:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border-color: #e5e7eb;
    --accent-color: #3b82f6;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --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;
}

[data-theme="dark"] {
    --primary-color: #3b82f6;
    --primary-dark: #2563eb;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-tertiary: #374151;
    --border-color: #374151;
    --accent-color: #60a5fa;
}

* {
    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: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: var(--transition);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: var(--bg-primary);
    backdrop-filter: blur(10px);
    background-color: rgba(var(--bg-primary-rgb, 255, 255, 255), 0.9);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: var(--transition);
}

[data-theme="dark"] .navbar {
    background-color: rgba(17, 24, 39, 0.9);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

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

.nav-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

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

.btn-download {
    padding: 0.5rem 1rem;
    background-color: var(--primary-color);
    color: white !important;
    border-radius: 0.375rem;
    transition: var(--transition);
}

.btn-download:hover {
    background-color: var(--primary-dark);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    flex-direction: column;
    gap: 4px;
}

.nav-toggle span {
    width: 25px;
    height: 2px;
    background-color: var(--text-primary);
    transition: var(--transition);
}

.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
}

.sun-icon {
    display: block;
}

.moon-icon {
    display: none;
}

[data-theme="dark"] .sun-icon {
    display: none;
}

[data-theme="dark"] .moon-icon {
    display: block;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 20px 80px;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.hero-content {
    max-width: 800px;
    text-align: center;
}

.hero-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.accent {
    color: var(--primary-color);
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.8;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 0.375rem;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    display: inline-block;
}

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

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

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

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

/* Sections */
section {
    padding: 80px 0;
}

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

/* About Section */
.about {
    background-color: var(--bg-secondary);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.125rem;
    line-height: 1.8;
    color: var(--text-secondary);
}

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

/* Experience Timeline */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    padding-left: 60px;
    margin-bottom: 3rem;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: 11px;
    top: 0;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    border: 4px solid var(--bg-primary);
}

.timeline-date {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.timeline-content h3 {
    font-size: 1.25rem;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.timeline-content h4 {
    font-size: 1rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-weight: 500;
}

.timeline-content ul {
    list-style: none;
    color: var(--text-secondary);
}

.timeline-content li {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: 0.5rem;
}

.timeline-content li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--primary-color);
}

/* Projects */
.projects {
    background-color: var(--bg-secondary);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

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

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

.project-card h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.project-card p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tech-tag {
    padding: 0.25rem 0.75rem;
    background-color: var(--bg-tertiary);
    color: var(--primary-color);
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 500;
}

/* Skills */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.skill-category h3 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

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

.skill-tag {
    padding: 0.5rem 1rem;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border-radius: 0.375rem;
    font-size: 0.875rem;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

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

/* Contact */
.contact {
    background-color: var(--bg-secondary);
    text-align: center;
}

.contact-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    text-decoration: none;
    border-radius: 0.375rem;
    font-weight: 500;
    transition: var(--transition);
}

.contact-link:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

.contact-link svg {
    width: 20px;
    height: 20px;
}

/* Footer */
.footer {
    background-color: var(--bg-tertiary);
    padding: 2rem 0;
    text-align: center;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--bg-primary);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

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

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

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

    .timeline::before {
        left: 10px;
    }

    .timeline-item {
        padding-left: 40px;
    }

    .timeline-item::before {
        left: 1px;
    }
}