:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #495057;
    --text-tertiary: #6c757d;
    --accent: #228B22;
    --accent-hover: #1a6b1a;
    --accent-light: #228B2215;
    --border: #dee2e6;
    --shadow: rgba(0, 0, 0, 0.08);
    --card-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    --nav-height: 60px;
}

[data-theme="dark"] {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --text-primary: #c9d1d9;
    --text-secondary: #8b949e;
    --text-tertiary: #6e7681;
    --accent: #32CD32;
    --accent-hover: #228B22;
    --accent-light: #32CD3215;
    --border: #30363d;
    --shadow: rgba(0, 0, 0, 0.3);
    --card-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

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

/* Navigation */
.navigation {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    backdrop-filter: blur(10px);
    background-color: rgba(var(--bg-primary), 0.8);
}

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

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    display: flex;
    align-items: center;
}

.home-icon {
    margin-right: 8px;
    display: inline-flex;
    align-items: center;
    text-decoration: none;
}

.home-icon .icon {
    width: 20px;
    height: 20px;
}

[data-theme="light"] .home-icon {
    color: #000;
}

[data-theme="dark"] .home-icon {
    color: #fff;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--accent);
}

/* Theme Toggle */
.theme-toggle {
    background: none;
    border: 2px solid var(--accent);
    color: var(--accent);
    padding: 0.4rem 0.8rem;
    border-radius: 2rem;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
    margin-left: 1rem;
}

.theme-toggle:hover {
    background-color: var(--accent);
    color: var(--bg-primary);
}

/* Hero Section */
.hero {
    margin-top: var(--nav-height);
    padding: 5rem 0;
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
}

.hero-content {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--accent);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.hero-location {
    color: var(--text-tertiary);
    margin-bottom: 2rem;
}

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

.hero-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.2rem;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    text-decoration: none;
    border-radius: 0.5rem;
    border: 2px solid var(--border);
    transition: all 0.3s ease;
    font-weight: 500;
}

.hero-link:hover {
    border-color: var(--accent);
    color: var(--accent);
    transform: translateY(-2px);
    box-shadow: var(--card-shadow);
}

.icon {
    width: 20px;
    height: 20px;
}

.hero-image {
    position: relative;
}

.hero-image img {
    width: 280px;
    height: 280px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--accent);
    box-shadow: 0 10px 30px var(--shadow);
}

/* Sections */
.about-section,
.experience-section,
.projects-section,
.skills-section {
    padding: 5rem 0;
}

.experience-section,
.skills-section {
    background-color: var(--bg-secondary);
}

.section-title {
    font-size: 2.5rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
    text-align: center;
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

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

/* Timeline */
.timeline {
    position: relative;
    padding: 2rem 0;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 30px;
    top: 0;
    bottom: 0;
    width: 2px;
    background-color: var(--border);
}

.timeline-item {
    position: relative;
    padding-left: 70px;
    padding-bottom: 3rem;
}

.timeline-marker {
    position: absolute;
    left: 22px;
    top: 0;
    width: 18px;
    height: 18px;
    background-color: var(--accent);
    border-radius: 50%;
    border: 3px solid var(--bg-secondary);
}

.timeline-content {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--card-shadow);
}

.company-info {
    margin-bottom: 1.5rem;
}

.company-name {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin-bottom: 0.3rem;
}

.company-location {
    color: var(--text-tertiary);
    font-size: 0.9rem;
}

.role-section {
    margin-bottom: 1.5rem;
}

.role-section:last-child {
    margin-bottom: 0;
}

.role-title {
    font-size: 1.2rem;
    color: var(--accent);
    margin-bottom: 0.3rem;
}

.role-period {
    color: var(--text-tertiary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.role-summary {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.see-more-btn {
    background: none;
    border: none;
    color: var(--accent);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    padding: 0.5rem 0;
    transition: color 0.3s ease;
    margin-top: 0.5rem;
}

.see-more-btn:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.achievements {
    list-style: none;
}

.achievements li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
}

.achievements li:before {
    content: "▸";
    position: absolute;
    left: 0;
    color: var(--accent);
}

/* Projects */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.project-card {
    background-color: var(--bg-secondary);
    border-radius: 0.5rem;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px var(--shadow);
}

.project-content {
    padding: 2rem;
}

.project-name {
    font-size: 1.3rem;
    color: var(--accent);
    margin-bottom: 0.5rem;
}

.project-meta {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    font-size: 0.9rem;
    color: var(--text-tertiary);
}

.project-description {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Skills */
.skills-intro {
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-secondary);
}

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

.skill-category {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--card-shadow);
}

.category-title {
    font-size: 1.3rem;
    color: var(--accent);
    margin-bottom: 1.5rem;
}

.skill-subcategory {
    margin-bottom: 1.5rem;
}

.subcategory-title {
    font-size: 1rem;
    color: var(--text-primary);
    margin-bottom: 0.8rem;
    font-weight: 600;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.skill-tag {
    background-color: var(--accent-light);
    color: var(--text-primary);
    padding: 0.4rem 1rem;
    border-radius: 2rem;
    font-size: 0.9rem;
    border: 1px solid var(--accent);
    transition: all 0.3s ease;
}

.skill-tag:hover {
    background-color: var(--accent);
    color: white;
}

/* Footer */
.footer {
    background-color: var(--bg-tertiary);
    padding: 3rem 0 2rem;
    margin-top: 5rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 2rem;
}

.footer-title {
    font-size: 1.2rem;
    color: var(--accent);
    margin-bottom: 1rem;
}

.institution,
.cert-provider {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.3rem;
}

.degree,
.cert-item {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    color: var(--text-tertiary);
}

/* Mobile Styles */
@media (max-width: 768px) {
    .nav-links {
        gap: 1rem;
    }
    
    .nav-link {
        display: none;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-image {
        order: -1;
    }
    
    .hero-image img {
        width: 200px;
        height: 200px;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-links {
        justify-content: center;
    }
    
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item {
        padding-left: 50px;
    }
    
    .timeline-marker {
        left: 12px;
    }
    
    .projects-grid,
    .skills-grid {
        grid-template-columns: 1fr;
    }
}

.mobile-only {
    display: none;
}

@media (max-width: 768px) {
    .mobile-only {
        display: inline-flex;
    }
}

.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    font-size: 1.2rem;
    color: var(--text-tertiary);
}

.error {
    text-align: center;
    padding: 2rem;
    color: #dc3545;
}