:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #64748b;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --border-color: #e2e8f0;
    --accent-color: #3b82f6;
    --warning-color: #f59e0b;
    --success-color: #10b981;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.7;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    font-size: 16px;
}

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

/* Hero Section */
.hero {
    padding: 8rem 0 6rem;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #f8fafc;
    text-align: center;
}

.hero-authors a {
    color: #f8fafc;
}

.hero-authors a:hover {
    color: #e2e8f0;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 3rem;
    opacity: 0.95;
    font-weight: 300;
}

.hero-authors {
    margin: 3rem 0;
}

.author-group h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
}

.authors-list {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 1rem;
}

.author {
    font-size: 1.1rem;
    font-weight: 500;
}

.author sup {
    font-size: 0.8em;
    margin-left: 2px;
}

.affiliations {
    margin: 1rem 0;
    font-size: 0.95rem;
    opacity: 0.9;
}

.affiliations p {
    margin: 0.25rem 0;
}

.corresponding {
    margin-top: 1rem;
    font-size: 0.9rem;
    opacity: 0.85;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 3rem;
}

.btn {
    padding: 0.875rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    display: inline-block;
    border: 2px solid transparent;
}

.btn-primary {
    background: transparent;
    color: white;
    border-color: white;
}

.btn-primary:hover {
    background: white;
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: transparent;
    color: white;
    border-color: white;
}

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

/* Sections */
.section {
    padding: 5rem 0;
}

.section:nth-child(even) {
    background-color: var(--bg-secondary);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 2.5rem;
    color: var(--text-primary);
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 1rem;
}

.content {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-secondary);
}

.content p {
    margin-bottom: 1.5rem;
}

.content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 2rem 0 1rem;
    color: var(--text-primary);
}

.content ul {
    margin-left: 2rem;
    margin-bottom: 1.5rem;
}

.content li {
    margin-bottom: 0.75rem;
}

/* Abstract */
.abstract-content {
    background: var(--bg-tertiary);
    padding: 2rem;
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
    font-size: 1.1rem;
    line-height: 1.8;
}

.abstract-content p {
    margin-bottom: 1rem;
}

/* Definition Box */
.definition-box {
    background: linear-gradient(135deg, #667eea15 0%, #764ba215 100%);
    border: 2px solid var(--primary-color);
    border-radius: 12px;
    padding: 2rem;
    margin: 2rem 0;
}

.definition-box h3 {
    color: var(--primary-color);
    margin-top: 0;
    margin-bottom: 1rem;
}

.property-list,
.mechanism-list {
    list-style: none;
    margin-left: 0;
}

.property-list li,
.mechanism-list li {
    background: var(--bg-secondary);
    padding: 1.5rem;
    margin-bottom: 1rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.property-list li strong,
.mechanism-list li strong {
    color: var(--primary-color);
    display: block;
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

/* Levels Container */
.levels-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.level-card {
    background: white;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.level-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.level-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.level-number {
    background: var(--primary-color);
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
}

.level-card h3 {
    margin: 0;
    font-size: 1.3rem;
    color: var(--text-primary);
}

.level-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-style: italic;
}

.level-features {
    list-style: none;
    margin-left: 0;
}

.level-features li {
    margin-bottom: 0.75rem;
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.level-features strong {
    color: var(--text-primary);
}

/* Workflow Steps */
.workflow-steps {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin: 2rem 0;
}

.workflow-step {
    display: flex;
    gap: 2rem;
    align-items: flex-start;
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    border-left: 4px solid var(--primary-color);
}

.step-number {
    background: var(--primary-color);
    color: white;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.step-content h3 {
    margin-top: 0;
    margin-bottom: 0.75rem;
    color: var(--primary-color);
}

.step-content p {
    margin-bottom: 0;
}

/* Challenge List */
.challenge-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin: 2rem 0;
}

.challenge-item {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    border-left: 4px solid var(--warning-color);
    box-shadow: var(--shadow-sm);
}

.challenge-item h3 {
    color: var(--warning-color);
    margin-top: 0;
    margin-bottom: 1rem;
}

/* Implication Sections */
.implication-section {
    margin: 2rem 0;
    padding: 2rem;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.implication-section h3 {
    color: var(--primary-color);
    margin-top: 0;
}

/* Highlight Boxes */
.highlight-box {
    background: linear-gradient(135deg, #667eea15 0%, #764ba215 100%);
    border-left: 4px solid var(--primary-color);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 2rem 0;
    font-size: 1.1rem;
}

.central-claim-box {
    background: #ecfdf5;
    border-left: 4px solid var(--success-color);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 2rem 0;
    font-size: 1.1rem;
}

.central-claim-box strong {
    color: var(--text-primary);
}

.summary-box {
    background: var(--bg-tertiary);
    border-left: 4px solid var(--secondary-color);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 2rem 0;
    font-style: italic;
}

.warning-box {
    background: #fef3c7;
    border-left: 4px solid var(--warning-color);
    padding: 1.5rem;
    border-radius: 8px;
    margin: 1rem 0;
}

/* Citation Section */
.citation-section {
    padding: 3rem 0;
}

.citation-note {
    margin-bottom: 1.5rem;
    font-size: 1.05rem;
}

.citation-code {
    background: #f6f8fa;
    color: #111827;
    border-radius: 8px;
    padding: 1.5rem 1.75rem;
    font-family: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
    font-size: 0.85rem;
    line-height: 1.6;
    overflow-x: auto;
    border: 1px solid #d0d7de;
    box-shadow: var(--shadow-sm);
}

.citation-code pre {
    margin: 0;
}

/* Figure Container */
.figure-container {
    margin: 2rem 0;
}

.figure-box {
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
}

.figure-label {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.figure-image {
    margin: 1.5rem 0;
    border-radius: 8px;
    overflow: hidden;
    background: white;
    box-shadow: var(--shadow-md);
    display: flex;
    justify-content: center;
    align-items: center;
}

.figure-img {
    max-width: 100%;
    height: auto;
    display: block;
    border-radius: 8px;
}

.figure-caption {
    color: var(--text-secondary);
    font-style: italic;
    line-height: 1.6;
    margin-top: 1rem;
    text-align: left;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0;
    text-align: center;
}

.footer p {
    margin: 0.5rem 0;
    opacity: 0.8;
}

.footer-note {
    font-size: 0.9rem;
    opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .container {
        padding: 0 1rem;
    }

    .levels-container {
        grid-template-columns: 1fr;
    }

    .workflow-step {
        flex-direction: column;
    }

    .authors-list {
        flex-direction: column;
        gap: 0.75rem;
    }

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

    .btn {
        width: 100%;
        max-width: 300px;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 6rem 0 4rem;
    }

    .hero-title {
        font-size: 2rem;
    }

    .section {
        padding: 3rem 0;
    }
}