/* ========================================
   CSS Reset & Base Styles
   ======================================== */

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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --bg-white: #ffffff;
    --bg-gray: #f8fafc;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-white);
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

img {
    max-width: 100%;
    height: auto;
}

/* ========================================
   Container & Layout
   ======================================== */

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

.section {
    padding: 5rem 0;
}

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

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    text-align: center;
    color: var(--text-primary);
}

/* ========================================
   Navigation Bar
   ======================================== */

.navbar {
    position: sticky;
    top: 0;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

.nav-menu a:hover {
    color: var(--primary-color);
}

.nav-menu a:hover::after {
    width: 100%;
}

/* ========================================
   Hero Section
   ======================================== */

.hero {
    padding: 6rem 0;
    background: linear-gradient(135deg, #f8fafc 0%, #e0e7ff 100%);
}

.hero-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.chinese-name {
    font-size: 2rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.hero-interests {
    background-color: var(--bg-white);
    padding: 1.5rem;
    border-radius: 12px;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
}

.hero-interests h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.hero-interests p {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.8;
}

.hero-bio {
    background-color: rgba(255, 255, 255, 0.85);
    padding: 1.25rem 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    border-left: 3px solid var(--primary-color);
}

.hero-bio p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.7;
    margin: 0;
}

.hero-contact-quick {
    background-color: rgba(255, 255, 255, 0.7);
    padding: 1rem 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.hero-contact-quick p {
    margin: 0.5rem 0;
    color: var(--text-secondary);
}

.hero-contact-quick strong {
    color: var(--text-primary);
    margin-right: 0.5rem;
}

.hero-contact-quick a {
    color: var(--primary-color);
    text-decoration: none;
}

.hero-contact-quick a:hover {
    text-decoration: underline;
}

.hero-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 500;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

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

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

.btn-secondary {
    background-color: white;
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.profile-placeholder {
    text-align: center;
    position: relative;
}

.placeholder-text {
    margin-top: 1rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-style: italic;
}

/* ========================================
   Education Section
   ======================================== */

.education-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
    max-width: 1000px;
    margin: 0 auto;
}

.education-card {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border-left: 4px solid var(--primary-color);
}

.education-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-5px);
}

.edu-period {
    display: inline-block;
    padding: 0.375rem 0.875rem;
    background-color: #dbeafe;
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.education-card h3 {
    font-size: 1.375rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.edu-major {
    font-size: 1.05rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.edu-institution {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
}

.edu-gpa {
    color: var(--text-primary);
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
}

.edu-research {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border-color);
}

.edu-advisor {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-top: 0.5rem;
}

.edu-research strong,
.edu-advisor strong {
    color: var(--text-primary);
}

/* ========================================
   Publications Section
   ======================================== */

.publications-summary {
    text-align: center;
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    padding: 1rem;
    background-color: var(--bg-gray);
    border-radius: 8px;
}

.publication-list {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

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

.publication-item:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-5px);
}

.pub-badge {
    display: inline-block;
    padding: 0.375rem 0.875rem;
    background: linear-gradient(135deg, #2563eb 0%, #7c3aed 100%);
    color: white;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.pub-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.pub-authors {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.pub-authors strong {
    color: var(--primary-color);
}

.pub-venue {
    color: var(--text-secondary);
    font-style: italic;
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.pub-description {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ========================================
   Projects Section
   ======================================== */

.project-list {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.project-item {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.project-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.project-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.project-header h3 {
    font-size: 1.375rem;
    font-weight: 600;
    color: var(--text-primary);
    flex: 1;
}

.project-period {
    padding: 0.375rem 0.875rem;
    background-color: #dbeafe;
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    white-space: nowrap;
}

.project-role,
.project-description,
.project-contribution,
.project-award {
    margin-bottom: 1rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.project-role strong,
.project-contribution strong,
.project-award strong {
    color: var(--text-primary);
}

.project-award {
    padding: 1rem;
    background-color: #fef3c7;
    border-left: 3px solid #f59e0b;
    border-radius: 6px;
    margin-bottom: 0;
}

/* ========================================
   Skills Section
   ======================================== */

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

.skill-category {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.skill-category:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-5px);
}

.skill-category h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--primary-color);
}

.skill-category ul {
    list-style: none;
    padding: 0;
}

.skill-category li {
    padding: 0.625rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
}

.skill-category li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* ========================================
   Contact Section
   ======================================== */

.contact-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    max-width: 900px;
    margin: 0 auto;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.contact-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.contact-item svg {
    flex-shrink: 0;
    color: var(--primary-color);
    margin-top: 0.25rem;
}

.contact-item h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.contact-item p {
    color: var(--text-secondary);
}

.contact-item a {
    color: var(--primary-color);
    text-decoration: underline;
}

.contact-item a:hover {
    color: var(--primary-hover);
}

/* ========================================
   Footer
   ======================================== */

.footer {
    background-color: var(--text-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

.footer p {
    margin: 0.25rem 0;
    opacity: 0.8;
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 768px) {
    .container {
        padding: 0 1.5rem;
    }

    .section {
        padding: 3rem 0;
    }

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

    .nav-menu {
        gap: 1rem;
        font-size: 0.875rem;
    }

    .hero {
        padding: 4rem 0;
    }

    .hero-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }

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

    .chinese-name {
        font-size: 1.5rem;
    }

    .hero-links {
        justify-content: center;
    }

    .hero-image {
        order: -1;
    }

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

    .project-header {
        flex-direction: column;
    }

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

    .contact-info {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }

    .btn {
        padding: 0.625rem 1.25rem;
        font-size: 0.875rem;
    }

    .pub-title {
        font-size: 1.125rem;
    }

    .project-header h3 {
        font-size: 1.125rem;
    }
}

/* ========================================
   Print Styles
   ======================================== */

@media print {
    .navbar,
    .footer {
        display: none;
    }

    .section {
        page-break-inside: avoid;
    }

    .publication-item,
    .project-item {
        page-break-inside: avoid;
    }
}