/* ============================================
   The Stackelberg Speaker - GitHub Pages Style
   ============================================ */

:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #e0e7ff;
    --accent: #8b5cf6;
    --accent-pink: #ec4899;
    --accent-cyan: #06b6d4;
    --bg: #ffffff;
    --bg-alt: #f8fafc;
    --text: #1e293b;
    --text-secondary: #64748b;
    --border: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.08);
    --shadow-glow: 0 0 30px rgba(99, 102, 241, 0.15);
    --radius: 16px;
    --radius-sm: 10px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    color: var(--text);
    line-height: 1.7;
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
    padding-top: 0;
}

/* ---- Starry Sky Canvas ---- */
#starry-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    background: linear-gradient(180deg, #0a0a1a 0%, #0d1127 40%, #111827 100%);
    pointer-events: none;
}

/* ---- Navigation Bar ---- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 0.8rem 0;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    background: transparent;
}

.navbar.nav-scrolled {
    background: rgba(10, 10, 26, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(99, 102, 241, 0.1);
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.15);
    padding: 0.5rem 0;
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-size: 0.95rem;
    font-weight: 700;
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    letter-spacing: -0.01em;
    transition: color 0.3s ease;
}

.nav-logo:hover {
    color: #c7d2fe;
}

.nav-links {
    display: flex;
    gap: 0.3rem;
}

.nav-link {
    color: rgba(255, 255, 255, 0.6);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 500;
    padding: 0.4rem 0.85rem;
    border-radius: 8px;
    transition: all 0.3s ease;
    position: relative;
}

.nav-link:hover {
    color: rgba(255, 255, 255, 0.95);
    background: rgba(255, 255, 255, 0.06);
}

.nav-link.active {
    color: #c7d2fe;
    background: rgba(99, 102, 241, 0.15);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ---- Scroll Reveal Animation ---- */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1),
                transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* ---- Hero ---- */
.hero {
    position: relative;
    padding: 9rem 0 5rem;
    text-align: center;
    overflow: hidden;
    background: transparent;
    color: #fff;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 20% 40%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 75% 60%, rgba(139, 92, 246, 0.12) 0%, transparent 45%),
        radial-gradient(ellipse at 50% 80%, rgba(236, 72, 153, 0.06) 0%, transparent 40%);
    pointer-events: none;
}

/* 动态网格背景 */
.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(99, 102, 241, 0.06) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99, 102, 241, 0.06) 1px, transparent 1px);
    background-size: 60px 60px;
    mask-image: radial-gradient(ellipse at center, black 30%, transparent 70%);
    -webkit-mask-image: radial-gradient(ellipse at center, black 30%, transparent 70%);
    pointer-events: none;
    animation: gridPulse 8s ease-in-out infinite;
}

@keyframes gridPulse {
    0%, 100% { opacity: 0.4; }
    50% { opacity: 0.8; }
}

/* 浮动光球 */
.hero-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(60px);
    pointer-events: none;
    animation: orbFloat 12s ease-in-out infinite;
}

.hero-orb-1 {
    width: 300px;
    height: 300px;
    background: rgba(99, 102, 241, 0.15);
    top: -80px;
    left: -50px;
    animation-delay: 0s;
}

.hero-orb-2 {
    width: 250px;
    height: 250px;
    background: rgba(139, 92, 246, 0.12);
    bottom: -60px;
    right: -30px;
    animation-delay: -4s;
}

.hero-orb-3 {
    width: 180px;
    height: 180px;
    background: rgba(236, 72, 153, 0.1);
    top: 40%;
    left: 60%;
    animation-delay: -8s;
}

@keyframes orbFloat {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(30px, -20px) scale(1.05); }
    66% { transform: translate(-20px, 15px) scale(0.95); }
}

.hero .container {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 2.1rem;
    font-weight: 800;
    line-height: 1.25;
    margin-bottom: 1.5rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    background: linear-gradient(135deg, #e0e7ff 0%, #a5b4fc 25%, #c4b5fd 50%, #93c5fd 75%, #e0e7ff 100%);
    background-size: 200% 200%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: titleShimmer 6s ease-in-out infinite;
}

@keyframes titleShimmer {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.hero-authors {
    font-size: 1.05rem;
    color: #cbd5e1;
    margin-bottom: 0.6rem;
    font-weight: 400;
    letter-spacing: 0.02em;
}

.hero-affiliation {
    font-size: 0.92rem;
    color: rgba(167, 139, 250, 0.7);
    margin-bottom: 2.5rem;
    font-weight: 400;
    font-style: italic;
    letter-spacing: 0.01em;
}

.hero-links {
    display: flex;
    gap: 0.85rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    cursor: pointer;
    position: relative;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
    color: #fff;
    border: none;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.35);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.06);
    color: #e2e8f0;
    border: 1px solid rgba(255, 255, 255, 0.12);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.12);
    border-color: rgba(255, 255, 255, 0.25);
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(255, 255, 255, 0.08);
}

/* ---- Sections ---- */
.section {
    padding: 5rem 0;
    position: relative;
    background: var(--bg);
}

.section-alt {
    background: var(--bg-alt);
}

/* 给 section-alt 加微妙的顶部渐变分隔 */
.section-alt::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--border), transparent);
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2.5rem;
    color: var(--text);
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    margin: 0.75rem auto 0;
    border-radius: 2px;
}

.subsection-title {
    font-size: 1.35rem;
    font-weight: 600;
    margin: 3rem 0 1rem;
    color: var(--text);
}

.subsection-title:first-of-type {
    margin-top: 0;
}

/* ---- Abstract ---- */
.abstract-text {
    max-width: 850px;
    margin: 0 auto;
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.85;
    position: relative;
    padding: 2rem 2.5rem;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.03) 0%, rgba(139, 92, 246, 0.03) 100%);
    border-radius: var(--radius);
    border: 1px solid rgba(99, 102, 241, 0.08);
}

/* 装饰性引号 */
.abstract-text::before {
    content: '\201C';
    position: absolute;
    top: -0.2rem;
    left: 1rem;
    font-size: 4rem;
    font-family: Georgia, serif;
    color: var(--primary);
    opacity: 0.15;
    line-height: 1;
}

.abstract-text p + p {
    margin-top: 1rem;
}

.abstract-text strong {
    color: var(--text);
    font-weight: 600;
}

/* ---- Motivation Layout ---- */
.motivation-layout {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 3rem;
    align-items: center;
    max-width: 900px;
    margin: 0 auto;
}

.motivation-img {
    max-width: 380px;
}

.motivation-img img {
    width: 100%;
    height: auto;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.motivation-img:hover img {
    transform: scale(1.02);
}

.motivation-text h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text);
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.motivation-text p {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 0.75rem;
}

.motivation-text strong {
    color: var(--primary-dark);
    font-weight: 600;
}

/* ---- Figures ---- */
.figure-container {
    text-align: center;
    margin: 2rem 0;
}

.figure-img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1),
                box-shadow 0.4s ease;
}

.figure-img:hover {
    transform: scale(1.01);
    box-shadow: 0 15px 50px rgba(0, 0, 0, 0.12);
}

.figure-caption {
    margin-top: 1rem;
    font-size: 0.92rem;
    color: var(--text-secondary);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.6;
}

.figure-caption strong {
    color: var(--text);
}

/* ---- Method Steps ---- */
.method-intro {
    max-width: 850px;
    margin: 0 auto 2.5rem;
    font-size: 1.05rem;
    color: var(--text-secondary);
    text-align: center;
    line-height: 1.85;
}

.method-intro strong {
    color: var(--text);
}

.method-steps {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin-top: 3rem;
}

.step-card {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem 1.5rem;
    text-align: center;
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1),
                box-shadow 0.3s ease;
    position: relative;
    overflow: hidden;
}

/* 卡片顶部渐变装饰线 */
.step-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    opacity: 0;
    transition: opacity 0.3s ease;
}

.step-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 40px rgba(99, 102, 241, 0.1);
}

.step-card:hover::before {
    opacity: 1;
}

.step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: #fff;
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 1.2rem;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.step-card h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.step-card p {
    font-size: 0.92rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ---- Game Grid ---- */
.game-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.game-card {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem 1.5rem;
    text-align: center;
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1),
                box-shadow 0.3s ease;
    position: relative;
    overflow: hidden;
}

/* 每张游戏卡片不同颜色的顶部装饰 */
.game-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    transition: height 0.3s ease;
}

.game-card:nth-child(1)::before { background: linear-gradient(90deg, #ef4444, #f97316); }
.game-card:nth-child(2)::before { background: linear-gradient(90deg, #6366f1, #8b5cf6); }
.game-card:nth-child(3)::before { background: linear-gradient(90deg, #06b6d4, #3b82f6); }
.game-card:nth-child(4)::before { background: linear-gradient(90deg, #10b981, #06b6d4); }

.game-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.08);
}

.game-card:hover::before {
    height: 4px;
}

.game-icon {
    font-size: 2.8rem;
    margin-bottom: 1rem;
    display: inline-block;
    transition: transform 0.3s ease;
}

.game-card:hover .game-icon {
    transform: scale(1.15);
}

.game-card h3 {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.game-card p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.55;
    margin-bottom: 1rem;
}

.game-tag {
    display: inline-block;
    padding: 0.25rem 0.85rem;
    border-radius: 999px;
    background: var(--primary-light);
    color: var(--primary);
    font-size: 0.78rem;
    font-weight: 600;
    transition: all 0.3s ease;
}

.game-card:hover .game-tag {
    background: var(--primary);
    color: #fff;
}

/* ---- Citation ---- */
.citation-block {
    position: relative;
    background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    border-radius: var(--radius);
    padding: 1.5rem 2rem;
    max-width: 750px;
    margin: 0 auto;
    overflow: hidden;
    border: 1px solid rgba(99, 102, 241, 0.15);
    box-shadow: 0 0 30px rgba(99, 102, 241, 0.08);
}

/* 装饰性角落光效 */
.citation-block::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.08) 0%, transparent 60%);
    pointer-events: none;
}

.citation-block pre {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: #e2e8f0;
    line-height: 1.7;
    overflow-x: auto;
    white-space: pre;
    margin: 0;
    position: relative;
    z-index: 1;
}

.copy-btn {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.12);
    color: #94a3b8;
    padding: 0.4rem 0.6rem;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.3s ease;
    z-index: 2;
}

.copy-btn:hover {
    background: rgba(99, 102, 241, 0.2);
    border-color: rgba(99, 102, 241, 0.4);
    color: #c7d2fe;
}

/* ---- Footer ---- */
.footer {
    padding: 2.5rem 0;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    border-top: 1px solid var(--border);
    background: var(--bg-alt);
    position: relative;
    z-index: 1;
}

/* ---- Responsive ---- */
@media (max-width: 900px) {
    .hero-title {
        font-size: 1.6rem;
    }

    .nav-logo {
        display: none;
    }

    .nav-links {
        gap: 0.1rem;
    }

    .nav-link {
        font-size: 0.78rem;
        padding: 0.35rem 0.6rem;
    }

    .motivation-layout {
        grid-template-columns: 1fr;
    }

    .motivation-img {
        max-width: 320px;
        margin: 0 auto;
    }

    .method-steps {
        grid-template-columns: 1fr;
    }

    .game-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .analysis-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 600px) {
    .hero {
        padding: 7rem 0 3rem;
    }

    .hero-title {
        font-size: 1.3rem;
    }

    .section {
        padding: 3rem 0;
    }

    .section-title {
        font-size: 1.6rem;
    }

    .game-grid {
        grid-template-columns: 1fr;
    }

    .hero-links {
        flex-direction: column;
        align-items: center;
    }

    .container {
        padding: 0 1rem;
    }

    .abstract-text {
        padding: 1.5rem;
    }
}