/* ================================================
   CSS Variables - Theme Configuration
   ================================================ */
:root {
    /* ── Hero background image ──────────────────────────────────────────────
       To swap the background, change this URL to any image path or data URI.
       e.g. --hero-bg-image: url('my-custom-bg.jpg');
       ──────────────────────────────────────────────────────────────────── */
    --hero-bg-image: url('hero-bg.svg');

    /* Dark Theme (Default) */
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --bg-card: #1c2128;
    
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --text-muted: #6e7681;
    
    --accent-primary: #58a6ff;
    --accent-secondary: #388bfd;
    --accent-glow: rgba(88, 166, 255, 0.15);
    
    --border-color: #30363d;
    --border-highlight: #484f58;
    
    --timeline-line: #30363d;
    --timeline-dot: #58a6ff;
    --timeline-dot-bg: #0d1117;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(88, 166, 255, 0.2);
    
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
    
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 20px;
}

/* Light Theme */
[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f6f8fa;
    --bg-tertiary: #eaeef2;
    --bg-card: #ffffff;
    
    --text-primary: #1f2328;
    --text-secondary: #656d76;
    --text-muted: #8c959f;
    
    --accent-primary: #0969da;
    --accent-secondary: #0550ae;
    --accent-glow: rgba(9, 105, 218, 0.1);
    
    --border-color: #d0d7de;
    --border-highlight: #8c959f;
    
    --timeline-line: #d0d7de;
    --timeline-dot: #0969da;
    --timeline-dot-bg: #ffffff;
    
    --shadow-sm: 0 1px 2px rgba(31, 35, 40, 0.08);
    --shadow-md: 0 4px 12px rgba(31, 35, 40, 0.12);
    --shadow-lg: 0 8px 24px rgba(31, 35, 40, 0.16);
    --shadow-glow: 0 0 20px rgba(9, 105, 218, 0.15);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-normal), color var(--transition-normal);
    overflow-x: hidden;
}

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

a:hover {
    color: var(--accent-secondary);
}

ul {
    list-style: none;
}

/* ================================================
   Navigation
   ================================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(13, 17, 23, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    transition: background var(--transition-normal), border-color var(--transition-normal);
}

[data-theme="light"] .navbar {
    background: rgba(255, 255, 255, 0.85);
}


.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--accent-primary);
    letter-spacing: -1px;
}

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

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

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-primary);
    transition: width var(--transition-normal);
}

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

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

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

/* Nav Actions */
.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

/* Theme Toggle */
.theme-toggle {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-glow);
}

.theme-toggle svg {
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

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

.icon-sun {
    display: none;
}

.icon-moon {
    display: block;
}

[data-theme="light"] .icon-sun {
    display: block;
}

[data-theme="light"] .icon-moon {
    display: none;
}

/* Hamburger Button */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.5rem 0.6rem;
    cursor: pointer;
    transition: border-color var(--transition-fast);
    width: 40px;
    height: 40px;
}

.hamburger span {
    display: block;
    width: 18px;
    height: 2px;
    background: var(--text-secondary);
    border-radius: 2px;
    transition: transform var(--transition-normal), opacity var(--transition-fast), background var(--transition-fast);
    transform-origin: center;
}

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

.hamburger:hover span {
    background: var(--accent-primary);
}

.hamburger.open span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.hamburger.open span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0);
}

.hamburger.open span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Mobile Nav Drawer */
.mobile-nav {
    display: none;
    position: fixed;
    top: 65px;
    left: 0;
    right: 0;
    z-index: 999;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    transform: translateY(-100%);
    opacity: 0;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
    pointer-events: none;
}

.mobile-nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
}

.mobile-nav ul {
    padding: 1rem 2rem;
    display: flex;
    flex-direction: column;
    gap: 0;
}

.mobile-nav ul li a {
    display: block;
    padding: 0.85rem 0;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 1rem;
    border-bottom: 1px solid var(--border-color);
    transition: color var(--transition-fast);
}

.mobile-nav ul li:last-child a {
    border-bottom: none;
}

.mobile-nav ul li a:hover {
    color: var(--accent-primary);
}

/* Mobile Navigation */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hamburger,
    .mobile-nav {
        display: flex;
    }
}

/* ================================================
   Hero Section
   ================================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 6rem 2rem 4rem;
    position: relative;
    overflow: hidden;
}

/* Background image — absolutely fills the hero behind all content.
   To change the background: update the <img src="..."> in index.html */
.hero-bg-img {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    z-index: 0;
    pointer-events: none;
    user-select: none;
}

/* Light theme: tone down the dark-blue SVG on white */
[data-theme="light"] .hero-bg-img {
    opacity: 0.35;
}

/* Vignette + accent glows sit above the background image but below content */
.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    z-index: 1;
    background:
        radial-gradient(ellipse at center, transparent 35%, var(--bg-primary) 80%),
        radial-gradient(ellipse at 20% 20%, var(--accent-glow) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, var(--accent-glow) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 700px;
    animation: fadeInUp 0.8s ease forwards;
}

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

.hero-name {
    font-size: clamp(2.5rem, 8vw, 4.5rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-primary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-title {
    font-family: var(--font-mono);
    font-size: clamp(1rem, 3vw, 1.25rem);
    color: var(--accent-primary);
    margin-bottom: 1rem;
    font-weight: 500;
}

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

.hero-cta {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.6rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 1px solid transparent;
    text-decoration: none;
}

.btn-primary {
    background: var(--accent-primary);
    color: #fff;
    border-color: var(--accent-primary);
}

.btn-primary:hover {
    background: var(--accent-secondary);
    border-color: var(--accent-secondary);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

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

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

.hero-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.hero-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    transition: all var(--transition-normal);
}

.hero-link:hover {
    color: var(--accent-primary);
    border-color: var(--accent-primary);
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

/* ================================================
   Sections
   ================================================ */
.section {
    padding: 6rem 2rem;
    position: relative;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
}

.section-title {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 3rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 60px;
    height: 3px;
    background: var(--accent-primary);
    border-radius: 2px;
}

/* ================================================
   About Section
   ================================================ */
.about-content {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    position: relative;
    transition: all var(--transition-normal);
}

.about-content:hover {
    border-color: var(--border-highlight);
    box-shadow: var(--shadow-md);
}

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

/* ================================================
   Experience Timeline
   ================================================ */
.timeline {
    position: relative;
    padding-left: 30px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 6px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--timeline-line);
}

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

.timeline-marker {
    position: absolute;
    left: -30px;
    top: 6px;
    width: 14px;
    height: 14px;
    background: var(--timeline-dot-bg);
    border: 2px solid var(--timeline-dot);
    border-radius: 50%;
    transition: all var(--transition-fast);
}

.timeline-item:hover .timeline-marker {
    transform: scale(1.3);
    box-shadow: 0 0 12px var(--accent-primary);
}

.timeline-content {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    transition: all var(--transition-normal);
}

.timeline-content:hover {
    border-color: var(--border-highlight);
    box-shadow: var(--shadow-md);
}

.timeline-period {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--accent-primary);
    font-weight: 500;
}

.timeline-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 0.5rem 0 0.25rem;
    color: var(--text-primary);
}

.timeline-company {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.timeline-description {
    padding-left: 1.25rem;
}

.timeline-description li {
    position: relative;
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

.timeline-description li::before {
    content: '▹';
    position: absolute;
    left: -1.25rem;
    color: var(--accent-primary);
}

/* ================================================
   Skills Section
   ================================================ */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.skill-category {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    transition: all var(--transition-normal);
}

.skill-category:hover {
    border-color: var(--border-highlight);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

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

.skill-tag {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    padding: 0.4rem 0.8rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

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

/* ================================================
   Certifications Section
   ================================================ */
.certifications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.certification-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    text-align: center;
    transition: all var(--transition-normal);
}

.certification-card:hover {
    border-color: var(--border-highlight);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.certification-icon {
    font-size: 2rem;
    display: block;
    margin-bottom: 1rem;
}

.certification-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.certification-issuer {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* ================================================
   Education Section
   ================================================ */
.education-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.education-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
    transition: all var(--transition-normal);
}

.education-item:hover {
    border-color: var(--border-highlight);
    box-shadow: var(--shadow-md);
}

.education-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.education-degree {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.education-institution {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.education-year {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--accent-primary);
}

/* ================================================
   Contact Section
   ================================================ */
.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.contact-text {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-weight: 500;
    transition: all var(--transition-normal);
}

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

.contact-link svg {
    flex-shrink: 0;
}

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

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

/* ================================================
   Scroll-to-Top Button
   ================================================ */
.scroll-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 900;
    width: 44px;
    height: 44px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transform: translateY(10px);
    pointer-events: none;
    transition: all var(--transition-normal);
}

.scroll-top.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.scroll-top:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
    box-shadow: var(--shadow-glow);
}

/* ================================================
   Scroll Animations
   ================================================ */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ================================================
   Responsive Adjustments
   ================================================ */
@media (max-width: 768px) {
    .section {
        padding: 4rem 1.5rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .timeline {
        padding-left: 20px;
    }
    
    .timeline::before {
        left: 4px;
    }
    
    .timeline-marker {
        left: -20px;
        width: 10px;
        height: 10px;
    }
    
    .skills-grid,
    .certifications-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-links {
        flex-direction: column;
        align-items: center;
    }
    
    .contact-link {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }

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

    .btn {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }

    .scroll-top {
        bottom: 1.25rem;
        right: 1.25rem;
    }
}

/* ================================================
   Reduced Motion
   ================================================ */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }

    .fade-in {
        opacity: 1;
        transform: none;
    }

    html {
        scroll-behavior: auto;
    }
}

/* ================================================
   Print Styles
   ================================================ */
@media print {
    .navbar,
    .theme-toggle,
    .hero-links {
        display: none;
    }
    
    .hero {
        min-height: auto;
        padding: 2rem;
    }
    
    .section {
        padding: 2rem 1rem;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .timeline-content,
    .skill-category,
    .certification-card,
    .education-item,
    .about-content {
        box-shadow: none;
        border-color: #ccc;
    }
}