/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --color-bg: #fafafa;
    --color-surface: #ffffff;
    --color-text: #1a1a1a;
    --color-text-muted: #666666;
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-border: #e5e5e5;
    --color-accent: #f0f4ff;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --container-width: 1100px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 5rem;
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --transition: 150ms ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Typography */
h1, h2, h3, h4 {
    font-weight: 600;
    line-height: 1.3;
}

h1 { font-size: 3rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.25rem; }

p {
    margin-bottom: var(--spacing-sm);
}

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

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

/* Navigation */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 100;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-md);
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text);
}

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

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
}

.nav-links a {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color var(--transition);
}

.nav-links a:hover {
    color: var(--color-text);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
    border: none;
    text-align: center;
}

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

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

.btn-secondary {
    background: transparent;
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    border-color: var(--color-text);
    color: var(--color-text);
}

/* Hero */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xxl) var(--spacing-md);
    text-align: center;
    background: linear-gradient(180deg, var(--color-accent) 0%, var(--color-bg) 100%);
}

.hero-content {
    max-width: 700px;
}

.hero h1 {
    margin-bottom: var(--spacing-xs);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-md);
}

.hero-description {
    font-size: 1.1rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-lg);
}

.hero-cta {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    flex-wrap: wrap;
}

/* Sections */
.section {
    padding: var(--spacing-xxl) 0;
}

.section-title {
    margin-bottom: var(--spacing-xl);
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 50px;
    height: 3px;
    background: var(--color-primary);
    margin: var(--spacing-sm) auto 0;
    border-radius: 2px;
}

/* About */
.about {
    background: var(--color-surface);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: start;
}

.about-text p {
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-md);
}

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

.about-skills h3 {
    margin-bottom: var(--spacing-md);
}

.skills-grid {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.skill-tag {
    display: inline-block;
    padding: 0.4rem 0.8rem;
    background: var(--color-accent);
    color: var(--color-primary);
    font-size: 0.85rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
}

/* Projects */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.project-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: box-shadow var(--transition), transform var(--transition);
}

.project-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.project-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xs);
}

.project-header h3 {
    margin: 0;
}

.project-status {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    color: #16a34a;
    background: #dcfce7;
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
}

.project-date {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

.project-role {
    font-size: 0.9rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.project-description {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-md);
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.project-tags span {
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
    background: var(--color-bg);
    color: var(--color-text-muted);
    border-radius: var(--radius-sm);
}

/* Contact */
.contact {
    background: var(--color-surface);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: var(--spacing-xl);
    align-items: start;
}

.contact-info p {
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-lg);
}

.social-links {
    display: flex;
    gap: var(--spacing-sm);
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: var(--radius-md);
    background: var(--color-bg);
    color: var(--color-text-muted);
    transition: all var(--transition);
}

.social-link:hover {
    background: var(--color-primary);
    color: white;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    padding: 0.75rem 1rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 1rem;
    transition: border-color var(--transition), box-shadow var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* Footer */
.footer {
    padding: var(--spacing-lg) 0;
    text-align: center;
    border-top: 1px solid var(--color-border);
}

.footer p {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    margin: 0;
}

/* Responsive */
@media (max-width: 768px) {
    h1 { font-size: 2.25rem; }
    h2 { font-size: 1.75rem; }
    
    .nav-links {
        gap: var(--spacing-md);
    }
    
    .about-content,
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .hero {
        padding-top: calc(var(--spacing-xxl) + 60px);
    }
}

@media (max-width: 480px) {
    h1 { font-size: 1.875rem; }
    
    .nav-links {
        gap: var(--spacing-sm);
    }
    
    .nav-links a {
        font-size: 0.8rem;
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .hero-cta .btn {
        width: 100%;
    }
}