255,255,255,0.08);
}

/* ---------- Figure cards ---------- */
.figure-card {
    background: #fff;
    border-radius: 14px;
    overflow: hidden;
    border: 1px solid var(--glass-border);
    box-shadow: 0 20px 50px -20px rgba(0,0,0,0.7);
}
.figure-card img {
    width: 100%;
    height: auto;
    display: block;
    background: #fff;
}
.figure-card figcaption {
    padding: 1.25rem 1.5rem;
    font-size: 0.92rem;
    line-height: 1.5;
    color: #334155;
    background: #f8fafc;
    border-top: 1px solid #e2e8f0;
}
.figure-card figcaption strong { color: #0f172a; font-weight: 600; }
.figure-card figcaption em { color: #475569; }
.figure-card.wide { max-width: 1100px; margin: 0 auto 3rem; }

/* ---------- Framework info cards ---------- */
.framework-grid { margin-top: 3rem; }
.info-card {
    background: var(--bg-panel);
    border: 1px solid var(--glass-border);
    border-radius: 14px;
    padding: 2rem;
}
.info-card h3 {
    font-size: 1.15rem;
    margin-bottom: 1.25rem;
    color: #fff;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}
.info-card h3 i { color: var(--accent-blue); }
.info-card ul { list-style: none; padding: 0; }
.info-card li {
    position: relative;
    padding-left: 1.1rem;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.55;
}
.info-card li::before {
    content: '›';
    position: absolute;
    left: 0;
    color: var(--accent-purple);
    font-weight: 700;
}
.info-card strong { color: var(--text-primary); font-weight: 600; }

/* ---------- Validation grid ---------- */
.validation-grid { gap: 2rem; }

/* ---------- Results cards ---------- */
.results-grid { gap: 2rem; margin-top: 3rem; }
.result-card {
    background: var(--bg-panel);
    border: 1px solid var(--glass-border);
    border-radius: 14px;
    padding: 2rem;
    transition: transform 0.3s, border-color 0.3s;
}
.result-card:hover {
    transform: translateY(-4px);
    border-color: rgba(255,255,255,0.15);
}
.result-tag {
    display: inline-block;
    padding: 0.35rem 0.9rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    font-weight: 600;
    letter-spacing: 0.5px;
    margin-bottom: 1.25rem;
    text-transform: uppercase;
}
.tag-kin        { background: rgba(213, 94, 0, 0.18); color: #FCA77A; border: 1px solid rgba(213, 94, 0, 0.4); }
.tag-reciprocal { background: rgba(86, 180, 233, 0.18); color: #7CC9F0; border: 1px solid rgba(86, 180, 233, 0.4); }
.tag-universal  { background: rgba(0, 114, 178, 0.22); color: #60A5FA; border: 1px solid rgba(0, 114, 178, 0.5); }
.tag-opacity    { background: rgba(148, 163, 184, 0.18); color: #cbd5e1; border: 1px solid rgba(148, 163, 184, 0.35); }

.result-card h3 {
    font-size: 1.15rem;
    margin-bottom: 0.9rem;
    color: #fff;
    font-weight: 600;
    line-height: 1.35;
}
.result-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}
.result-card em { color: #e2e8f0; font-style: normal; font-weight: 500; }

/* ---------- Takeaways ---------- */
.takeaway-grid { gap: 1.5rem; margin-top: 2rem; }
.takeaway-card {
    background: linear-gradient(165deg, rgba(139, 92, 246, 0.08) 0%, var(--glass-bg) 60%);
    border: 1px solid var(--glass-border);
    border-radius: 14px;
    padding: 2rem;
    position: relative;
}
.takeaway-num {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent-purple);
    margin-bottom: 1rem;
    letter-spacing: 1px;
}
.takeaway-card h3 {
    font-size: 1.1rem;
    line-height: 1.4;
    margin-bottom: 0.85rem;
    color: #fff;
}
.takeaway-card p {
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.55;
}
.takeaway-card em { color: #e2e8f0; font-style: italic; }

/* ---------- Citation ---------- */
.code-block {
    background: #111116;
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    padding: 1.75rem;
    position: relative;
    overflow-x: auto;
    max-width: 900px;
    margin: 0 auto;
}
.code-block pre {
    font-family: var(--font-mono);
    color: #a78bfa;
    line-height: 1.6;
    font-size: 0.88rem;
}
.copy-btn {
    position: absolute;
    top: 0.9rem;
    right: 0.9rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: white;
    padding: 0.4rem 0.6rem;
    border-radius: 6px;
    cursor: pointer;
    transition: 0.2s;
}
.copy-btn:hover { background: rgba(255,255,255,0.1); }

.links-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    justify-content: center;
    margin-top: 2.5rem;
}
.link-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.55rem 1.1rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 50px;
    color: var(--text-primary);
    text-decoration: none;
    font-size: 0.88rem;
    font-weight: 500;
    transition: all 0.2s;
}
.link-pill:hover {
    background: rgba(255,255,255,0.08);
    border-color: rgba(255,255,255,0.2);
    transform: translateY(-2px);
}

/* ---------- Footer ---------- */
footer {
    text-align: center;
    padding: 3rem;
    color: var(--text-secondary);
    border-top: 1px solid var(--glass-border);
    margin-top: 4rem;
    font-size: 0.88rem;
}

/* ---------- Scroll animations ---------- */
.reveal { opacity: 0; transform: translateY(30px); transition: all 0.8s cubic-bezier(0.5, 0, 0, 1); }
.reveal.active { opacity: 1; transform: translateY(0); }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
    .hero-wrap { grid-template-columns: 1fr; gap: 2.5rem; }
    .hero-text { text-align: center; }
    .actions { justify-content: center; }
    .authors { font-size: 0.95rem; }
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
    .section { padding: 4rem 0; }
}

@media (max-width: 600px) {
    .container { padding: 0 1.25rem; }
    .glass-card { padding: 2rem 1.5rem; }
    .info-card, .result-card, .takeaway-card { padding: 1.5rem; }
    .code-block { padding: 1.25rem; font-size: 0.78rem; }
    .code-block pre { font-size: 0.78rem; }
}