/* ===========================
   Reset & Base Styles
   =========================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Colors */
    --primary-color: #2563eb;
    --secondary-color: #7c3aed;
    --accent-color: #06b6d4;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-dark: #111827;
    --border-color: #e5e7eb;
    --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);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-base: 16px;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Layout */
    --container-max-width: 1200px;
    --nav-height: 70px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

html {
    scroll-behavior: smooth;
    font-size: var(--font-size-base);
}

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

/* ===========================
   Typography
   =========================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

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

/* ===========================
   Container & Layout
   =========================== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ===========================
   Navigation
   =========================== */
.nav-container {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    height: var(--nav-height);
}

.nav-content {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    transition: color var(--transition-base);
}

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

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
}

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

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width var(--transition-base);
}

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

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

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

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

/* ===========================
   Hero Section
   =========================== */
.hero {
    padding: calc(var(--nav-height) + var(--spacing-3xl)) 0 var(--spacing-3xl);
    background: linear-gradient(135deg, #f9fafb 0%, #ffffff 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(37, 99, 235, 0.05) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-content {
    max-width: 800px;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 4rem;
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color), var(--accent-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.7;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

/* ===========================
   Buttons
   =========================== */
.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: all var(--transition-base);
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background: #1d4ed8;
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

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

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

/* ===========================
   Section Styles
   =========================== */
section {
    padding: var(--spacing-3xl) 0;
}

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

.section-subtitle {
    text-align: center;
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

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

.about-content {
    display: grid;
    gap: var(--spacing-xl);
}

.about-text {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.expertise-list {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.expertise-list li {
    padding: var(--spacing-md);
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition-base);
}

.expertise-list li:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.stat-card {
    text-align: center;
    padding: var(--spacing-lg);
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: 1rem;
    color: var(--text-secondary);
}

/* ===========================
   Experience Section
   =========================== */
.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;
    padding-bottom: var(--spacing-xl);
}

.timeline-marker {
    position: absolute;
    left: 11px;
    top: 0;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    border: 4px solid var(--bg-primary);
    z-index: 1;
}

.timeline-content {
    background: white;
    padding: var(--spacing-lg);
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
}

.timeline-content:hover {
    box-shadow: var(--shadow-lg);
}

.timeline-header h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-xs);
}

.company {
    display: block;
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.period {
    display: block;
    color: var(--text-light);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
}

.timeline-body {
    display: grid;
    gap: var(--spacing-md);
}

.achievement {
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: 8px;
    border-left: 3px solid var(--primary-color);
}

.achievement h4 {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.achievement p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin: 0;
}

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

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

.project-card {
    background: white;
    padding: var(--spacing-lg);
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transition: transform var(--transition-base);
}

.project-card:hover::before {
    transform: scaleX(1);
}

.project-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-4px);
}

.project-tag {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary-color);
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: var(--spacing-md);
}

.project-card h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
}

.project-card p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-md);
}

.project-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition-base);
}

.project-link:hover {
    color: var(--secondary-color);
}

/* ===========================
   Blog Section
   =========================== */
.blog-list {
    max-width: 900px;
    margin: 0 auto;
}

.blog-item {
    background: white;
    padding: var(--spacing-lg);
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-lg);
    transition: var(--transition-base);
    border-left: 4px solid var(--primary-color);
}

.blog-item:hover {
    box-shadow: var(--shadow-lg);
    transform: translateX(4px);
}

.blog-featured-item {
    border-left-width: 6px;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.02) 0%, rgba(255, 255, 255, 1) 100%);
}

.blog-date {
    color: var(--text-light);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
}

.blog-item h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.blog-featured-item h3 {
    font-size: 1.75rem;
}

.blog-item p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-md);
    font-size: 1.05rem;
}

.blog-tags {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    margin-bottom: var(--spacing-md);
}

.tag {
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
}

.read-more-link {
    display: inline-block;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition-base);
    margin-top: var(--spacing-sm);
}

.read-more-link:hover {
    color: var(--secondary-color);
    gap: var(--spacing-sm);
}

.blog-featured {
    background: var(--bg-secondary);
}

/* ===========================
   Contact Section
   =========================== */
.contact {
    background: var(--bg-secondary);
}

.contact-content {
    max-width: 800px;
    margin: 0 auto;
}

.contact-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.contact-card {
    background: white;
    padding: var(--spacing-xl);
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    text-decoration: none;
    color: var(--text-primary);
    transition: var(--transition-base);
}

.contact-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-4px);
}

.contact-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.contact-card h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
}

.contact-card p {
    color: var(--text-secondary);
    margin: 0;
}

/* ===========================
   Footer
   =========================== */
.footer {
    background: var(--bg-dark);
    color: white;
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.footer p {
    margin-bottom: var(--spacing-xs);
}

.footer-subtitle {
    color: var(--text-light);
    font-size: 0.875rem;
}

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-links {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: var(--spacing-lg);
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }
    
    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    h2 {
        font-size: 2rem;
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .btn {
        text-align: center;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .expertise-list {
        grid-template-columns: 1fr;
    }
    
    .timeline::before {
        left: 10px;
    }
    
    .timeline-marker {
        left: 1px;
    }
    
    .timeline-item {
        padding-left: 40px;
    }
}

@media (max-width: 480px) {
    :root {
        --font-size-base: 14px;
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
}

/* ===========================
   Animations
   =========================== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

/* Smooth scroll offset for fixed nav */
section {
    scroll-margin-top: var(--nav-height);
}